-AD A135 812 CHARACTERIZATION OF AEROBIC CHEMICAL PROCESSES IN l/t

RESERVOIRS: PROBLEM DES..(U) ARMY ENGINEER WATERWAYSEXPERIMENT STATION VICKSBURG MS ENVIR..

UNCLASSIFIED R L CHEN ET AL OCT' 83 WES/TR/E-83-16 F/G 13/2 NL

E EEIEIIEESMhMhhEEMhEMhEINmEEMhhEEMhhEIEEMhhhMhMhEEEIMhEEMhMhMhEEEEIIIIIIIIIIIIIIT

IIIIIIIIII

.1 .4 '

MICR C I ? 'OI 1LI I ION ItI I t HAlO

44

I.

SECURITY CLASSIFICATION OF THIS PAGE ( PhA D _td)

REPOT DCUMNTATON AGEREAD INSTRUCTIONSREP TD EIO PO PLETIG FOR

1. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER

'I'chntcal Report E-83- I6 0__ _ __ _ _ _

4. TITLE (Arld Subtitl) S TYPE OF REPORT 8 PERIOD COVERED

CHARACIERI ZA'IION OF AEROBIC CIIEM 1CAL PROCESSES F ita I reportIN RESERVOIRS: PROBLEM I)ESCRIPrIION AND MODEIFORMULAT I ON - PERFORMING ORG, REPORT NUMBER

7. AUTHOR(.) 6. CONTRACT OR GRANT NUMBER(.)

Rex I. Chen, I)ouglas Gunnison, and

Jamlt' S a.non

9. PERFORMING ORGANIZATION NAME AND ADDRESS tO. PROGRAM ELEMENT. PROJECT, TASK

U. S. Army Enginteer Waterways Experiment Station AREAO WORK UNIT NUMBERS

Env i roinmt'altd 1 Laboratory EWQO Work nit 31594

P. 0. Box b3l], Vicksburg, Miss. 39180 ( IB. 2)

I. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE

Otice, Chief of Engineers, U. S. Army October 1983

Washington, D. C 20314 I3 NUMBER OF PAGES• 87'

14. MONITORING AGENCY NAME & ADDRESS(II dlff.or(t from Co.rtoaling Office) IS. SECURITY C. ASS. (.1 this report)

Uncl issi ledIS.. DECLASSIFICATION DOWNGRADING

SCHEDULE

16. DISTRIBUTION STATEMENT (of this1 Report)

Approved for pub I"i u rte I ea se; d i st r i bution nil I] inn t i ed.

17. DISTRIBUTION STATEMENT (of the b.trI.ct .nt.,.d In Block 20, If dilffsort fro. Repot)

It. SUPPLEMENTARY NOTES

Ava i I abl I t f rom Nat ioil. Techi cal In to ri t ion Servic e, 5285f Port Royal R0.If,Springt ield, Va. 22161.r I. KEY WORDS (Conin. on reov.e* .l. It nece..say nd idenify by block n.br)

At, rat io Reservoir st it icat foi1tChemica IS Reservoirs

Dissolved oxygen Water qualitvMathemat ical model's

20. A2STUACT (CC.Emf am .r1r s ft ffn y ad Ido. tify6). b lock ,o).lDest rat i ficat ion ot hypol imnet i " waters produces circulat ion that moves

dissolved oxygen Into tilt, Illoxic hypolimn ion of reservoirs. I)estratiti cationticreastes thei dissolved oxygen content of ,lnox ic .ltter and111 results in de-

creased concenltratiOls of the dissolved forms of i roii, manganese, immonitm,phosphorus, ,nod hydrogen sultidev. Aeration also aftfects water pli and tempera-tulre aidi reidox potential, which change tilt- t ransorll mation ratt" of variOuS

chemicals in reservoir ecosystems. A thorough review of existing lit eratur(Cont i nued)

s,,,- W3 n 1 ti or o ao ss OmLE~t Unclassified

SECUITY CLASSIFICATION OF THIS PAGE (Uh. Do. Ente. ted

-_ . . .. ., . ... . . . -:1

Unclassif ied

SECURITY CLASSIFICATION OF THIS PAGE(Vhl Date Btnmd)

20. ABSTRACT (Continued)

indicates that the factors affecting oxidation of nutrients and metals arehighly site specific. This report discusses oxidation pathways of chemicalsand important environmental parameters that affect the transformation rate ofselected nutrients and metals in fakes and reservoirs and presents a model forpredicting the transition from anaerobic to aerobic condition.

In order to better demonstrate the necessary components for an aerobicpredictive model, consideration was given to the basic concepts of the mostcommonly available equilibrium models for predicting water quality in lakes.Evaluation of the practicality of available models revealed that, althoughequilibrium models provide the flexible and comprehensive approaches necessaryfor water quality prediction, rate models are more precise and reliable intheir depiction of the transition from anoxic to aerobic conditions inreservoi rs.

Oxidation rates of selected nutrients and metals in U. S. Army Corps ofEngineers reservoirs were determined in environmentally controlled laboratoryinvestigations; field measurements of the fate of reduced iron and manganese inthe anoxic bottom water of Eau Galle Reservoir, Wisconsin, during destratifica-tion corroborated the laboratory results. These oxidation rate coefficientswill form the basic input variables for RE-AERS, a reaeration subroutine ofthe water quality evaluation model CE-QUAL-R1.

lA3t

"o @

Unclassified

SECURITY CLASSIFICATION Or THIS PAGEI(Wlh e n

Data Enterd)

PREFACE

This study was sponsored by the Office, Chief of Engineers (OCE),

U. S. Army, as a part of the Environmental Water Quality and Operational

Studies (EWQOS) Work Unit 31594 (IB.2) entitled Develop and Verify

Descriptions for Reservoir Chemical Processes. The OCE Technical Moni-

tors for EWQOS were Mr. Earl Eiker, Mr. John Bushman, and Mr. James L.

Gottesman.

The work was conducted during the period September 1978-June 1981

by the Environmental Laboratory, U. S. Army Engineer Waterways Experi-

ment Station (WES), Vicksburg, Mississippi, under the direction of

Dr. J. Harrison, Chief of the Environmental Laboratory (EL), and under

the general supervision of Mr. D. L. Robey, Chief of the Ecosystem

Research and Simulation Division (ERSD), and Dr. R. M. Engler, Chief

of the Ecological Effects and Regulatory Criteria Group. Program

Manager of EWQOS was Dr. J. L. Mahloch, EL. Some of the foundation work

for this study was performed as part of a U. S. Army Corps of Engineers

In-House Laboratory Independent Research Program (ILIR) Work Unit 111 06

entitled Mechanisms That Regulate the Degree of Oxidation-Reduction in

Anaerobic Sediments and Natural Water Systems.

This study was conducted by Drs. R. L. Chen and D. Gunnison and

Mr. J. M. Brannon, ERSD. Messrs. I. Smith, Jr., and T. C. Sturgis,

ERSD, assisted with the laboratory experimentation. This report was

written by Drs. Chen and Gunnison and Mr. Brannon and was reviewed

by Drs. R. H. Kennedy, Engler, and M. Zimmerman, ERSD.

Director of WES during this study and the preparation and publica-

tion of this report was COL Tilford C. Creel, CE. Technical Director

was Mr. F. R. Brown.

This report should be cited as follows:

Chen, R. L., Gunnison, D., and Brannon, J. M. 1983."Characterization of Aerobic Chemical Processes inReservoirs: Problem Description and Model Formulation,"Technical Report E-83-16, U. S. Army Engineer WaterwaysExperiment Station, Vicksburg, Miss.

I

CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I

LIST OF TABLES.............................3

LIST OF FIGURES.................................3

PART I: INTRODUCTION..........................5

Background................................5Purpose..............................7

PART 11: AEROBIC CHEMICAL TRANSFORMATIONS IN REAERATEJOR DESTRATIFIED RESERVOIR ECOSYSTEMS ............ 8

Literature Review.........................8Equilibrium Models Depicting Aerobic Processes. ......... 32

PART III: RE-AERS--REAERATION SUBROUTINF. ................ 37

Model Organization and Function..................37Interrelationships Among Reduced Chemicals as

the Anoxic Water Column Is Aerated ................ 41

PART IV: EVALUATION OF RELEVANT RATE DATA ................ 54

PART V: LABORATORY AND FIELD) STUDIES.................................

Materials and Methods.........................55Results..............................59

PART VI: SUMMARY AND CONCLUSIONS.....................70

REFERENCES................................71

TABLES 1-9

2

LI ST OF TABLES

No. Pa ~eI Smiumary of Previous Results on Oxygenrat ion K inet ics of

Ferrouls It-i o..........................80

2 Ox idat ion and T1ransftorma tion of Var iouls Reduced ConirPOnreni ttin Aerated Reservoi rs and Other FreshwaterEnv Iroriment s.........................5 1

3 Sumina IIry of M et hods U~sed to Obt aini Data .............. 82

4 Characteristics of Selected Sediment s and Sorils L;sedI fithe Laboratory Studies................... . .. .. .. .. ....

5 Changes i 1i Colcent ra t ins o f DO 111 the OverlIy inrg WterDuir inrg Aeiat ion Study.................. . . .. .. .. .. ....-

b Coricerit ratE in of NH, -N and No ,-N Iin Wa~itecrs iver l Iy ig Sedfr-mer, it s I romi Selectelt CE Rese, )vxo r r Svs t em Inriuha t ejUnder Aerobic Conidit ions at 20'L: p'gN/iri ..............

7 [hel( Rate of N Transftorimat ioris inr CE Rese rvoirr Svs (Lems

Inc-ubated Under Aerobic Conudit ionis at 200C fo'r 3 Iweek.ti the Dark.............................'

8 Changes of Inrorgani ic Phrosphiat e (01rt ho-P) Coricenit i.1t i r iii

t he Overly inrg Waters of SelIec ted CE Rese rvoi r Sy:stviemstinder Aerobic Conidit ion 15 rt 25CIII thle Libon.it u v

() Concerit rajt in o f Reduced Fe arid Mn I rI %a t 0ers iver I I r igSed irmen t s f roni SelIectLed CE Rese rvo i I- Sy -.t emis I if ribr t eltirde r- Ae rob ic Loud( i t I oils a t )00C , pg/iJ ............ S

LI1ST of'FIGRE

I 'I'hlermir I ly strat it jod reservoir arid ISSOCIrated _orrfi t[0orisoft low di ssolIved oxygen....................I

2 Al ternat ives for ai I- or oxygen inject ion ii hydropowerprojects.................... .. . . ... . .. .. .. . ......

-1 Outli no of pat hways of ca rbrori ii aqua tic or i rotimrerits . .. I

4 Out I I neo of pathways of init rogern ii aqua ti c envi ronmrent s i s

5 I ntercharige between water arid sodimienit P) coiartrnrts .. 20

6 OutlIi ne of pat hways of i ron andi manganese iii aqua ti cetiv i ronment s................................. .. . . .. . .. . . . ........

7 Redox potent ial-pil diagram indicatinig the staurIlity f ieldof common i ronr compounds................. ..

8 Cha nge s i ri 0') a nd s o I rib)I l n -onlcerit rait Iois w it Ii t Iirieini thle over Iy inrg wa t ers i ii a s tra t i ted CE~ re se rvoi I . 2-

LIST OF FIGURES

No Page

9 Thermal stratification cycle ................ 38

10 After hypolimnetic aeration: thermal stratificationCont inues in the reservoir; hypol imnion 1)0 level ismaintained at approximately 5-6 mg/I ............. 39

11 Mtajor chemical changes and pathways associated withanae rob ic cond it ions in thet hypol i inn ionl............42

12 Major chemical1 changes and pathways associatedI with thedest rat ificat ion perio(d in anoxi c hypo I imnn i onl........49

13 Sediment-water reactor for studying aerob ic conidit ionsin reservoirs..........................o

14 Changes in organic and i no rgan ic carbon cont ent s of thetoverlying water in Beech Fork Reservoir under aerobi c

and ainae robijc condi t ions......................................10115 Changes in organic and inorgan ic carbon contents of tire

overlying water in Browns Lake under aerobic andanaerobic cond it ions................. . . ... . .. .. .. .... I

16 Changes in organic and i no rgan ic ca rlon contents o1 tileoverlying water in Browns Lake (small co lumin) uideraerobic and anaerobic cond it ions .. ...........

17 Changes in organic and inorganic carbon contents of tilb,

overlying water in Fagle Lake under aerobic andanaerobic condi tions.................... 2

18 Changes iii organic and i no rga ni c carbon corntents o I threoverliy inrg water in Eau Gal Ic Rese rvo ir unide r ae rob ikcand anaerobic cond it ions ..................... 3

19 Changes in organic and i no rgaiic carbon contents of theoverlying water in Eaui Gal le Reservoir (smnall column)uinder aerobic and anaerobic condit i ons ............... 3

20 Changes in organ ic and i no rgan ic ca rbon conrtent s of tilieoverlying water in Richard B. Russell Reservoir mnderaerobic and anaerobic cond it ions .. .... .......

21 Map of Earn Gal le Reservoir, Wisconsin ........... o

4

CHARACTERIZATION OF AEROBIC CHEMICAL PROCESSES IN RESERVOIRS:

PROBLEM DESCRIPTION AND MODEL FORMULATION

PART 1: INTRODUCTION

Background

1. Many Corps of Engineers (CE) reservoirs have within the hypo-

limnion low concentrations of dissolved oxygen and high concentrations

of products of anaerobic transformation; consequently, these concentra-

tions occur in waters released from projects having bottom withdrawal.

Adverse impacts of low dissolved oxygen in reservoirs and their releases

have included harmful effects on aquatic biota, such as fish kills; loss

of project benefits from excessive growth of aquatic vegetation and

algae; increased operation and maintenance costs, especially as a result

of corrosion; and increased costs to downstream water users due to in-

creased requirements for water treatment.

2. Adding oxygen to an anoxic hypolimnion, either through

natural or mechanical destratification, will rapidly alleviate many

water quality problems caused by reduced chemical substances. Improve-

ment in water quality during the change from anaerobic to aerobic condi-

tions is a consequence of the oxidation of metals and nutrients, which

produces speciation and solubility changes that benefit water quality.

In some CE reservoirs suffering from severe anaerobic conditions,

mechanical aeration may be an acceptable means of alleviating the

associated water quality problems.

3. Artificial mixing and/or destratification of the anoxic hypo-

limnion to improve water quality has been attempted in a number of

stratified waterbodies. Several researchers have studied the effect of

aeration on nutrient availability in reservoir water (Bernhardt 1967;

Cooley et al. 1980; Strecker et al. 1977). Results indicate that in-

creasing the dissolved oxygen content of the anoxic water results in

decreases in the concentrations of manganese, iron, ammonia, hydrogen

sulfide, and phosphorus. The transformation rates of iron, manganese,

and phosphorus in reservoir waters are dependent upon the effects of

pH and oxidation state. High concentrations of organic matter in suir-

face waters also affect soluble iron levels due to the formation of

organic complexes.

4. Several attempts have been made to quantify oxidation rates

of reduced species found in water. However, with the exception of redox

potential, the effects of various environmental factors on the trans-

formation rates of iron, manganese, phosphorus, sulfur, and nitrogen

have not been well established. Effects of mixing, redox potential,

temperature, sediment type, and other environmental parameters on trans-

formation rates of nutrients and other contaminants must be known prior

to evaluation of any theoretical model.

5. Existing modeling approaches do not adequately predict the

many chemical ramifications of aerobic processes that occur in res-

ervoirs, although several models of pertinent individual processes do

exist. Moreover, present techniques give an ineffective characteriza-

tion of the sources and extent of reaeration, the development of aerobic

conditions in a previously anaerobic hypolimnion, the mobilization and

immobilization of nutrients and contaminants, and the rates at which

these processes occur. Managers lack the capability to evaluate various

alternative methods for encouraging or reducing these processes or to

determine the amount of reaeration required for improvement of impound-

ment water quality.

6. Field and laboratory investigations of chemical processes

associated with low oxygen concentration and anoxic conditions in res-

ervoirs have been conducted by the Environmental Laboratory, Waterways

Experiment Station (WES). Results of these studies have been compiled

and used to formulate a description of anaerobic conditions (Gunnison

and Brannon 1981). The present report offers a description of the

transition from anaerobic to aerobic conditions in reservoirs anid

proposes the chemical equilibrium model GEOCHEM and a reaction rate

model, RE-AERS, as basic models which function according to this de-

scription. The models will he incorporated into the WdES one-dimensional

6

reservoir water quality model CE-QUAL-RI (Environmental Laboratory 1982)

as a part of the Environmental and Water Quality Operational Studies

(EWQOS) Task IB.2.

Purpose

7. The objectives of this study were: (I) to compile and

organize existing information on aerobic processes occurring in lakes

and reservoirs; (2) to identify important aerobic chemical processes,

particularly those dealing with oxidation of reduced chemical species

that were accumulated during periods of anaerobic conditions and also

those that were important in shifting chemical species from th -

solved to the particulate phase; (3) to incorporate these proct into

a unified format of aerobic subroutine; and (4) to provide repr nta-

tive rate data for the various processes, as obtained in labor.

and field studies. The proposed aerobic model is intended for in

conjunction with the previously developed anaerobic subroutine (Gunnison

and Brannon 1981) to deal with water quality problems in reservoirs.

7

PART I I -AF:RoHB iCHEMICAL IRANSFORMAT Io(NS I N HFAFRATFI) ORI)ESTRATI FLEl) hESERVoIR ECOSYSTEMS

I.i tera t ure Review

D)i ssolIved oxy'gern and thle oxidat ion-

reduc ti on syst-en ini rese rvoirs -s

8. Oxygenl SOo iility is di rcCtlIy proport ionalI to tit he art ia I

presstire of oxygen in the gas phase and decreases iii a nonlinear Iianne r

as temperat ure icreases . TrO date, most measurement s ofI the ox idat ion-

reduct ion st atus of the water-s;ed imerit system have invwolIved redox po-

tent ial1, Ehi or E 7 (Eli corrected to pH 7) The theoretical Eli of water

cont a iing dissolved oxygen call he expressed as:

Eli =F -R' I~l ()

whe re

FE s t narr~ rd ox i da t i oil po ten[it i a I voL a ge

F a radayv cons taniit iii hlea t on it s

R = t hie gas cons tant

T=tihre absolu te temrperature

a OHI= t ire act i viy o 0f hyivdrox I i oir.s

p), tlire pajrt ial 1p)ressrr re o t oxygen

At I atiri, I 8'C , EqratL i oil ( m uav ht. rewr itterr as:

Eir 1. 234 - 0. 05b p11 + 0.0145 log p0,, (2)

Wi th thIis eqruat iorr, a redox potenrtialI of ahourt 800 111V call het calIculiat ed

for oxygen-satuirated niaturalI surf-ace water. i,.serverl potent ialIs inr

oxygenated lake water are usuially lower, approxinratelv 400 to 600 mV',

(Huntchinson 1957) . In accordance with Equrat ion (2) , thre rediox poten-

tijal of an aerated water system is relatively insensi tive to oxygen conl-

cent rat ion . Only a 30-nrV decrease in Ei w,-,, ohse rved when thre oxygen

8

concent rat ionl decreased f rom 100 to 0. 1 percent saturat ion in water.

Thus, a shi ft from oxidizing to reducing conditions will not occur until

the oxygen supply has been nearly exhausted (Greenwood 1962). The verti-

cal distribution of Eb in lake waters has been monitored numerous times,

with typical values of lake water surfaces ranging from 420 to 520 mV

(Hutchinson 1957). In hypolimnetic waters of meromictic lakes, Eh can

decline to approximately 80 mV. Much lower Ehi values are expected

within the sediments (i.e. -150 mV and lower). Under oxidative condi-

tions, the Eh of the oxidized layer appearing at the water-sediment

interface is about 100 mV or higher. Similar Eli distribution patterns

have also been recorded in flooded soil systems such as rice paddy

fields. Below the oxidized microzone, sediment Eli is invariably from

0 to about -200 mV, similar to the values recorded for flooded soils

(Chen et al. 1979; Bell 1969; Turner and Patrick 1968). Flooded

soils tend to reach a fairly stable pH in the range of 6.7 to 7.2

(Ponnamperuma et al. 1966). The pH of acid soil high in iron is con-

trolled by the Fe2 (Off) 8 -H20-CO2 system, while the p1l of calcareous soils

is defined by the partial pressure of CO2 in the CaCO 3-H 20-CO2 system.

Thermal stratification

9. Many CE reservoirs develop thermal stratification, resulting

in density differences between water layers (Figure 1), which isolates

the hypolimnion. This isolation, coupled with strong oxygen demand,

usually produces a low dissolved oxygen concentration in hypolimnetic

waters. Associated with the development of low dissolved oxygen con-

centration is the release from the sediments into the water of products

of anaerobic processes, including reduced forms of iron, manganese,

reduced organic compounds, nitrogen, and hydrogen sulfide. Many of

these products adversely affect the quality of water destined for human

consumption, recreation, and fishery uses. The hypolimnetic oxygen

deficit in most lakes and reservoirs is usually due to the biological

and chemical decomposition of organic matter; the clinograde oxygen

distribution curve shown in Figure I commonly occurs in productive

lakes during summer stratification. Under such conditions,

9

ATMOSPHERICREAERA TION

- - • WARM ISOTHERMICEPILIMNION 0 ABUNDANT OXYGEN

WARMWATER FISHERY

WA'M TO COLD THERMAL DISCONTINUITYj L METALIMNION 0 VA. k3LE OXYGEN

0 M!' D FISHERY

0 COLD ISOTHERMIC0 OXYGEN LOW OR ABSENT INCREASED

£ HYPOLIMNION CONCENTRATIONS OF SOLUBLE FORMSSI OF CONTAMINANTS AND NUTRIENTS

-jLCOLDWATER FISHERY IF OXYGEN ADEQUATEd. , ,-. ..

"'" . 'SEDIMENT REGION OF MATERIALADSORPTION AND RELEASE

TYPICAL VERTICAL TEMPERATURE AND DODISTRIBUTIONS DURING STRATIFICATION Z TEMPERATURE

, EPILIMNION

METALIMNION

- _ HYPOLIMNION

BOTTOM

Figure 1. Thermally stratified reservoir and associatedconditions of low dissolved oxygen (DO)

reaeration of anoxic hypolimnetic waters is minimal until destratifi-

cation occurs.

10. Biogeochemical transformations of nutrients and metals tinder

anaerobic conditions differ greatly from transformations in aerobic en-

vironments. Microbial and biochemical reactions in anaerobic environ-

ments commonly generate high concentrations of soluble forms of iron,

manganese, ammonium, phosphorus, and sulfide that can yield undesirable

tastes and odors or even toxic conditions. Release of nutrients from

sediments to overlying water may also support undesirable algal blooms,

although significant amounts of phosphorus may also be released in many

types of lake sediments under aerobic conditions (Hoidren and Armstrong

1980; Lee 1970).

11. Mechanical aeration methods have been used to improve water

10

quality and dt ssolved oxygen levels in anoxic hypolimnia of some strati-

tied reservoir proj -ts. figure 2 illustrates one type of mechanical

aerator along with several other methods for aerating reservoir releases.

Large-scale mechanical aeration has beet, ill service in CE reservoirs at

Allatoona Lake and Clark Hill Lake for many years. Alternating aerobic

and anaerobic conditions, however, by periodically introducing air into

anoxic hypolimnetic waters, may reduce costs and mainrtain acceptable

water quality. The success of periodic aeration will primarily depend

on the kinetics of oxidation and reduction reactions that occur in the

reservoir hypolimnion.

SWA TER SURFACE ,1AI HS

EPILIMNION

METALIMNIONDA LINE IN

suppoR r Bgo v; F ILL L INE

11WNJECTION

HYPOLIMNION ar r ine

12 Te uren lc o " knwldg abu u |in rn omtin

DRAIN L INE INJECTION-

""

D- RAFT T(.]Bf

INJECTION

Figure 2. Alternatives for air or oxygen injectionin hydropower projects

12. The current lack of knowledge about nutrient transformations

under alternating aerobic-anaerobic conditions and of nutrient flux in

water makes it impossible to predict precisely the nutrient, manganese,

iron, and sulfide levels in reservoir water at a given time. Available

technical information does not appear to be sufficient to forecast water

quality in newly flooded or established CE reservoirs under reaerated or

naturally destratified conditions. Therefore, most current mechanical

11

destrat if icat ion approaches do not operate at maxi mum e f iciency because

the reservoi r manager does not know when procedures should he ini t iated

or terminated.

Types and sources ofnutrients in CE reservoirs

13. Major aquatic plant nutrients in reservoirs, as in other nat-

ural water systems, are inorganic carbon, orthophosphate, nitrate, and

ammonium. Organic forms of phosphorus and nitrogen may also be assimi-

lated by organisms or converted to inorganic forms by biological or

chemical reactions. Although carbon is essential for growth of aquatic

plants, evideuce to date indicates that carbon (in the form oi CO 2 ) be-

comes limiting only under highly eutrophic conditions. Other essential

nutrients for growth of aquatic plants include iron, sulfur, potassium,

magnesiun, calcium, boron, zinc, copper, molybdenum, manganese , cobalt,

sodium, and chlorine. It is generally agreed, however, that nitrogen

and phosphorus are the key elements in controlling the growth of aquatic

plants in most freshwater ecosystems.

14. Nutrient sources include runoff from rural areas, agricul-

tural drainage, atmospheric precipitation, urban runoff, nutrient re-

lease from reservoir sediments, and eutrophic inflow waters and sediment

from upstream. Because of the nature and location ol most CE reservoirs,

the major source of nutrients entering the water is often runoff from

cultivated agricultural lands. Excessive nutrients can also originate

from poorly managed forest lands and mines. Nutrient-enriched runoff

from feedlots anti from cattle grazing near the reservoir are other

important sources. Furthermore, reservoir sediment often contains high

concentrations of nutrients which may be released to the overlying water

through anaerobic nutrient cycles, even when external nutrient loadings

are reduced. Consequently, for any given reservoir, all poten ttial

sources must be studied to predict the degree of eutrophication.

15. Problems with excessive nutrient loading and high dissolved

oxygen demands in reservoirs frequently are most intensive during the

first few years of impoundment. New reservoirs are not only subjected

to external (allochthonous) loadings, but also contain a significant

12

internal (autochthonous) loading and oxygen demand resulting from the

decomposition of inundated herbaceous plants, litter, leaves, and organ-

ically rich topsoil. In contrast, decomposition of woody plant material,

such as trees, probably is not a significant cause of eutrophication and

high dissolved oxygen demand because this material degrades slowly. Ef-

fective preimpoundment management and site preparation policies cannot

be formulated until sufficient information is obtained on the relative

importance of various materials as sinks for dissolved oxygen and sources

of nutrients.

lb. Most nutrients entering CE reservoirs are from nonpoint

sources which cannot be controlled by the CE; however, the CE can limit

internal nutrient regeneration through project design and operation

(Keeley et al. 1978). Generally, any procedure that maintains dissolved

oxygen concentrations of at least 2.0 mg! 2 in a reservoir hypolimnion

will minimize the impact of anaerobic nutrient regeneration (Mort imer

1941, 1942; Fillos and Molof 1972). Alternatively, restoration tech-

niques, such as dredging to remove nutrient-laden sediments f rom the

reservoir or hypolimnetic aeration to increase dissolved oxygen levels,

may limit oxygen depletion in hypolimnetic waters.

Changes of redoxstatus in reservoirs

17. In an aqueous system, the degree of oxidation is limited by

the electrochemical potential at which water becomes unstable and is

oxidized to molecular oxygen (Baas Becking et al. 1960). Within the

limits imposed by the stability of water, oxidation states of elements

are affected by redox potential. The measured redox potential is

largely determined by a few of the more abundant elements (Bohn 1971).

18. Stumm and Morgan (1981) and Bohn (1971) emphasized that

natural waters are in a highly dynamic state. Measuring the redox

potential in natural aquatic environments may lead to erroneous results

because no single oxidation-reduction potential (Ell) electrode can re-

liably measure the redox potential. For example, Ell is inaccurately

measured by a platinum electrode it, oxygenated natural waters because

the electrode is unstable in the presence of molecular oxygen.

13

19. Microbial activity can alter the oxidation-reduction status

of reservoir waters. In the presence of oxygen, autotrophic microbes

(including nitrifying bacteria, ferrous iron-oxidizing bacteria, sulfur-

oxidizing bacteria, methane-oxidizing bacteria, and hydrogen-oxidizing

bacteria) derive their energy from oxidizing reduced inorganic compounds.

These microbes depend primarily on CO2 fixation for their carbon. Prin-

cipal components of a biochemical redox cycle in aquatic ecosystemh are

listed in the tabulation below.

Microbial Principal Energy Source ElectronProcess Reaction (Electron Donor) Acceptor

Nitrification Nit 4 NO3 Nit+ 0.

S oxidation 4 HS 02

Fe oxidation Fe + 2 Fe+ 3 Fe+2 0.)

Mn oxidation Mn+2 M nl4 Mn 2 02

Chemical transformations inaquatic environments duringreaeration or destratification

20. In the presence of oxygen, biological decomposition of or-

ganic matter proceeds rapidly in a sediment-water ecosystem. Oxygen

may be introduced into anoxic water by hypolimnetic aeration or natural

destratification. Introduction of oxygen changes the redox status ot

anoxic waters and may reduce the solubility and/or concentrations of

various nutrients and contaminants in the water column, thus eliminating

certain adverse conditions associated with eutrophication (Mart in and

Meybeck 1979). A dissolved oxygen concentration of about 5 mg/l. has

been successfully maintained in the hypoliniia of small reservoirs by

artificial oxygenation (Fast et al. 1975; Smith et al. 1975).

21. The following section briet ly describes nutrient and

contaminant cycles in aquatic ecosystems and the respect iy" oxidat ion

processes.

22. Carbon. A carbon (C) pathway in an aquatic environment is

14

021

outlined in Figure 3. Details of methane(CH4)-production processes in

reduced sediments have been clearly proposed and documented by Stadtman

(1967). Stratified reservoirs normally do not produce large quantities

ATMOSPHERECH4 CO2 O2".

0t

WATER AQUATICFLORA

DECOMPOSITIONOXIDATION A

CH4 ECO2 RTL.k REDUCTION COMMUNITY

SEDIMENT TOIFFuLsONCH4

REDUCTION CO2 DESORPTION

Figure 3. Outline of pathways of carbon in aquatic environments

of methane if the sediments contain dissolved sulfate. Theoretically,

methanogenesis does not start until sulfate is completely depleted

(Ponnamperuma 1972). Carbon dioxide (CO 2 ) is then utilized by microbes

in the methane-forming process in a highly reduced aquatic environment.

Increasing temperature enhances methane production (Mallard and Frea

1972). No significant methane evolution was detected at temperatures

at or below 10C during a reservoir simulation study in a WES labora-

tory (Chen, unpublished data).

23. Internal carbon cycling by methane oxidation in aerated

aquatic environments occurs in a narrow band within the thermocline

during summer stratification (Patt et al. 1974; Rudd and Hamilton 1975).

Methane, which is biologically inert in the absence of oxygen, can be

converted to carbon dioxide and cellular material in the presence of

oxygen. Several field studies (Reeburgh 1969; Howard et al. 1971) have

15

-I:

confirmed that methane is always present in the anoxic bottom sediment

and is released to the overlying water. Estimated methane cycling in

Lake Mendota, Wisconsin, is summarized by Fallon et al. (1980) (see

tabulation below*). High diffusion rates of methane through sediment

seem to contribute to an increase in methane oxidation rates, and

methane oxidation rates in aquatic environments increase as the con-

centration of oxidized inorganic nitrogen increases. In Lake Mendota

during summer, for example, the methane oxidation rate was approximately

23.3 mmol/m 2/day--a rate equivalent to 45 percent of the methane produc-

tion rate in anoxic sediment (Fallon et al. 1980). During destratifica-

tion in the fall overturn, the concentration of total methane in Lake

Mendota waters decreased by 90 percent. Methane oxidation in Lake

Methane Cycinz_Carbon2mmol/m Percent Methane

Process

Methane oxidized 999.5 45

Methane released toatmosphere 181.7 8

Hypolimnetic methaneaccumulation 1,028.8 47

Total methane produced 2,210

Carbon CycI i n&Carbon.) Percent CarbonmmolI/ /,day Sedimented

Process

Methane produced bydeep sediments 35.8 54

Sedimentation ofparticulate organiccarbon b7.5

Material reproduced by permission of American Society of Limnologyand Oceanography, Inc., Grafton, Wis.

16

Tanganyka, East Africa, a deep meromictic lake, occurred mainly within

a narrow zone at the boundary of the seasonally mixed layer and the

permanently anoxic bottom waters; the methane oxidation rate there

varied seasonally from 3.8 to 5.8 mmol/m 2 /day (Rudd 1980). Howard et al.

(1971) noted that the methane oxidation rate may actually be much less

than actually measured, since most of the studies were based on isolated

systems in which the substrate was not continuously renewed.

24. Nitrogen. Lake sediment is generally considered to be a

nitrogen (N) reserve in aquatic environments. Total N contained in

surface sediment may range from 0.1 to 4 percent, depending on sediment

characteristics and calcium carbonate (CaCO3 ) content. The nitrogen

cycle in an aquatic environment is strongly influenced by the dynamics

of a particular lake. The nitrogen cycle in a sediment-water system as

outlined by Chen (1971) is shown in Figure 4. The net concentration of

various N species depends on the rates of N immobilization, mineraliza-

tion, nitrification, and denitrification. In bcttom waters of strati-

fied eutrophic reservoirs, nitrate (NO3 ) declines to nil as oxygen is

depleted and ammonium (NH+) begins to accumulate during summer stratifi-

cation (Hutchinson 1957). High NH-N levels in anoxic bottom waters+

are caused by release of NH from sediments and decomposition of set-4

tling sestonic material (Serruya and Berman 1969). Therefore, under

anaerobic conditions, net N mineralization is characteristically

greater than under aerobic conditions (Greenwood and Lees 1956).

25. Aeratioii of an ammonium-rich hypolimnion will lead to the

disappearance of NH and the formation of oxidized forms of N. The net4

reactions are expressed as

+NH 4+ 20 2 4 NO 3+ H 2 0 + 2H1

The aerobic conversion of NH + to NO is a normally considered as a first4 3order reaction (Endelmann et al. 1973; Misra et al. 1974; Selim and

Iskandar 1981) . Hall and Murphy (1980) demonstrated that nitrification

is zero order for substrate and first order for microbial activity.

17

ATMOSPHEREEXTERNAL N SOURCES

GASEOUS N I

N FIXATION N0N

BIOMASS NINO2

WATER /'* / IMMOBILIZATION

PARTICULATE AND SOLUBLEORGANIC N NH ----- p NO- NO3\AMMONIFICATION NITRIFICATION

.Em..*....one ........ EWm ENMEUEEEUUE

BIOMASS N _______ NH+ ISOLUBLE EXCHANGEABLE4

SEDIMENT 11

GROUND WATER

Figure 4. Outline of pathways of nitrogenin aquatic environments

However, nitrificationi reaction was proposed as a zero or a pseudozero

order reaction by others* (Wong-Chong and Loehr 1975). Oxidized forms

of N produced from NH +oxidation do not appear until about I week after4

aeration (Chen and Norris 1972) because biological reactions domillate

the conversion of Nil+ to NO in aqujatic environments. Nitrification has4 3

been shown to be carried out by both autotrophic and heterotrophic mi-

crobes. Conditions at the water-sediment interface have a ma joc impact

on the N balance of aquatic environments (Keeney 1972, 1973): it sedi-

ment or bottom water has a high oxygen demand, nitrate rapidly di1s-

appears once the supply of oxygen is discontinued. Unless the bottom

Personal Communication, S. W. Johnson, 1978, Research Assistant, KeckLaboratory, California Institute of Technology, Pasadena, California.

18

waters are compl etely ariox i c ,l fLt ri fI i cat ion shoi d proceed isj t above

the water-sedimient interface (Lee 1970).-

26. A field study ((lien ci al . 1979) demonistrate~d that iritri fIi-

cat ion beg ins soon after ot-rat ion of theC damiiion iuIir- en ri chedf hYpol Iinih ioii

However, nit rate format ion iii a st rat it ied reservo I r is I ii ted to a few

weeks due to tile dep let i on of ammon i umn (Wi rthI and Dunist I 9b 7 , Chen e t a I.

1979) . Addi t iona 1 ainmoni un relIease d f rom seti imients% d ur irig aterat i oin

would not be s i gn it i cant because N iinmobi I i za t ion i s enhancriced i ii t lit

presence of oxygen (0,)).

27. Nit ri ficat ion, dten itri ficat ion , anid NQ ir(1111obi I IIza t r on Inia

p roceed simul Itaneously iii aln aerated hypo Iiin ion , but NHt 1 Ilirirob 1) 1 1 1a -

t ion p robabl1y is minlim alI (Keeney 1972) . A noriqua ntit at i e conlve r sion

of NHt to NO, indicates that derrit rit icato joi edian i sins operate ill4 -3

aerated hypol1ininret ic env ironmen t s. Acciumu I at ion of NO.,) 01115t alIso be

cons ide red in tilie ove rallI N ha Iainct because the lack of inic rob raI popi -

1 at ions inl the water col umn rray result iii NO., accuml Iat ioil. III an1

elt roph ic i mpounidmenit, B rezolli k anrd Lee (1 968) estimated t hat the raiteC

of nit rogen di sappeararnce , presumably due to tieriit r t ikat ioil, was

approximiately 0.32 ig N/L/day.

28. Phosph-orus . The rate at wh ichi seim ienit akt s as a sellrcev or

s inIk for phosphait e-phospho mis largely depernds oil tilie redlox statu 11 ,ii

pH of tilie aqua t ic env ironment . The imos t importaint to rms of pliosplio rul

in lake sed iment are, bound in amorphous i roll hvdroxy complexes ( Sver~s

ci al . 1973). Rural runoff , wasteuater discharge from ir1LuriicipJ I ari

indus trial sources , arid uirbani riiro ft are gene raIlly the mrajor phosphlat e

(P 4 3 ) sources for lakes and reservoirs (Lee, 1906) ; prec ipi tat ioll arid

4 --3

systems. Release of PO0 from sedimnt to water is highly correlated

with the i ron content of surf ace sedinment . Syers et aIt. (1 97.3 r evirewed)

thle PO4 cyclIe ill a water- sedli men I system eiialid ou t I i ned thle pliospho rolls

(P) cycle as dep ictedl by thi tll o inrg schematic pathlway (Figure S).

29 . In recent years , it has bneen gene ralI ly conicIitided that sedl r-

merits canl act as a buiffe(r to ma inta in a certain level of P0- iii overl-4

lying water (Pomeroy et -it. 1905; Stnimni and Leckie 1971). Phosphate

Pi Po

P ARTICULATEI PARTICULATEI~Pi ~ SETTLING, P

EXTERNAL 0N WATER MIXING L% INTERNAL N

PHOSPHORUS SEDIMENT DIFFUSION PHOSPHORUS

PHOSPSHORUS!SSEDIMENT- EIMETPARTICULATE PARTICULATE

" SEDIMENT- SEDIMENT-

DISSOLVED DISSOLVEDS Pi Po

Figure 5. Interchange between water and sedimentP compartments (P. = inorganic P; P = organic P)(from Syers et al. 1973, reprinted By permissionof the American Society of Agronomy, Madison, Wis.)

transport across the sediment-water interface or "active sediment layer"

plays an important role in the phosphorus status of lake waters (Arm-

strong 1980). The rate of transport is controlled by the physical,

chemical, and biological characteristics of the aquatic system. The

enhanced release of sediment P under anaerobic conditions is well docu-

mented (Golterman 1977); increasing temperature or lowering the 0 con-3 2

centration in the overlying water increases PO release rates (Holdren4 -

and Armstrong 1980). Sediment resuspension removes dissolved P043 from

the water column; however, a more dispersed state of the suspension may

result in a higher level of particulate inorganic P in overlying water

because of the presence of colloidal inorganic P. Release of inorganic

20

P from sediment to the overlying water is influenced by the forms of

inorganic P present and by the rate and extent of the interaction of

these forms with the aqueous phase (Syers et al. 1970, 1973; Ryden et al.

1973). The importance of the P contribution from sediment to the over-

lying water will decrease as lake depth increases and lake surface

decreases.

30. Redox potential plays a major role in the chemical and physi--3 -3

cal mobility of PO in water-sediment cnvironments. Release of P0444

from sediment to water is highly dependent on diffusion rate and turbu-

lent mixing (Lee 1970). Iron in surface sediment and hypolimnetic water

undergoes oxidation from ferrous (Fe + 2 ) to ferric (Fe 3 ) as anoxic hypo--3

limnetic waters pass through an oxygenation cycle. Adsorption of PO4

on ferric oxides is particularly important in regulating inorganic PO4

mobility in overlying water (Mortimer 1941, 1942; Williams et al. 1971;

Shukla et al. 1971; Holford and Patrick 1981); in fact, radioactive

tracer studies on the movement of inorganic P0 3 between sediment and

-3 4

water show that P0 concentrations in overlying waters are mainly reg-

ulated by sorption reactions (Mayer and Gloss 1980, Mortimer 1941, Lee

1970). Lake sediments can serve as a source of P04 3 to overlying waters

under certain environmental conditions, even when oxygen is present in

the overlying water. However, retention and release of P04 3 from sedi-

ment to overlying water under various Eh conditions are still unclear-3

since PO is not directly involved in redox reactions in aquatic envi-4 -3ronments. Release of P0 to water increases with temperature increase;

temperature effects are most pronounced in calcareous eutrophic sedi-

ments (Holdren et al. 1977). Holdren et al. (1977) contend that the

observed PO 3 release from sediment to the overlying water probably re-4

suits from a decrease in the sediment redox potential instead of from

increased dissolution or desorption of P0 3 from P-retaining components4

in noncalcareous sediments. The increase in temperature increases micro-

bial activity in calcareous sediment, thus depleting 02 in the intersti-

tial water and reducing ferric iron to ferrous iron, with subsequentrelease of PO-3 . Vollenweider (1976) estimated that therelese f P0 Volenweder(196) etimted hatthephosphorus

4 2regeneration rate was 9.6 mg/m /day from an anoxic sediment in a

21

eutrophic lake. A much higher regeneration rate (up to 18 mg/m-/day in

Canadian lakes) was reported by Lean and Charlton (1976). The average

release rate of P043 from sediment ranges from 0.62 mg/n /day in northern

oligotrophic soft water lakes to 51 mg/in /day in calcareous eutrophic

lakes in southern Wisconsin (Holdren and Armstrong 1980).

31. Iron. Although iron is abundant 11 natural water, most iron

forms are poorly soluble. The available iron content of hardwater

calcareous lakes is extremely low (Wetzel 1972). Sediment organic

matter and chelating agents affect solubility and precipitation of iron

in an aquatic environment. Redox pathways of iron and manganese in the

aquatic environment are shown in Figure 6. The presence of sulfide in

a natural water system indicates that Fe + 3 has been completely reduced+2 +-2

to Fe , with some or all of the Fe precipitated as FeS.

ORGANICCOLLOIDALCOMPEXE FeOH)3- nH20GROWTH

WATER '02 HOMOGENETIC S203 -SO4 +S o

-- Fe* 2 + S= 02 S03 0Mn Mn+2 + S= 4

02 HETE ROGENETIC,

CLAYS, MINERALS, ETC.

INORGANIC COMPLEXES GROWTHAND PRECIPITATION n H20 SORBED Fe(OH) 3M 'C3 , FeCO

3 tII

P04

SEDIMENT IRON PHOSPHATE GRAVITATIONALSETTLING

Figure 6. Outline of pathways of iron andmanganese in aquatic environments

32. Introducing 02 into an anoxic aquatic environment will result+2

in the rapid oxidation of Fe to its ferric form as outlined in the

following expression:

22

N

2Fe + 511.0 + 0 = 2Fe (Oi) i (s) * 411

This react ion is ext remIely sells it ive to 0, (Alexander 1961), rid the

stable metal bonding may be eons idered irreversible in an aerohi sys-

tem. In an acid envi ronment , where auto-ox idat io o I Ierrous I roil is

not possible, the ac idoph i it i croorgal i sills inc Iid Iig lhi oba iI I us

(Ferrobaci I Ills) terrooXydanus can chemoa utot rophi c'a I I v colvert Fe + to

Fe+ 3 . Mlany other heterotrophic iron- and Inagant-se-oxidlz ing batter Ia

also colt ribute to the format ion of i rol and manganlese oxides ill lake

sediments (Wetzel 1975). Under netitra1 conditions, the rate of terrous

iron oxidation is first order with respect to the concentratioils of

hoth ferrous iron and oxygen, and second order with respect to hvdroxide

(Ghosh 1974). Oxygenat ion kinet ics of terruls i roi are reviewet anid

sumniari %ed by Sung and Morgan (1980) (see Table I) The ki net ic equat ioni

for f rrous i roli oxidat ion is generally expressed (Stnim aid Lee 19t1,

Morgan and Birkner 1966 ) as:

,t.1 Fe(ll)J 2 F ~ l ] [0 ] [ 1- 3d t I- k I Fe(I I)j 10) 1 10 - C (3)

where

k = the oxidat ion rate constant

= I molar concentration or act ivity of suhstrate

t = time

Sung and Morgan (1980) proposed the following general r.ite law in car-

bonate buffered solutions when pH is less than 7:

2

d IFe(lI)] = k IFe(lI)1 IPO A ImH I (4)

The variation of k with different alkalinities is due to differences

in ionic strength and solution temperature.

23

33. The low solubi Iity of i ron oxides precludes high concentra-

tions of iron in an aerated aqueous system. Thus, oxygenation of iron-

enriched hypolimnetic water can significantly decrease solubility of

ferrous iron (Symons et al. 1970).

34. The influence of pH and redox potential on the valence state

and speciation of iron in a simple aqueous system is shown in Figure 7

(Krauskopf 1967). A marked interaction between redox potential and pH

in controlling iron (Fe) solubility in soil solution systems was

described by Patrick and Henderson (1981). High solubility of iron in

an acidic aqueous system may have a great effect on Fe concentration in

reservoir waters receiving acidic mine drainage. Ponnamperima et al.

(1967) confirmed ferric oxyhydroxide (Fe(OH)3 ) and ferrosoferric hydrox-

ide (Fe (OH)8 ) participation in redox equilibria in flooded soils.3 8

Van Breeman (1969) reported that the equilibrium between ferric and

ferrous iron was largely governed by ill-defined ferric oxides which

were intermediate in stability between amorphous Fe(OH) 3 and lepido-

crocite (y-FeOOH).

35. At steady state in groundwater (Ghosh et al. 1966) or

water with chemical additives, the Fe + 2 oxidation rate k is estimated

to be 2.01 x 1010 M 2 atm-1 day 1 when the ionic strength was ad-

justed by NaCIO to 0.020 M (Sung and Morgan 1980) at 25 0 C. The mean4 +2

residence time of Fe varied from 4.3 to 54 minutes (Ghosh 1974) tinder

aerobic conditions. Since most natural waters have alkalinities less

than 300 mg/L as CaCO3 , poor buffering capacity lowe rs the oxdatlton

rate. Under acidic conditions (pH = 3), half-life tine for ferrous iron

oxidation is about 1000 days.

36. Surface ionization and comlexation on ferrous hydroxide

(Fe 03 H 0) (amorphous) and some hydrous oxides of metals at the oxide/2 3 2

water interface affect the absorption behavior of dilute heavy metal

ions (D)avis and Leckie 1978). This explains why the concentration of

F+2 +' echece( i-15 --IFe and Fe 3 must each exceed 10 N L-/1, (0.56 mg/L) to govern Eli

(Coursier 1952). In a study of redox potential of the Fe(OH) 3 - Fe + 2

system, Nhung and Ponnamperuma (1966) found that added Fe(OH) 3 was

stabl e in a flooded soil system when redox potential was above +200 mV.

24

(D SOLUBLE TOTALSPECIES ACTIVITY

1400 iRON 10-6 MC -- SULFUR 10 6 M

1200 CARBONATE 1 M

1000

> 800 Fe' 3

E

* 600I- k-02

,,,u 400 - F+ ,, Fe20 3 H2

x 200 -00 H

-200 -

-400 - Fe++

-600FeC0 3 Fe3 04-600 - k

0 2 4 6 8 10 12 14

pH

Figure 7. Redox potential-pH diagram indicating thestability field of common iron compounds (adaptedfrom Krauskopf 1967, reprinted by permission of

McGraw-Hill, Inc., N. Y.)

37. Organic matter and other decaying vegetation can retard

oxidation of ferrous iron even when dissolved oxygen is present. In the

presence of iron-organic matter complexation, tile Fe +2-Fe + 3 redox couple

acts as an electron transfer catalyst for the oxidation of organic

matter. Complexation of iron and organic matter increases as pH and

the organic-Fe +2 ratio increase in aqueous systems (Theis and Singer

1974). The following diagram outlines the ferrous iron oxidation pro-

cess in the presence of organic matter:

25

2 +2Fe (II) -organic matter 02 Fe (111) -organic matter Fe + oxidized

reii t t i

organic matter organic matteri c

Fe+ 2 02 Fe+3

Fe(OH) 3

38. Manganese. Oxi(ation-reduction conditions and ptl are Lwo

major factors that a ffect the di st ri but ion and so Iubi i ty o I manganese

(Mn) in an aquatic environment. An outline of manganese redox Iathways

in al aqueous system call be expressed as

exchangeable form

1 acid or slightly acid

Mni+2 Mi Mi organ i c (oml)1 exreducible, insoluble form } neutral or OH-

precipitated as MinCO1, MnO, MnO.,, or Mn(lI) 2

residual form

39. Under all pH conditions, water-soluble and exchangeable forms

of Mn predominate in an anoxic aquatic environment. Compared with otlie+'

metals, the organic-Mn complex is relatively unstable. Although M11n+3 ndn+4 +2 +

Mn 3 and Mn +exist in natural environments, only Mn + and Iul+ 4 art

important (Gotoh and Pat rick 1721). Manganese is normal ly present in+2+

anoxic soil solutions as Mn , MnlHCO+ and as organic complexes. The

complex nature of chemical and mictobial processes in natural aquat ic

environments makes it diff icult to explain the behavior of manganese in

terms of a simple chemical system.

40. Dissolved, reduced forms of Mn - accumulate in an alioxic

hypolimnion, while very little soluble Mn is found in the oxidized sur-

face water during summer strati ficot ion (lHutchinson 1957). Patrick and

26

.' E.n _ __ _ _ _ .

Henderson (1981) concluded that soluble Mn is responsive to ptl, but

they showed no precipitation of Mn in a short-term oxidation study.n+2

The process of Mn oxidation appears to be similar to that of iron,

although occurring at a much slower rate. However, at low concentra-+2 +2

tions Mn oxidation does not occur as readily as Fe oxidat ion withi

the pH range of most natural waters. During or after destratification,

soluble Mn+ 2 diffuses from reduced sediments to the oxygenated inter-

face, is sorbed by Fe + 3 and Mn+4 oxide hydrates, and is oxidized to

produce Mn-enriched nodules (Ponnamperunia 1972). Sine terri c oxides+2

have a high sorption capacity for Mn , it is likely that a considerable

portion of the Mn can participate in the dissolved-particulate cNV le

without undergoing redox reactions.

41. Transformation of soluble Mn +2 in a CE reservoir (Fal Gal Il

Reservoir, Wisconsin) were studied during 1980, and the results are pre-

sented in Figure 8. Manganese (II) was detected in Eau Gat, Reservoir

waters even when oxygen was present. Reduced mangnatiese ( I I ) was al so

observed in Lake Mendota, Wisconsin,, wa te rs coricurreritly with oxygen,

by l)elfino and Lee (1968). l)estratitication or aeration, which maidt'

more oxygen available, reoxidized most reduced Mn and Ve to insolublt'

oxides which were then deposited on the sediments. Oxid'it it) o1 redlt ed

manganese was also illustrated by the formation o1 black manganese di-

oxide (MnO 2 ) on rocks in the tailwaters of dlams which release water trom

anoxic hypolimnia.

42. Products formed from the oxidation of Mn undle'r Va r ious

pH conditions are nonstochiometic and amorphous. Manganese (11) oxda-

tion reaction rates are strongly pH-dependent. The average manganese

oxidation state can be represented by MnO1.90 (Morgan 1967) or by

Mn + 2 .3 -2 .7 (Hem 1981; Emerson et al. 1982). The disappearance of re--

duced manganese in oxic conditions is an autocatalytic reaction in

aqueous systems (Stumm and Morgan 1981). A solid phase able to absolb

Mn+ 2 ions greatly accelerates the reaction by facilitating the surface,

+2 +4electronic transfers from Mn to Mn . In the Cox Hollow Lake

system, Wisconsin, about 40 to 50 percent of the hypolimnetic Mn+ 2 was

associated with particulate matter in the entire anoxic water column

27

16

12

h DO

4Mn

4

00 50 100 150 200 250 300

DAYS

Figure 8. Changes in 0 2 and soluble Mn concentrations with timein the overlying waters of a stratified CE reservoir

(Brezonik et al. 1969). In contrast to these findings, Delfino and Lee

(1968) reported that the major portion of Mn in Lake Mendota was in the

soluble form.

43. The kinetics of Mn+ 2 oxidation rate may be expressed as:

d [Mn+21 = ko [Mn+21 + k I[n +2 lInO 2 1 (5)

dt

where k and k are rate constants. Stumm and Morgan (1981) sum-

marized the rates of Mn+ 2 oxidation in an aqueous system as follows:

+2 slowMn + 1/2 02 MnO2 (s)+2 + Mn fast +2

Mn + MnO 2 (s) Mn .MnO+ 2 (s)

+2 slow

Mn MnO 2 (s) + 1/2 02 2 MnO 2 (s)

28

where s = solid. The relationship between Mn+2 oxidation rates and 02

concentrations is the same as that of Fe and 02 concentrations, so k

in Equation (5) can be formulated as:

2k = k' IOH I PO2 (6)

44. Oxidation pathways for reduced manganese in natural water

was illustrated by Bricker (1965) and Hem (1981). The net process can

be summarized as:

1. 3n + 2 + 1/2 02 (aq) + 3H 20 = Mn3 04 (c) (hausmannite) + 6H+

2. 2Mn+ 2 + 1/2 02 (aq) + 3H 20 = 2MnOOH(c) (manganous manganite) + 4H+

where c = precipitation. The reaction rate is then expressed as:

d [Mn+2] = kl IMn+ 2 1 + k2AMn ppt Mn+2 (7)

where Mn+2 represents thermodynamic activity of dissolved unreacted

manganese and AMn ppt represents the availability of reaction sites on

the surface of the precipitated manganese oxide. Both hausmannite and

manganous manganite further react to produce one of the forms of MnO .

45. Formation of an organic-Mn complex can enhance colloid sta-

bility when hausmannite and manganous manganite settle from the oxic

zone onto the surface of an anoxic sediment. Manganous manganese

(Mn 2 ) is removed from aerated water when it is oxidized to Mn oxides.

Manganese (II) might also be adsorbed onto suspended particles such as

particulate Mn or ferric oxides (Bewers and Yeats 1978), or incorporated

into complex particulate matter matrices. Physical settling of these

particulates would account for the observed loss of Mn from the water

column and would slow oxidation rates. The main mechanisms for Mn+2

removal from aerated water are a combination of oxidative precipitation

(Graham et al. 1976), sorption, and complexation reactions.

29

46. Sulfur. Sulfate can he totally depleted while hydrogen sul-

fide or reduced sulfur can accumulate in anoxic hypolimnetic water and

sediment during summer stratification. Laboratory results bave shown

that sulfide (from detrital sulfur) in anoxic surficial sediment is usu-

ally liberated during the first few months of anaerobic decomposition.

Poorly soluble compounds containing sulfide and heavy metals may be

formed in anaerobic environments (Jorgensen 1977). In fact, the

inorganic chemistry of anoxic water near sediments is dominated by

ferrous sulfide precipitation (Davison and Heaney 1980). At IOC, the

solubility product for ferrous sulfide at near zero ionic strength is-17

0.9 to 2.0 x 10 ; this is similar to a laboratory value for amorphous

ferrous sulfide (Berner 1967). Oxidation of sulfide occurs in the pres-

ence of oxidizing agents; the presence of ferric hydroxide or geothite,

for example, will oxidize H 2S to elemental sulfur which can then be

further oxidized to a saturated polysulfide solution (Berner 1963).

Sulfur oxyacids (S 03 ) are theoretically either unstable or metastable2 3

despite their detection in measurable quantities in natural waters

(Jorgensen et al. 1979). Sulfate is the most stable main end product

of the sulfide oxidation process in aerated waters, irrespective of pl.

The reaction pathway, of sulfide oxygenation was summarized by Chen and

Morris (1972) thusly:

+HS

-2 Chain Reaction -2 22so 0+ sos

+02 3 +0 2 4

S -2 -- So -22 3+02 4

+H0 s+o 2 o2+HS 30 4

+0 2

47. This reaction pathway indicates that chemical sulfide oxida-

tion occurring at the anaerobic-aerobic water interface undergoes a

30

sulfide-stl fur-polysul fide cycle. III it ial oxidat ion of suitide to0

sulfur is a possible rate-determining step. J~rgensen et al. (1979)

demonstrated that dissolved oxygen and H.S could co-exist iII tilt inter-

face between oxygenated and sulfide-bearing waters.

48. Oxidation of sulfide in lake and reservoir environments is

mainly biologically mediated, but chemical oxidation can occur (Engler

anti Patrick 1973). The reaction pathway shown previously is applicable

only to chemical oxidation; biological sultide oxidation to sultur can

eliminate the rate-determining step of initial sultur formation. Both

chemical and biological factors may subsequently play a signiticant rolt,

in further oxidation. Numerous attempts have been made in recent years

to determine the kinetics of sultide oxidation iii freshwater systems.

However, results of these investigations show considerable disagreement

(Hoffmann and Lim 1979). Evidence indicates that sulfide oxidationn+2 +

rates are sensitive to trace metal catalysis by Mir , Fe 2 , and other

reduced metals (Chen and Morris 1972). Eventually the oxidation is

also catalyzed by homogenous and heterogenous organo-metallic complexes

in natural aquatic ecosystems (Hoffmann and Lira 1979). Oxidation of

both sulfide and manganese can also be affected by the presence of ka-

ol inite, montmori 1 lonite, Fe(OH) 3*n H20, and part iculate organic matter.

49. Art in situ study using a radioactive tracer technique ind-

cates that sulfide is subject to rapid biological oxidation and has a

half-life of 5-10 min, producing mainly sulfate and thiosulfate in

the chemocline under both light and dark conditions (J~rgensen et ai.

1979). The rate of oxidation to sulfate for intermediate compounds in

sulfide oxidation is greater for S 40 6 less for S 20 , and least for So

(Wainwright and Kiltham 1980). The kinetics of aqueou, sulfide oxida-

tion by 02 is pH-dependent (Chen 1972), and oxidation is stimulated by

the presence of NO3 (Wainwright and Killham 1980). The sulfide oxida-

tion rate is slow under acidic conditions (pit , 6) where H 2S is tile

predominate species. The oxidation rate initially increases with pit

and reaches a maximum at pH 8, then decreases to a minimum near pH 9;

the rate increases again as pH increases to near 11, and decreases

under more alkaline conditions.

31

Fqtu i I i hr urni Modev Is IDepi ct Iii Atrot)i c P rocvss'N

Wajte r qua~i I t y mode I Iing

50. Use of tile current version of the CE-QLIAL-RI wate'r clual itv.

modlel indlicated that its lack of general I tv and chemli cai I oriviltat loill

l imited its use as a1 predict ive tool for waiter quIAI Ity inl CE- reservoi rs.

ther ex ist i rig water qua I i ty model Is we re rev i veei andIl eva I olat vd to or

the ir teas i hi I i ty use as .I stibrouit tilt te for- t he CE-QIIAI-R I model to s I mu-

l ate vLte t ratist tormat ioll- of cetmi ica I COu[StI it tiit undIller VAi r I ous I ron0 1d I -

t ions, norma IIy f ound Iin CF. reservoIis ; the rt'su It I ug s ingl 1,inIttegrated

mode I (CE-QIA I. -R I + aerob ic suibrout Ine ) woulId he vno it' use I itI thlan se-ve ra

overlapping modelIs. As a consequence ot Ia workshop onl dilOvedpat

ui late- i nteraict 01oils, thle cheivi calIt oq i I i hr i ium molt)(t M I NFQ. was iiniit I I I I

Ie ectedf as a has Is for- WES ' S aerob i C Chiemli k I I hia cter i zat i ol. lT'e

REDiEQtL2-M I NEQt.-t;F.OLIIEMI se ries of relt ted chlim1i t'qniliii-i urn ode Is

(-anl prov'ide I lexiti Itiland compirehieniis vippromAwhs jietulel to stud iiv wter I

quali ty in CE- reservo ir ecosystems, aIt hough a decision was Illidt' re-

cent I y to dfeve lop a rate model I for Llte IVIrOh I C stihr-oiit ic 111 theit

CE-QULI-R I nodte I ( see, pa ragraph 6 1 ) . A hir Iet d i s cuss i oil of t liest' cdiemi-

c alI etiln I I i hr 111i un ode I Si S presented 1LIt, t 0 to I lig S'ct I Oi.

RE)EQ L2

5 1 . RE.DEQI,2 (McI~u ft aI tilt o ire 1 19 75 )1 i s a t olillti t t, r- p ro g raml

w r I t t en Iin FORTRAN I V anti i s ma Iit Iv iit edt to (-.Il c ii la teI rmii ri I t'qui I I 111-

rl, Il a(UOI ii tit5systemIs. The, pr inmci pal a1pproach of the program is hased

onl thet Nt'wton-Raphisoi met hotd (Conte aind ttt'Boor 1972) for- digital romtii-

tat ion of chemical equ1iirium. Chemicral compouinds or rompltext's i

des ignatetd aqueous systemis are iexp rtessedt as f unict i oi of f rte mt' t anid

t ret' I igand conce'nt rat ion. Equ iIibhr iumn constaiit s hased onl "crit icalI

stabii ity constant s" (Martell anti Smi thi 1976-77 ) for each indet-pendenit

react ion amre stored Ii the program to catlcula te' rate-hal anie reltat ion-

sIp Is . REDEQ.2 ( I ngle v t a I . 1978) has thet tdata nect'ssalry to compitte

sot 01)i I I ty and comp I txat I on reamct ins htetween 35 me'ta I s and 58 I i gands

REDR.QI,2 (-,Iin a I s o c alI( cu a te 24 s tanda (lit c oup It' vs oft r' do x rea ct Iins;- i xt'tti

s o I Ii I reat i onis . stiit a s chIt Ionr t v I I i v 1 tt'. mIi c roc I ite, at i to Iom I t v

and ad(s orpt ion and (IeSO rpt i on (it met a I i ons on nipet a I ox ides A comrpletet

the rmodytam i cdat at deck intc I odes at p rogr ramt o f cheicalI equ i I ii r i ti n

aqILeOUS systemIs i nco)rpo rat ing at sys tem of 788 sotlublec species , 83 possi -

hi e solids , and a gas-phase comlponent (Mo rel anrd Mo rgan 1972). REDEQL2

was applied by H-ot fmann and E isenre ich (1976) to predicet the re lat ion-

ship btetweent Mn +2 and Fe + 2 tin the hypol imniori of at stratiflied southern

Wisconts in lake and by Morel et al. (1975) to model the concentratijon

of trace mnet a s tin wasttewa ter discharge. REI)EQL EPAK(, a version of

REDEQI.2 intclurdinog temiperatuore correct ion for equ ilibr i um constants,

was deve loped recent ly by I ng le et al1. (1980).

M INEQL

5 2. MINEQI. was developed Lo provide a compact vers ion of REI)EQ1L2

tor use with smal Iler computers; however, at full-s ize contter ntay be

requ ired to execuite a larger seaale program. MINEQE differs cons iderab ly

f romt REDEQL2 tin to ri t t inrg, but applies much of the same in format ion andl

de f i t i t ioils . Bas i calI I y , t he equ i I i br ium constant method i s usedi in

MINEQL for chemiical equilibrium problems of aqueous systems (Westa I11

et alI. 1976). Thermnodyniamic data stored in MINEQL' s data fi le conttaint

35 metalIs anid 58 1 igantds . Like REDEQL2 , MlNEQL cart be used to study

speciat ion of metals in algal cultuire media, solubilitv constants for

metal eltelates tin complex media, dlegradat ion of iitri lotriacet ic acid

(NTA) tin natural water, and chemical eqtuilIibria in aqueorus soluition

(Westall et al. 1976, Morel et al. 1976).

GEOC HEM

53. GEOCHEM was irtitial ly developed to describe the soil solutiont

system ti its entirety. Tltis compuiter program calculates thte equtilIib-

rium speciat ion of the chemicali elements in a soil solut iort based on

chemical thermodynamics. GEOCHEM is a modified version of iYt)EQL2,

conta in inrg more thtan twice as mutch therrmodynaic data as REDFQL 2 it

utilizes thermodynamic diata selected for soil systems-and employs a (lit-

fe rett stibrout inc to correct thermtodyntami c equ ili bri um cortstants for

the effect of nonzero ionic strength. Stored thermodynamic data include

36 metals and 69 1 igands of initerest in soil solutions.

54. Typical applications of GEOCHEM inclutde: (a) predictirng

3.3

6a:*,- -~.~- .- _ _

the concentrations of inorganic and organic complexes of a metal cation

in a soil solution, (b) calculating the concentration of a particular

chemical form of a nutrient element in a solution bathing plant roots

to correlate that form with nutrient uptake, (c) predicting the fate of

a pollutant metal added to a soil solution of known characteristics,

and (d) estimating the effect of changing pH, ionic strength, redox

potential, water content, or the concentration of some element on the

solubility of a chosen chemical element in a soil solution (Sposito and

Mattigod 1979).

55. Although GEOCHEM identifies and quantifies many of the chemi -

cal species in a soil solution system, it is presently incapable of an

all-inclusive definition of a particular soil solution because (a) inl-

formation on the precise composition of soil solutions is lacking and

(b) the GEOCHEM data base does not contain all the thermodynamic data

needed to characterize the soil system.

Implication of chemical equilib-rium_models__in aatic environments

Sb. Although many computer models have been used to predict and

manage water quality, lack of appropriate kinetic data limits the vali-

dation of ecological computer models. Development of chemical equilib-

rium models for water quality prediction appears to be relatively

straightforward (Morel and Yeasted 1977); but construction of a complete

kinetic model for a natural water system is exceedingly complex and is

further complicated by the lack of kinetic information (Hotfmann 1981).

Construction of comprehensive predictive models that describe natural

water chemistry has to date proved impossible (Pankow and Morgan 1981)

because of the complex and interdependent nature of the many processes

occurring in natural waters. The complexity of natural ecosystems and

their matter and energy inflows and outflows make closed-system equilib-

rium models only poor approximations of a natural aquatic environment

(Morgan 1967).

57. Based on an updated compendium of stability constants

(Martell and Smith 1976-77) and on the extensive experimental data from

research studies on the changes in iron and manganese concentrations

34

during thermal strat ificat ion in a highly productive dimictic lake (Lake

Mendota), Hoftmann and Eisenreich ( 1976) have successt i Illy verified the

capability of a chemical equi librium model, a modit lied version of

REDEQL2 , to predict unus ual sea sona I t rans format ions of t hese e Ielients

in the hypol imnet i c water. Al though appI i cation of the equ i I )r i um

model is limited by the rel iabi 1 ity of ava i lable equi I i bri inm constants,

this revised model is capable of reproduciug rea sonia1)V we lI the , ctual

time-dependent concentrations of Fe and Mn in the hypo limnion A Lake

Mendota during sununer stratification (Hot fmann and EisenirelLi 1981 ).

58. Application of equilibrium models such as REI)EI. 2 and GEiJCHKLI

to analyses of biogeochemical interactions bet weren nutrients and ii ( ro-

organisms in aquatic environments was demonstrated by Giainiat teo et .

(1980). They showed that chemical equilibrium models can be used to

isolate variables and reaction systems. Neverthe less, predictions of

chemical equilibrium models are probably not sufficient to interpret

biogeochemical processes in natural environments. Zimmerman (1980)

examined the feasibility of using REDEQI.2 to predict lead aind phosphatec

transtormations and the effect of pH on the availability of these ele-

ments in an aqua tic environment. Ziminerman acknowledged that linknowin

reaction kinetics were the primary problem in applying equilibrimn cal-

culations; he noted, however, that reasonable agreement between equltil-

rium predictions and actual chemical speciations was indicated by solid

formation when some of the initial assumpt ions were modi fied to acConit

for slow reaction rates.

59. In spite of limited chemical and kinetic intormatlon, ciemiii-

cal equili rium models still provide a useful techni itque to examine the

effects ol hemical interactions in aquatic environments (Freedmiian

et al. 1980). Currently, chemical equilibrium models have been widely"

applied to evaluate the effect of toxicity assays (Jackson and M hrgan

1978) and to analyze biogeochemical processes of trace metals in aujlidtlt

environments (Westall 1977, Sibley and Mori , 1977, Morel et al. 1975,

Morgan and Sibley 1975). Potent ial ut iii o! GEOCHEM in aquiatic ei-

vironments was also demonstrated by Sposito et al. (1980). SposltO

(1981) used the program to calculate the equili nrium speciation in ic id

35

* - *- - --- - - -- _ _

11r cil i t at IoIl IaItud t o pi et I ct t h(e heItav o )r o t so I I Il Ic ue t. I 1 11 t It iiri I

wa ter cenf t adllI I ld t ed by In III ci p.1 I wa st es . ('t~l ic d I equ i I i 1)r um 111 node I s

("In A Iso be. used to p)1red i ct t lie, I it e ract L i o f heavy met al I bet. weeri

.0;1 lt I ol anid Sot I d phiase %'i t. It chianges i n pll (The i s aid il i ch t e r 19 79)

it genera I , t liese mode I s acre powe rt ii I too I s f or p)red ict i rig c hem icalI

rite rac t I oins o f t r a ce mle ta Is wit I i 11u1L i d s arid p)a rt I cn Il a te snl r fa cecs an11d

c ofnl)pet i t i o rIin among mllet a I s i i n a t iira I wa t. crs (Vii ct a n d M o r ga 19iI )7 8).

oP . 'Te p)ra c t ica]Ii o f us i rig clienti i calI eqil i Ii h1r i till ilioute I s ha s

been eva I t ed reetIv y No rds troi et atI . (1980) . Thli r study irfid i -

ea ted good ag reemnrt betweenl mode [ Predict i 015 arid inca Isiired dati a forI

111IaJo - cheivilcalI spec ies iii ho t. I f res hsa t er arlid seawa t er svs t.emis . 'te

peero I agreemiernt tI eno to r the minro r species is p cobab iv Incl to (ill er-

tlict'e I lit' tie riodyriaiic datj a ases used byiv;Iar ilts eqii I h i un

niode I s .No rds t. romn tt a I . ( 1980() Irev i eweit ever1 30 (hem I c-,I I eqil iI i hr r I in

riodelI s id, coric I ted t hajt a g re.)t deal] o f Cani t I ll mts t he txe rc iS std

when aill) lvi rig ani eqii I I it1) r I lint cliin i CJ 1 app reach -tLo Ilit t, rp re t yi~a t. I c

c lierni s t rv . Resca cclhi lives t I ug.i t. I ol Imis t eva I Ila t t, ack-t I v k t I cc I i t

ca I cli Iat ils , redex 'Is suirpt. Iells , t eripeca~it itre cor-ret lor (is, iI Ii it i tv

co rrect i onls, ad othetr emrv i rerimerita I co -rect I oils;reuI t rlei !c (I- ttcriiie-

dvl\'ril ic corls iderit. ionis to lucv I 'It' a Loris I stelit. set oft tIIies .

b~ I . The clieiiirI catI 'qn it ) r I mm noidte I s suitch ItIs' N F NI1.KY I dant ( C4I wI1,

Iasd su oil t Inc ritll(VriIii r Cs- arid used to ca I ciii ate clic'il i Ia I (cqiii I bil hilli

,Iqnteoiis systemls Arid sot I set lut ionis, have hil lit tier I 11I tmiei success Iii

p red I ct I rig secisoia I chaniges anii chieiri ci I Spec iI i oil ol a t ew e Ilient s

It na t iira I water systemrs , eqi Iii hr i It'l niode I s are genlera I iy tiiilih Ice to

aIdequate ty pred ict li tgeocliemita I prO~~'~s . Th i s i s espt'c i at IIv t rile

during thc t rarnsit ion I ren irnatrobirC to wtrehic k ofidit lols ill rest 'll" I rs

when react ionl kinet ics hecont exceingri i mportilt . li such a si tj-

tLion, rate mols which reiy orr kinitt ic tat arte i bet ter choice tor

aiccurately predictinug watterqultv

PAR F II l RF-AFRS - -kEAl-RATI 11)N SUBROUI NE

t) 2. Nat ural d Iest rat it itiat ioin or uIu mela.111( aIl ilt roduc.tijon of oxygen

i nt o aruoxi i t'aqu tat ic env iroim-nlt s ra p il v reox i di zes some reduced( cieni-

1ica I s such as skiIt i de and t erroils iroil di ssto I ve Il or suisp ended( ini the

water column. Other- ox idat ion processes, sto.h 1 s lii t r iti cat i o or

iiarigatious manganese OX idat i on pro( eti sI iv ly.

t) i. This sect ion of the report dc-si ribes, tLtu las 1, st rio. tore of

the aerobic m odelI RE-AERS , or REAERat i on Stibrouut inc. Ilt-ov 'Vra 11I

orgaiiizat ion of the modlt , itLs Various comuponets , andiinitegrait io ofi '

thiese componients are di scuissed lbtelow.

M'ode' I lOrganli zat in .ini Filict I on

t)4 . The ma nner i it whi cli RE-AERS f tirict i oil,, 15siltjui ctt'd ii Fi1-1g-

tire 9 . I ii man,, rese rvo irs , t he rmalI stLicijt i t icajt i oil stLar ts j ind coit i iies

f ro"I'l at e sp r inig, and anaderobi C cond itL i ons develIop ii e a ch wa ter I ave r

In the huypo I i mnii onl ( Fi gu re 9a ) i n the sequienlce pi-roposedI by Guiiui sont and

Brannon (1981). Be fo re dtes trat i f i cat i on o r airti I ic(-ial ae ra t in, lupo-

I imnet i c dIischa rges cont a in (Ii sso [ veil, reducued mangianiese aind i roii,

airnion i um , and t race amoin L s o f- 0t het r redo cedl (hem i (-a I speC- i e s . Due to

pro longed oxygen dep let ioii and the I argt' re(Iiii rement, tor ox id izablIe

carbon sorethe topmost layer 'it h yoifinit otrsror

p robabhiy willI not p roceed heyorir a cc umul I t i oi ol Nil 4 or 'lii (I I

(Gurunison and] Brannon 1981). Methiogencts is wilIl probaibly niever he

found ahove the bottomi sed iment lavers, ,except) ii water di rect ly under

the water-sediment interface (Figure ().

65. In the early stages of destrat if icat ion, a decrease inl stir--

face temperatare increases the density of stirlicial water which sinks

and penet rates the metal imni on. Dest rat ifticat ion occurs when tile depthi

of the epi limnion increases as the depth of the hypol imnion decreases

(Figure 9by. Thie metalimnion is lowered as a result.

06. As the reservoir gradually cools, vertical vater circulation

increases until all lake waters are included in th' ci rciulat ion, and

.17

SDMETINO

SE DIMENIONT

SE DIMENT

d. II oplstaeo of dtratrfiai o DOi s wel te ax reuefoyms g wate~ columnat wit aeute level of on

Figre9. hema statfiatin V

38LMNO

METALMNIO

fall t urreve r beg ins . l)it ri [Ig t hte11 it"il I t ige!; t, I t I t .1 !

s frtIajce watLe r t ha t I ; I lust t o oxyg'tt -s~i t irat Lu 1 rtt11t ces nleet'II fit

th fihypolI imnliIol . twieit ct r- ttlat loll Is" onyIt t te , t he wit e r ret,,1 I it, sit t-

ralt et wi tI 1 oxygen a t t ie la t 1tre- dept'itt'itt levels I t Ft191 g t ) I lt1 gh t tult

cent rat ions ot ds s olIved oXv ge It1. t obsre I n t.(( 11 he ,'iit Irec .itei v r u I tItitI

titear 100) ptreitt si t it rat joltf 1 or st,' ItitI t Ijun ) (llIu tig to olerv mtollt tt

proves ri 1 sso I vt'i oxvlgt'tr l evel I it 1 .1 StI ra t Ii tIed reser\' ItV II. lot tot1. I1

C I rttla t Ioil , t.he told41, ,tirs'x It (- h po I 111i11i oil i II ] tn t -e ( I .It I It thI' w'i IIc[ el I -

I iffmitott to titt reast' oxygenlvl tVt It11 hot tor0n1 t'ICF ; i t t t re W.it c I buody

("Ilt hte t I ftil I 'I t el jIti 'ralt. eel t rotit .i si tIg I t' sItILe , ~I id a I atke wt I I I veti -

tlia I lv Jtt.i lin aj hea~r- tsot hetcmt.) I telPtlI jt Itt rt'gttt[li' 'Tota tII I rt iit t Iol

(1ay v, ittwt've I , comlp Ilett cv I ll tIl~ ti, t it' reslurvo irI 1!s a hai It I at t or ru oI

waitt'r f [sit tltIIr iig the s Ititlt rt It ttlilt as t i but ttton ,. I t c't t etitte 1-,i tit it,

offt the o the r it.,itd, itlt)troves dI s s o eI oX\'gltt toltd t I iits 1t t1ot tttt W ,ttt't

Itt it (It' tts ,1 ofigrt toril It rI teII it .' ('i' to VIgi re 0I bti t e( i i igt

.iitoxtt chot t oit wite C l tIk 1 istta I I y he t (1k. eascd t oi.pplox ImatJ e. Irj i.

by htypolI inmet it' avtrait Illt

EPI LIMNION

METAL IMN ION

AERATED HYPOLIMNION

ISEDIMENT lF igutre 10..l Ater hilll ittti it lrrat ion: t IteI t1alI stI ra t ItI-

lnillttattie it aptrtx imatey Iv ->6 g/I.

X. RF-AV:RS cons I st s tit I I Iiiii t ed iiiiibe r o t Illilses t hiit s1111111 It I.

tlit, tont 1111 n 1 o f mox itc o r ox ct tofil t i If il t ILihe hyplo I I Intl I 11. I tit,

mlode, I rel tIect s Ilerob ic st ages tha t occulr i.,i tlIt at It I e.g . , t 1.Itil I

Alest rat I tI ca I il, hypo I I iliiet. itc ae rat I.on, aind t ot. k tI i( it LoI. l)

NatLural (its t rat i t i (,It I i

Bt,. I [IrII Ing of loss ol strati Iitati il. 'IblI s p0ha1se bieg In It.,l

the oniset. of loiss ot st rati Ii cat ion ill latev suimiler or al f wen at t Im ii-

petat iires betg ill to det I fit,. lDii r- i ig lest I a L I t I (aIt I oi , i'OIIVtLt I'IlII t Cr-

renlts tind epi Iliet it ci rculat ion expand the tli ickiess of thn' oxygen-

bea rirfig I I i ))If of). The leciompos I t I ilu rajteI ot o rgan it ilII]t te(Ir I ni I ca s's

arIld retduce~td diemi cal Itompoilit s o r i g i uia I I V in[ t lie tLop I ave r ol t L h

ii kt hiypo I i i11 il n are ox id iZed. T[he Water to Ihull aliovt th li mt l iinin

rema inus nrirIv sattilra ted withI ox',genll

j ) . 'Il rriove r . Turriover begills wen tie( erit i re 'o Iluie olt I I kc

waiter beginis to ci rtiiate du~ring tIle, tr.llit ion I roii suiniie sti'at i I lcaJ-

io[n to Ci ruitL ion which cali oLcur_ Ill a til ew hurs, d(iis . oi- %,t'i'ks lIe-

peniinig u1pon wIiiid velocityv, Leiiiperajture graidient. , re(SerVo i I. leptIi, IS

t-l'Vi lVd roilynaIiri its, trill ut her ei 0 l'Oiiiirit a I J aL to rs.

"ltcli'Ii cal I er t. ionl

7 1. D~est rat. i I cIit ioil May liegir1 iltl hen IJ1 inc i iIi ( V( I i lt. l Oil 15S

I iIt I Led . MlecliaiicIl(I des tratLi Iitca t i on Ii I t t -- oId , tI ox I c. liVio I Iiii1ie t I

\ijt tr t"Lo t lie stif r tI ac, ill i xi r ig i t wi Ii ItheII,%,. ariier , ox\'geimLted , ep IIItt

iet i c i,a.t, er. Thle new vqp 1 i b1 1) iii ui depthI I orI oxygen til tdLhe ite L' o XV-

gerlt. i Oil dependlls onl th ta ,Ipatc i t v ol t he tnecliri i cal I ci rtil a t oi , x- e

sillippiI v rIt e , a tiiul t-t e ohI oxygen deia nd )f- L lie rest, iwo i r- At oh i) he_ (-

coirpos i t in o orIgarl1i c mla t t er ;ii id th lt hei I I atnd/ or11 bio I ogi al) ox I (h-

Li in il 0trillilcell otstL i t iienits biegi it in1 the aera tell wa tet t o I1 uwn1. ILaV i IIg

,an i so Lhe(-rit I reae ra ti'd wa tevr coi I rimn tiietrts t ha t eqiti I i b)r i 1111 con Stt )LS

a [id a ct i v i t y toe(- I i c i en11t s (10 riot rei ire-( t eiipe rat titre coir-rec t OilM 1 illti

elpII Ii I Ihr i urn modelI (1 rig I e et a I . 1980).

flypo I i nimet itc at, rat Li onl

72. Oix i datL i onl p rtces se s arlid aerob ic decoinlpos i t i oil of o rgal it1

ti.iIt. tevr m 1it i a I Ily ticciii- oil y inI ae rdat ei lypolI itrinetL itc water I-. Thie tetrtpet-ra-

tilte of the hypoiiniiori iiicreases approximaite lv toi 0.01-. 10 C alioVe

40)

normal as it is partially mixed with the thermocline. Occasionally,

metalimnetic oxygen levels are unstable during aeration. A zone of low

dissolved oxygen or even anoxic couditions may occur near tile metalim-

nion. The level of the metalimnion also drops as water is transferred

from the hypolimnion to the metalimnion and epilimnion.

InterrelationsisAmong Reduced Chemicals as theAnoxic Water Column Is Aerated

73. Different phases in RE-AERS are based on (a) the pil range

over which the phase is functional, (b) the DO concentration, (c) a

stunmary of the sequences of major events, (d) diagrams (see Figures 11

and 12) which depict the major chemical components and interactions,

(e) a tabulation of the processes represented by each of the arrows in

the diagrams, and (f) a list of algorithms which summarize the various

processes operative on each component shown in the diagrams. The boxes

surrounding each component indicate whether that component is barely

detectable (dashed line), increases in concentration (double lines), or

is in relative equilibrium (single line).

Initial conditions: Anoxichypolimnion before aeration

74. The pH range over which the phase is functional is 6.6 to

7.4; the Eh is approximately +50 mV or below; the DO concentration in

water is 0 mg/L.

75. SynpLsis of initial conditions. In an anoxic hypolimnion,

the redox potential has dropped to approximately +50 mV or lower during

the course of stratification. Nitrate was totally exhausted followed by

accumulation of dissolved ammonium and manganese (I1) in hypolimnetic

waters. Iron was then actively reduced and accumulated in hypolimneti(

waters, as did inorganic phosphates that were released when ferrous iron

was reduced. Sulfide can then be released from highly reduced sediments

where it may react with ferrous iron in the water column and form highly

insoluble ferrous sulfide. Sulfate can also be transported into the

hypolimnion via inflowing water, or be produced by the decomposition of

41

IMPORTS

COMPONENTN CODIIO

C142

EEXPORTS

sulfate associated with organic matter; this sulfate can then he redilced

to sulfide which can also react with soluble ferrous iron to form in-

soluble ferrous sulfide. Anaerobic microorganisms then can use carbon

dioxide to form methane. In hypolimnetic waters, ammonium, soluble re-

duced manganese, ferrous iron, and phosphate continue to be accumulated,

as their presence in the tailwaters of projects with hypolimnetic with-

drawals indicates. Suspended ferrous sulfide may also be present.

76. Summary of processes. Figure 11 presents the components and

pathways of importance for anaerobic conditions in the hypolimnion.

Arrows in Figure 11 are explained below:

ArrowNo. Processes Represented by Arrow

I Import of dissolved carbon dioxide (as HCO3 )

2 Diffusion of dissolved CO2 (HCO3 ) from sediment

3 Export of dissolved CO2 with outflows

4 Reduction of CO to CH2 4

5 Release of methane to the water layer from sediment inunderlying anoxic water layer

6 Export of methane from system, primarily as risingbubbles of gas

/ Import of ammonium with inflow

8 Diffusion of ammonium from sediment, interstitial water oranoxic water layer beneath the water layer of concerninto overlying water

9 Immobilization of ammonium

10 Export of ammonium in outflows

11 Import of reduced iron with inflow

12 Diffusion of dissolved reduced (mostly chelated) iron

(Continued)

43

ArrowNo.. Pro.'ss's Re'prtselitt'd bv Arrow

13 Precipi tat ion ofI fevirrous iroil roi1 water laye r (f cicerilto sediment

14 Export of dissolved reduced iron ill mttlo%,s

15 Re lease of di sso I ved in norganic" pIospha t e Iroil) sedi mentinterst it ial water into water layers of concern (twomajor imecianisins lor producinig dissolved ilorgallic P0are, desorp .t ion of occ lutded alld ll llocc I ulled iflorgjlic 4

l'o( 3 f rom sediment and mineral izat ion of organic Po 3 t o4 '4

inorgailii Po 4 ill sediments)

It) Export o1 d i ssol ved i norgaiit i c phospiate wit h out I lows

17 1) i I his i on )1 redticef Iialig. ii'se roiii st'f iiiiellt i iit A t e rLaver of 'Oci cii('

18 Export of dissolve d ilte 1aligalle.,s;C witli olJtlow s

9 Import of di sso I ved rediced iiiaiigaiese wit Ii i ni I ows

50 Release of inorganic s ul fate from aiiaerohi cal lvdecompos iitg orgiii c siu I tate

21 Di if us io o dissol ved i oiii ag.ii i c sill late into sediientor WnderIvi rig ariox i c water I avers

22 I)i flIs ion of d i ssolved i inorgani i c siul fide from sed illneitor nilderlying aloXic water layer

23 Redlict ion si1 late to suit ide

24 Export of dissolved sulfide with outflows and advect io

25 Precipitation of dissolved silt ide to sediment or uider-lying anoxic water layer as a conse(fquenice of theformation of insoluble terrons sulf ide

26 Export of dissolved inorganic suiltate in out { os

27 Import of dissolved inorganic sultate with inflows

28 Export of dissolved and particulato organic matterand sediment (suspended) with out flows

(Cont inued)

44

- - . ---.

ArrowNo. Processes Represented by Arrow--,-

29 Import of' dissolved and particulate organic matter andsettling the suspended solid into the sediment-watersystem

30 Interchange of dissolved organic matter between sedi-ment and interstitial water

77. Algorithms summarizing the various processes operative on

each component in Figure 11 are given below:

Factors Influencing ChangeComipnent -of Concentration of ComponentLs

D i ss olIve-d

do02 bit =0. DO concentration =(0 mg/I.

dNH + /dt = Inflows + Re lease from Sed iment or Underl1yinugWater Layer + Ainioni ficat ion - Out flows-,' - Nil4(Biological Uptake + Di ffuision into OverlyingLayer)

dINO /dt =0. NO,, concent rat ion =0 mg/ L

dNO 3 /dt -0. NO 3concentration =0 nig L,

dDOM/dt z Inflows + Sediment Release + DOM (Part icuJ ate, OrganicMatter (POM) Decay) - Outf-lows - DOM (DissolvedOrganic Matter Decay)

dt:0 2 b it =In flows + CO 2 (D if fus ion from Unide r lying Sedimentor Water Layer + Dissolved Organic Mat ter Decay+ Part icul ate Organic Matter D~ecay) - Outt l ows

-CO. (Carbonate Format ion + I f fUS i0n toOverfying Water Layer)

dPI)4 / dt in flows t PO4 ' (Dissolved Organ ic 110- l1 ecay

+Particulate Organic P4'Decay + Biologicail

PO 3 Release) - Outf-lows - PO 3 (Format ion4 43

of Part iculatecs + Biological P04 Uptake) +-34

D~esorpt ion of P0 from Part i culate Matter

(Coll tinue-d)

Present InI oitf flows.

45

Factors Influencing ChangeComponent of Concentration of Components

Dissolved (Continued)

dSOL 2l/dt I tlows + SO - 2 I)issolved Organic Sulfate Decay +4 '4

Particulate O,'ganic Sn ltate Decay) - OutIlows -

S)_ (Biological Uptake) - Sulfate Reduct iou4

dn /dt = It I ows MNI+ 2 1 D if fusi on from Sed iment s or Anox iWater Layers + Dissolved Organic Matter Decay +Particuilate Organtic Matter Decay + Reduction ol

+4N11t ii Suispenided Part i cu iate t'it t r) - Outtf-Iows"

Nri (Biological IIpt ake + 1) itst on to Over lvi ItgWater' + Formait ioII of I soluI)e Pre c ipi tites)

dti' F /,It I nt I ows + Fe I) f t its iot from Sediment or Antoxi cw ,ctr livers + Dissolved Orgautic Natter l)ecav +Pat irti lIate Ot'ganltic Natter l)ecay + Reductiont of

Ft it Suspertded Particulate/Co11oida Inorganic

M.atter) - Outllows"'N - Fv + 2 (Biological Uptake +)itusiot to O)verlying Wate'r Lave'r + Formation ot

Insoluble Precipitates (S 2))

dS 2/.It S 2 (1)i fus ion from Se d imetI 01 A1iox i c \ter Lavers +

Dissolved Org.ini( hatter Decay":"' + S04 So Redic t in)

O- t flows' - S (Biological Uptake + 1)1 flitt;on toOver lvi ng Water Layer + Format i o of I Inso I t) I e1 rec 1 i taLes )

d(CH4 /dt l4 (1i Itis ion I rom Sediment or Aiox ic WatrI layert's

+ CII 4 (eltantogenteses) - Outflows" CIt,- (C1)11it-

siot to Overlying Water Layer)

Part i ct late

dPOl/t t nflows + PON (Sett liing froml Overlyin g Water iv er)

- Out tI ows., - PON (Part i'ilate Organic Nattter l)Detv+ Sett I ing to Underl ying Water or Sediment l,i'vet')

(CoIt i etd )

Present in oit I ows. w

Sul thydlryl groups that call he released as S or S, butc'onit i I hei oxidized il lte ii lack ot 0,.

4o.

Fa cto rs I II fILIDCI In i ~ Ig CngeCoppnent ___ of Conceit ration uf Comporieit 5

Part iculate (Cont irmed)

(IPIM/dt Inflows iPIN (Settling from Overlying Water La1yer)- Out flows; - PIM (Set tli ng to U~nderl ying Wajteror Sediment Laver + Part iculate Inorganic Mat ter(PIN) Decomposition)

Present in outflows.

Ae rat -ion

78. Hypol imnetic water under init ialI condi t ions subjectedl to

aerat ion should ma inta in a pH range of 6. 3 to 7. 5, an Eli above + 400 []1%'

andl a 1)0 concent rat ion of approximate ly 5-6 mg/I. or more. 'o rnra t on ofi (

ani oxidized layer on the sediment surface indicates the (omplet ion of

aerobic mixing.

71). SynoLPk's of aeration. Mechanical ci rculatioll of the Water

column d istuorbs the reservoir and] ma inta ins a uniform dissolved oxygen

content tin the overlying water (approximately 5-6 nlig/V) throughout the

des trat itied rese rvo ir . The uipper sediment Ilaye r becomes oxid ized when

aeratedl water reaches the bottom layer of water. The sediment be low the

t hini ox i d zed layer remairns anox icr. D I f fins i on ofI redluced cons t It lien t s

I rom a nox I c sed Oi ent s t o t he ove rlIy i rig wa t er th[Irough t he ox Iidi zed

s irtfI c Ial sed Imen ts i s mi n imalI.

80. Oxidat ion react ions of reduced chemi calIs beg in soon atter

aeration of the hypol innion. Format ion of oxidized chemical forms is

soon l iiited by dep let ion of the renmain inrg reduced chemli c I s . P rolio t s

of ox i dat i on rema i n i rig illt the water a re subject t o f t! t( hr react I is

Some sol uble f orm of ox id ized product s, such,[ as No, I w,. I I (d it I use, anid

i nteract w ith h igh ly reduced sed iment and undergo den-i i t r if I ca. I (1oi

and/o r rednict i on v ia mi c rot) ia I ass imi Ilat in w it It a poss iff he net l oss of

nitrogen.

81 . S imulI tanieous itIi tr i f ica t i on Iin t he aeratedi hypolI imiIon rajpidly1

replen ishes any itIi t rate l ost by (it f its ion or I I usli i ng. til the (4 her

hand , even when inorganic phbospha te I-s added to 0 re servoir by ntIw

47

--ob .. --:- * -i-i-- ___ _

t tilt1 lick aitse o) f 1 rt c I t 'I tt Ii ii n r cotp rer c~ it t I t oil , lila 1 ii v WI t. I Fe

I It ittI .kk 111111)1 lit te s d I sSi I veil s I. 1 lat t I I tIWs 11 , oI I iS ',[ll Idt I

ItIel eaeld Iv o rgiz11 llt t teIr , on aIs F tS tint s 11r faIt, sr'dIIncitit I s "xIiiI.

1.~ ur 11[)M dI ox Ide a tlii lI .[I 1. Li on re s il t s Ilia I in Iv li t Id toiiptis I t Ienr I f ig.11

ii1i t li it II I[I it II, l xId Rtt Iil oilirigir I , t- i rtlegs iii 1 % tXIol I li i1 .ii lit] tss ll

si i I t t tjlit - hi t c ,i nItIi IkI lilta t( i1 [1itts ( Ir L lt h ti tlis I

ci Ir e Int itr j I( is d ti x I (it' e t I r, t1r li sp ait it- i tll i lrk11 I It c )t tii

t lit -stt I in t L ir i mls Co cl tr I i li es o I I nI li I ve t Iilt Ii t e I l IiL Iit I

StI IrIts I IiL tt o r ltriitaL ra ic ILitra L e Ihite (ar, tt li i tiiitwi, xi ,

Llic h po t It II s I l Ie s xyit l ) iti iii . If%,(; et ysi I 1ilt ) ti ' s i late is p raI t X.1t1

oit ox i I d I ed ei .1. g int se ci ae I te'i 11 te rsc a 1)11 .

. 82. -,(II Id Is 11 ciioiiiio iv it iriteeI;es o F igtire 1 c ltt t Is t N hr dtiltnn I " I ni

' 'g( I s I It rt S 2 l t orl t. Ili l t I ox ,II ea I li lls .S Arr 11c 1c I IIsc it r gt hCI I

ire ,(, t o I t nei lt I xId i -~ ,C ' 1 I' L0 SI 1tC 1-1 ItII1

N,1oIogIc %.ltldIate 1 rotLedses te(iIsit et i :Ftl

82. Su i leiue% i t - o e i s i t, vs. - t t n (12 1) N-1 i , Nil('1lt. il

p- t Im~v I i st iant -rttlithe o f iti il i ilt tos i. A I ro% sI ri it VrI ti rc ri2

2. I Iii(111 1 Ie en fo triIiii o l i ) N

3 e(Iu rme t o sk II d o iLi48oi

0,~__ _ re( -Irm nt frm tJeoxia

P 3 ANOXIC WATER 39 DOM F04 AND AND DO

COMPONIMNT CODIIO

-~ ~ ~ ~ C IN REAIEEQIIRU

Figir 2 N~rchI~c hagsan atwy as"T ts

w St th ( MIst 2a 1 ain proli n nx yoIii

4e9 2N H

- -- - ~ ~ -- cc

ArrwNo. 'r, ,t.ssrs Reerosorited by A ,ow,

8 Pth tosyilti ht's Is v' I I gai III sod llieln it

) ) Its I oil oif kI i oll' d Io It do I r ui sed tlerit i nto '.1 ter I IYk, r(it (" )l|[ '1 "1r

IO Export of tIIso Itlved kto' i -ol j xi s 1 1aI1 w It (il L I o .

I I Ilipo. r t .110 lllOliI 1 '.41 i i iit It0ms

12 Import ot itrate and Ii:tri tt' itt lilt lo,.

13 1)it tiS i ( of illri le Ii /t, 1 I,' liil itm l 11 un I m I - iiin rl t to L t itt r

I aver of (nre rII

14 N i iluno[ i I i za t ion an t i i \tt iiin

15 Nitri ficat ion

lb N it rate redutt ion

17 Export of nIt rte r rid Init tt with oitt lows

1 Sa Rele'ase oI redtn', ed ! 1s vI ,'r I roll I roln a[Iox c sed i llmerit t oov' r lv i r w,,tg r to I imi

18b Prec ip tat I o i t otedti ci i.rol to So ,i mollrit aiS j coIseqoe 1 1er

of organi and i riorgaii colmpltxat ion

19 ]lomoge'neet ic ,1n( hotterogtnot lc o x i dat iol oI terrous i ro toferric i rol

20 Export o fe rr ic iron with otl t ws

21 Colloidal growth of ttrri c i roit ll l owd by iIsorpt ion and/orsett lernent onto s edjimtt as Fet)l )I ft

22 Release of dii ssolveil redncet malgarin eoa ,, -;, I rom anot srei i lle 11tto overlying water column

23 Precipitation of reduced manganiese (n i t o st iri'lilt as aconsequence of o rgari i a nd i no rg n c comp I ox, t i oil

24 Import of dissolved organic part iculate matter arid set t I ljgof the suspended solids into the sediment-wato'r system

(Cont inued)

50

II

A r rowNo. Processes Represented by Arrow

25 Oxidation of manganous manganese

+426 Export of manganese (Mn ) with outtlows

27 Colloidal growth of manganese ollowed by :,s, rption anid/orsettlement onto sediment as MnOotl

28 Import ot manganese with inf lows

2 ' Import ot dissolved phosphate witi inilo 's

30 F) rm it i on ,,t iron (Ierric) phosphate (ppt)

31 Exltort ot diss(lved phosphate with outflows

32 DiituIs ion of dissolved inorganic sulfide out of sediment

33 Oxidation of sulfide to sulfate

34 Import of dissolved inorganic sulfate with inflows

35 Export of dissolved inorganic sult.,te with outflows

36 Import of suspended inorganic and organic ferric compounds

with inflows

17 Import of soluble reduced terrous iron with inflows.2

i8 Import of soluble reduced Mn wi tth i ni lows

39 Interchange of dissolved organic matter between sediment and

interstitial water

83. Algorithms summari-ing the various processes operative on

each component in Figure 11 are given below.

Factors Influencing ChangeComponent of Concentration of Component s

dDO/dt = Inflows + Aeration rate - Outflow - DO (Nitrifica-

tion + DON Decay + Particulate ON decay + Sulfatee+2

Formation + Nethane Oxidation + Fe Oxidation

+ Nn+ 2 Oxidation + BOD + Sediment Organic

Decay)

(Continued)

5i

-- -- ______ 1

.i . t t- lit I1011 i.ig C h I

t pol I( It'n o t (oilO lt rat i o1l (td tlUllpoltllL S

INtI idt tnflokw-, + I)i tuiion troml Sediment or Adiaoctnt k-iter

Livers + Aiionitication - Nil, (tilIvers iol ,I Nil

t o Nit r ite or N it rate + ) 1 ant L'pt,,kt + 1) i I tu f lii

++

-+Nil fixed onf C: ki Minci t5)

d . ±No +N ')/itt lilt l, s + Ni t r iI i c,ti t o - )n t I t l s = NI N it. rit c

Redlict iioi + Plnt Lptike + Di I tisi iim t o Ad iit nttI.' e r Live U si ')1 S di ille t s)

dDOlN tdt li I I ows + Sed i ment Ret ease + tON (P' rt iu I ite() rgai i o Mat t r Decay) - ()1ttL I m, s - tIN (It)'I D e ,j V+ 1) re i p i at i on a d (:(lm I exit i oil t i t t a It ht )

(tWt., (ift = tnt t o s + 'O ) (t) t ilus ioln t r-11 Su ti iieit t ()r AIicit'It-l L t, r LIvor s t 0Irgali i C NAt. toi 1)ov + h'Itlill

x i (tit ion) - ()It Itows - CO> (t)i I (is ioi i Lo

Adj nt ater ltyers + CarholitO toUrnil,itioll +

Bio I) ogi cti I pt ake)

dtil, (it Cli (1)i [lus ion t roin UInderl y i ng Anox i c Sed l ltnt o r

WLitIr) + 'tLttltlog lles is Out fl Iows - tl, (lxi(L]-.4

off)l + DIlIns i )n to0 Adlj a con t Wjt cr .,avt~l o r

Sed i mnit )

1) i ssolt I d

+2+)(Fe+ iI i tlnls + Fe (1)i tlius i oil trom Adi.i cent Alox i

Water Layers aid Sedimlent + tlrOgailic Natter It)o-a)

- t1o+ 2 (Oxidati ion o Fe+ 2 + Forlation of

I tisolldd)e Complex + Riolog/cil 2 ttakc - Mtl ,,05

leF3/dt lilt lows + Fe (Oxiidat i oil o t e+2 + 1) i I t iio n I r111?Adiacent Aerated Water Layers + Organic Matter

Decay) - Out Ilows - Fe - ( lor la t i of1 o t Iliso 111) 1 cColp I exes + Set LI i fig to tinder t vi ng Water L.iyersor Seili mnt)

dMi+2 /dt t ift ows + l11+ 2 ( t) i t his i1 i tromi Aij aif I Anox it

Water layers or Sedi imetI + Orar1ic Mat tor t)o.v)I

Out flows - Mil +2 (iot ogi cat IUptake + 1)i ftlls im toAdj a ce nt Water Layers or Sed i ment + lxi la ti tl to

Continied

52

I tI sS ' I hu i I fl Iht/.)

d~~~~~il~ ~ ~ + tM+4F ili ts I ut t\1) t in10 jli tlt

Co [It L Org.an I Compj I xc

+1-4 + I'

(I M; /dt l ilt I o.5 + .,III (IX.x~ I I un t '111 t I t 11s 1i 1

Ad.1 t et [At,~~ I i iig k~ Wt i l vt, l lt

Gr owt h)'

-iP /tt 1iii l ows + PO) 4 Org'iui ofI 1.t t c~ I t(Iv + 't I Ii

t roiii Sed itutuit or Slispendiltul !'It iIt c I li I .11

R t eaIse o fI( 7) - lit f lo"s - I tI.oIil., t~ 'II

I iso In ti I t' Pt I L' 1 11 1 L t t's w i If I k i

Ip t a kt,

(isu /ut I it tIuu.ws + S 1)i I tus Iit I tti Audj iit it Aiox I t h-

menL Or- WaIter I- \tV'I-, + At,0'rtlL UrIgAnil .'I t t,

De, - (ll l Ioos S (SlIlt I d t ) I xit.utu L 1

thiuI~u')uj 4 '4 J It + I( I t tus l t to Ad Ijk tit ksI t tvi trS + It I 1.1t tt 'loI I iisoI iitI cPt~ Iuu t Itut t

(ISO,- ',It I hif loI + SO1 (Atr, ti k lrgoiiu1 NI t t c I}* \!' 1 +

lixiui lut a I ultt I Sit I I dc 1 its Iin I tI )Ili A I Iuit 1).

Ac rit eu Wil t r.i Lvers)I - Oiltl Iows, So 2i ( 1) 1titI onu

t o Adj i(ctit )a ti i i I Si)-2 I I o~gi I (.11 p-

t i k + Fo rti Lt fo f u Iis,()ullle P'ro ijuI tit es

I'i it 1 iitoi a t

d POM I /Lt lilt I oss + PW)I (So t t I I ntg 1 roiw ( ive r Ii yt1i1g Vl t r y ce I

+ I Iiiiihuti I I /u"t i on ) - Out1 ltws - Pt iiN( IhigmnI

Nal t h-r D~e c .1 Set tlIIig t o tinde r I vtIofg W. It r I I %'I

o)r Setl i hut't

II' 1 M/(It lI [t I o %. S + 1, 1 Mi ( Sett I I I fig i v t vll Me tl ig Wiat er lv+ iuu ri it i on I I ist) I iltI It, (?ottI exts, ) - (ilt t I (((s- P) I M ( Se t t I I ig t ol liu t I- i if ig Wi&' I t t - 1ivc I orISeull I Illentt + Dl, iitpos I t Io Cut I

PART IV: EVALUATION OF RELEVANT RATE DATA

84. There is only limited information available regarding aerobic

processes in man-made impoundments. However, there is considerable

information on natural destratification in freshwater lake systems. The

range of data for various aerobic processes is shown in Table 2. These

processes are site specific; values for nonreservoir systems are in-

cluded only if data for particular processes in reservoirs are not

available. All of the information shown in Table 2 is expressed in

terms of grams or milligrams of the component being released or de-

pleted per square meter of sediment surface per (lay.

85. Oxidation of reduced chemic,:'s in reservoirs is highly tem-

perature dependent. In reservoir hypolimnia in the Unitet States,

temperatures typically range from 50 to 15'C. Some I aboratorv st ldle"s

cited in Fable 2 tended to use large amounts of the particulir substrate

or were conducted at higher temperatures and may have vil el ab,1ove-

normal rates. Inflow and outflow rates depend primarilv on a rtes'r-

voir's hydraulic budget and are not considered iii tiis stltidy. Slike

almost all aerobic chemical transformatio rates are sitte spect f , the

flux rates in Table 2 reflect the range of coictent rit til ns aI robi(

products that may occur in aerated reservoirs. Estitated rt leaise rates

are not shown. These rates must be furnished when using the RE-AERS

aerobic conceptual subroutine hased on this description , which simulIates

aerobic processes. RE-AERS is described in Part 111 ot this report.

86. Sediment-water reaction chambers are currently being used in

the WES laboratory to provide the rate data required by RE-AERS. ipon

completion of the study of which this report is a part, data will be

provided in an Engineering Technical letter (ETL), available from WES,

in the form of fluxes (i.e., net rate and direct on of release) or

tirst-order coefficients, or in other forms. The ETI, will also provide

information on user methods for obtaining data required tor RE-AERS.

Table .1 presents a preliminary guide to these methods.

54

PART' V: LABORATORY AND) F IELD S I!) IF

Materials anti Methods

Characteristics and

87. Sediments from existinug CE reservoi rs arnd sorils t rol) propose!

CE rese rvo irs we re samplIed t o fet erir intit t lie e tf c(t s o f oxygera t i on ()[

nutrient and metal transformation rates and react ion proceVsses. So i I

and sedient samples from tie( I ol low inrg rese rvo irs were used:

CE Reservoir Locat ion (CE lDistrlkct

Fau Ga IIe Rese rvo ir St . Paul D~istrict Mini.

Browns Lake WES, Miss.

Beech Fork Reservoi r Hunt ington D~ist rict , W. Vo.

Eagle Lake Vicksburrg District , Miss.

Ri chard B. Russo I I Rese rvo ir Savannah D)i st rict , Ga.

DeGray Reservoir Vicksburg l)is.-tric-t, Ark.

Bloomington Reservoir Baltimore District , Md .

Red Rock Reservoir Rock I s l and 1) ist r i c t , Ill

Greers Ferry Reservoi r Littlet Rock D~i st i t , Ark.

88. Samples fromt proposed rese rvo i r s i t es were co I ec tel anid

hanrd led ats descr i bed by Gunini son e t a I . ( 1979) . C'omp~os it edi sed r ment

samplIes represent inrg var iouis so il types in each rese rvoir were mi xed

thoroughly. Laboratory and field experiments were carried out to

eva Iluaite the inute raction of sediment or newly t Ioodedi soril w i th the

overlying water during dest rat ificatioli or reaerat iorw

Laboratory Studies

89. Large-scale model . A react ion chamber was const ructed ot

p)Iexiglas in the form of at rectangular tank wi th d irrenrsions of 46 tm

long by 46 cm wide by 121 cm high (Figure 13) . The chamber and labora-

t tiry experiments were ha sed on the methods des cr ibed 1wv Gunin i son anid

Brannion (1981) Several modi I icat ionis described in the fo! lowinrg

WATER QUALITY MONITORINGINSTRUMENTATION

WATER-'

" -SAMPLING1-/ -. PORTS

'-CIRCULATION . 'SYSTEM "

SEDIMENT -

OVERFLOW AND GAS TRAPPING SYSTEM->

I lIIIre I s I +(ll]It'll t ,,] t 't, e'•l ct o r tlo+

r s" , t 'ilit'le I'o I ( k o,(lld I t It)If" II i 'f S( rvo 1 1-,

t(. I l )il n.il l.li , t l Lhe If t',j( t I ( t I~ llllhc r" to , I lllIH 1 . L (I t, s tL r.i i i It i i

r fI t - 1-. 1 1 fl I o fi d t I [ I s l .

IM ). I Jl -! , ,aI t, nll,,, lhis .sy. tem u.sed 17- hy\ 92-~(m ]polve(th-

Il l . L I, ,ll l t , I I'l \'. t h %-t ,r ( 1 1111 l g (. [1.. iI1(' p h I, III.)] .' t, '( tI1

,odc l

I d I I w I~ r:lvsV (111 ll.( th I , I I V ll'ilIIl lt , 1 ,Il o st(( d i I I It II (

,il f g I ig I. 11t r, t 1() I u fi t o te .ic s snh ll]-tIt '- ough l~i ' ,11 I "t t' d I t ,l ,I.-,

,,:<y * i x , m I ', 0 IIh t , t lit, d l It , -%-t r 1t C I 1 .(, c, , , tI I I

k([,I ()t d. b hl'.1 b I ,I (l l I I r ,t 1 - h i' w' , I t c I t h II m'n . t sv.std ' , ,i l h il , I1,I I ',

t I(, It l it , p I, x 111'1t c I " I ll Il , 1 ) t, ,r ye ,ge( .itx klh ,,\ ' l 1 1 t I, I I

W t 'I C II 11 t l I lt IC.II I I( ol llfl~ d /7 t 0 . I ng I .I o 11111 1 1 ('I [ I I t eI I z d I.

(). I ' . ' .I HI I ,II, h au liv rs 'I'e s , , I i " VI I " .') [ , I t Im III ( , ,r I li . I ,I

t t 1 111 1 1 t I(' I V Ifig 'A t 1('( Jll(' 1 ll )X )v I II Ig k I

were i niiihatIet t-o r 4 to 6 mont hsun (rItt r ariaero b it L'( ndo i oris .A IL' r t fit,

anox ic water was sampled, a gais exhaust port was opened onl thle top covc'

.1nd ae rat ion was begun. Inrcubiat ion p roceedled at a cons tan t tetmjrt r Lr

of 20'C inl the dark.

Ini Situl Study

93. Ani ili situ ii i bfit ion expet'r imfent was conducit ed iii summer 1981I

to dtr't'iiit' thet oxi dat ion rate of- ferrous i ron (Fe (11) ) anid miiganoiis

man11ganlese (Mni 11I) inl the hypo Iiini on of Eatn GallIe Rest rVo ir at depthus oft

0. S arid 9.5 il. Tlwo-huridred-anl- lifty ii of- sti i'f-'Itr serfiiiieiit s, to I l'ct ed

w'ith inl Eckman dfredge , wert' mixedr anld added' to I -1, if'iitiiotfi jil .sti

ho()t t le s wfi i cl1i we re' L Iien I i I I ed w fi 11(o4 t 0111 la ke wat t, rs . lTV'iiH i o f s o lI1i -

ion coutjainiirg reduced forms of it-oril arid man11ganlese Were addehd to o'.itl

hot t I c . B~ot t I t's wt' re' t he'ni re t ii rrir(I to0 t lit' hot tor o110f the l ake t o r I

24-hoir incuba t ion per i od. lT'e tempt'ratuire' was 22.5 antI 14. 1 O(, ainI

ofiss o I ved oxygen was 4. 3 ainii ) ig/f. iii wate'rs iist above thet sed imrenits

for thIe 0).5- arid 9.5-n s it es , respec't i ye I V. 'Fli' wa Lt'r saiip I ('s we re

t'o I Ir'tr'td .is tftstr i hr'd he l ow .

S;iillp It ec o I I t'ct 011lan

p) rr'srva t i oil inI iho ra t o iv

94. Ariox itc wa t er anid sr't i milt sail Iles Wer re' i ri it i a I lI sairly I i'd iii)

iiit rogeri .itiliosplit to imairntainr their r'ariairohi c integri tv. Pairt i ciiitt'

.1iI di sso lvr'd forms of tlt' chermicalIs were' separated by f ilIterinrg thlrouigh

ai ). 45-pml mneilib rare FilIt er. So I iihle, reduced ri(t a Is (Fr' arnd M11) wi' it

fItte'red tfr rtigt ai rrrrmh r~iri f i I ter of pore size 0). 1 pil ( Kt'rrirdv et .11.

19714).

9)5) S, ip i )'vs f or p)a rt i c ii l atLe ant 5(1 i ds I t' runt r i ei t s we'r' p 1 rt'sst r vec

iirmef liti' Iy byv freezing at -40'C. MetalI samples were preserve'd by

ic ifi icit ion to 11[ ' 2 with concentrated lICd or liNt)1

96 . I nit vers t itL i a I wa t e'r wa s sepa ra ted f roi sed i mernit by cent r i -

trig i rig .i po rt i onl o f t he serf inmen t a t 10 ,000 rpm ( 16, 300) x g) fo r I16 iii i n.

Sid i inruit wais t heir a i r d r i cr1 andl ground t o pass ain 80-rueshl ASTM s c ret'r

Tlhe drrir'r sed imen t sarfp In's were' stIored iin t i glut Ily cai~p('t hot t I 's a t

anuhi vnt t empe ra t ure unt i I c'lenni calI ara Ilvs is.

57

C-hemi ca 1-_ A rialyse s

97. Water. 'rotal kjeldahil nitrogen and total phosptortis werc

converted to amnionium and inorganic phosphate by digesting water saiples

ott a semiautomatic digestion block (Batllinger 1979). Various toriis o

inorganic nitrogen and phosphate were detertiied with a Technicott Auto-

analyzer It in accordance with pr,,cedures recommended by thel U. S.

Environunental Protection Agency (Ballinger 1979).

98. Total carbon and inorganic carbon, including soluble and

particulate forms, were determined with a Beckman carbon ainalyzer (model

915 A) equipped with an intra-red detector. Sulate concentratiois werc

determined by the turhidimetric mnethod (APIIA 1980). Iron and imangainese

concentrations were determined with a Spectrote trics Spectraspan II

Ecelle Grating Argon Plasma Emission spectrophotonieter.

99. Soil and sedient. Exchangeable nutrients and metals were

determined by extractinig moist sediment salmples (the residues followitg

centritugation to retnove interstitial water) with a series of extracting

solutions (Gunnison and Brannon 1981). Analytical methods for chemi -

cally extracted solutions were similar to tIose tsed for water Samples

(Table 3).

100. Total organic carbon iii soil or sediment was determined

directly by combusting air-dried samples at 550'C for 5 hours in a

muffle furnace (Davis 1974). Carbon content was then calculated accord-

ing to the equation of Allison and Moodie (1905). Inorganic carbon was

determined by measuring the decrease in sediment weight resulting front

CO2 loss, by treating sediment with 3 M HCI (Allison and Moodie 1905).

Measurement of physical parameters

101. Dissolved oxygen was measured with the Azide modi t icat ion

of the Winkler method (APIA 1980), or was estimated by using art oxygen

,neter (Yellow Springs Instruments (YSI) model 54) equipped with an

oxygen/temperature probe. Specific condlictivi ty (corrected to 25°t7) was

measured with a mho meter using a YSI model 3403 conductivity clI.

Water and sediment pH were measured by the glass combination elect rode.

Redox electrodes were constructed and calibrated followinrg ti proce -

dures described by Graetz et al. (1973). A specitic ion meter (ievkmnan

58

model S-113) Was uISed for Ehi arid pH ri'aSnrt'lenct s

102. [rhe temperature prof iIc, di Is [vei I(doxygenl, pHt, aind Coridut

t ivitLy in E aui Gal 11e Reservo irI se Iimeuit s used Iin the inl situ1 study were

measured with a Hydro tab Irarismi L tt-r P'robe (Hydrotab Corporatlonl).

N s 111lt s

S ed i mentit anIid So i I lr op e rt I es

1031. Proper t it's of t tie sediii~erits arid sotI s are, shown Ili [able 4.

Coinpos i ted saflples f roil) thc Ri chiard B. kiissel 1 Reservoi r s Ite tcrte col1

l ec tevd t r o IlI) II t, I-e r(rt -eI itaIt ive a IIt easI of th p )r op1)o setd I re ser -v o I .- SoilI

SAimlp Ies t rom ttie Ri tal ri B. kiisse I I s itte rte re [at ivt-lv hiighi II i t alI

anid con ta I ued appiet 1iafil,1- iiilnts t o rgan) i mla t ter,1. Itex tu l f lajs s Ift -

(cit I i of tile sol s '111d i ii-rt .iigedtvl f ro sanlity loamil (Faiil ;. Iev) t o

si It tv clayIv toa in( bt t Ioi I AlI setiiiieecit arid soilI s"iiiiles exi ejt toi

tthe [:,II tGa I I st-fiii-iiL (pit it '. 1) Iail a ileitijl 101 ,id corita ined ret-

alt I vtc'Iy I It tle orIga.. 1 iIoii1 arid 1,it I ogt-ri.

[issol1ved oxygten ( ii..t')it rai-Iins Ini thit overlylig %.It(ers1

[104. Cotll( crit rat I uis oft d i ssolI vcd oxvgeii Iii t he ove'rI fiug wa ter

of t fit z o i I -water reac tor chiamiber (1i1i 1 rig 111 rera loI ' it I nprI . i-t' shown

ili Table .Monitoring iridicate'd thiat .tissolvcl oxv.gct oiitt'iit 'if ttilt-

ove rlIy r ig watLer intc rea se] f rom an ave ra gc of1 4. I it o t, .i mg/I tohet %,, c 1

t he fi r-st arnd second day. Trhese va ILues wt,'re' t(iii i va It'i LtLo iii1 )xgt'lu

transfer capacity of 4.28 and 3.26 g 0 2/Ill ot setialcrit surfai' iu.

at 20C. D)is solved oxygcn content of the ov' r t i rig wi tin r tw11 Iu lit

orst ant th roughout the expe rimtent a fter I week oft at rat IM

Water and sediment charac-terist i(% dutrirr& ae-ration -stutdy

1051 . The pit of aerated water tended to ilicriva-tit1 fuig t ii' tcl -

t ilili study , but Changes ill pHi Were minor arid geritra I i v , i t hii I0. ') pih pi(

til I t . Be f o re a r r wd5s I nit induced i nit o theit rea (t i til ttuimte I , t tit, It'lox

piot enit I a I ( Ehi oit arioxi t wa tevr tin t he Beech Fo rk wi ter -- sed Iiiiierit sy st till

,Ir-rged + 14') ril% Redox piitent I a I o f t he wa ter r Ie reuIvased [ir1lilliit lv ' ittI

5~

er it i m t' +!A0 11\' ter r)hrla midi re a chvd' 4-f, 701 p\*' .' 1,,, 111.

mi titd at +6-50 m\' t titrea fttvr .Simri I ar Ell chaniges, ill the overly juig i.i tII

were noted Iin thle Eau a o IlIe Iw ter-sedt i it svstem at 20'C . eg, ItI Ieo

oht ae ra t i oin trea t mrent , sedh i irent Ell reg is tered hretweeri -200) t o-2 M( jijA

aid( reni)a I iied .ilox i c t Ifroiig Iioiit t i titlt I re ex pe r i irierit Chieri ct a

1qH71) )reported S imi I j ar t j uld i rigs t or other sed imlents anl ellnjdias I r

t ha t lest rat il-I cat i onl or other iiiealis o t aejrit i on I[Ii th tit, lv(I I r ig .,itI

Iid i [ot aff te ct sed imenit aijox ic corid It ils anywhiere but the th in oxi d I zt

zont, of sur f i c ia I sed iient . There was rio iid i cat ioil Of redox II v'. t rot

)O ISOiH i rig ( Ba 1v Varid lBeaiichaunup 19 -1 1 ) a s t lie( elIect rodes cooit I rmiir I I v

responided t o t he rnaeroh i c-aeroh i c t rea tint s . wi t e r conduct i vi t d e-

i-ea:1.sed once ae rat ionl begal I Iii t he Ri chiard B . Biisse I I wajtir-sed i uieiit

vsyteri, tol r eXimplllt t, -onidliCt ivitV d'leei ned trii2. 1 10) to

I S. 3 , I0 ()iirro/cIri Ill "I21"as.

C.Irbon -olit (nit ot

the overlviri': water

100. chmiiges i 1i 1rl 1- aid I ilorgai11ji c ji1 hoi cont elt s (0t lte

ove rlIi jig wa LtI- i iit se Ittih e C. rtsti\'o I rs duiju-r rig -iet, io arekllI showuri ii

Fi gui-es 14-20 . 1 if gent. rxi I jeacrob i 1 res p iit ionl )I ouar Ccoipouuits"

cciuih i t ioil% i i wt Ir -suIlei t juenuu'tsi gujiural I I itI rc 1 hgh k 111 ('it rIIt I

ot f r iorgarli c arid orgiri it caIrbonl, wt tcreas, ox Ik coildI t ins1' tenld t I dt, -

L'IVSVInoirg.i(I ic I arhorIc lve Is . Il I I tI fiui ry resii I ts i i itIi i cit c t liit

Ii i t i I coiiuet rt Itoils ofI o rgarIit .trboji weri Is o , 1 t lit' All, X Ik% ~Iu_O Iljj ,riwri L it vei-v I ow chaniges, oblsem t i i r fig t hue wjjOh ii t Lrcitniett

1(07. The (Ii sajppeairite rate oh i ssolIvet o rgiri I -iii rh is

s Iu it -i fit. rrs t wa ter-sehimenit Syst emrs oVer t he lIi it I 2 118 ,dLIvs '

at rob i c I nicujaL i oin . TotalI o rgaril jc (,;I rhori content n-L rioils r-eiin rued

consttilt or let- 1iried sIi gh tIy dnitr Injg ti Is I S IjitaI11t Io Of itrIoI'

108. 1 ri t he 1) rsenice o f oxygeni , 'eI ro i c hetierot roptis i1(t I ve I

nict iAm I i/f o rgall in. at t er iif wa t er arid sit I aIce sted mlerits . Softe( miet 11.it

ssprodticid i i the arioxi t svsteiri, however , .1 1 t trough t lte conuvers I i n .I It,

of Met hini1e to C0 I it tilie ox it( watt' - St.i rmerit svste lii hs iot Ni t benl di -

t i ri Ir niiu . It hiujhit a tirdn of t Irt (. irborj I rounl ox I (i zIt dIiit 11i11t %-.s

60i

77 Zn : z~

- -~

o a,

-

=

I IOHV

cc

z0

oz~

ca 0 > 40

wU 00r

< 0 L

TC T

1/6-r c -UV:

7 (

c aa

0 00 0 > " >

000

C

E- c

I L - - - A I

62c

-. ~ ~ ~ ~ ~ 4 --- ~- fl7kl - -

Ir /I

Cib r T kliaf

0I II 0c a,.I ~ I. ~ .

Lii 0 a

Tf T

00

40 R E3 RUSSELL RESERV.OIR

:30

F 0 AE -----------

40

30

X, ANAEROBIVFUCON

-.----- DISSOCLED INO ,ANMQ L,'C'.

0 4 1)

DlAYS

I-I iguIc 20. Ch.i 11ges if) orgll an11d inlo rgan11i c c'] I-onl om t (t s (Iht 1WoVerFI ling waJ teCIr11 in (A cA ii 1;. Russe I I Keste r'co ir unldo,

d 1001) 1 Mid~ A 11110~ 1-0 c( toli I tiol[Is

f (muid i mo rpo ra t 0(1 w it 11 organlIk-cl ta 11) in la kes ( Rudd et Ii I ' . ,

Zefidr mid1( Rrock ( 1980 ) report Id a l owe r riltev o I met h')ne ox dakht nI l i i

like sed i ilI

109. IThe d i sappea raiice rait es over1 3 %,eks o f (-, ro ll i i)i ,Irjoul

%-It e.T-stod I lenI t Svst ell]s unider atrob ic con d it i ons at -)0'( 1-( SI iomii li tlo

tal)Iiila jt 1 onl be Iow . Ca rbon ili Lte Wdt crs o t Fi g I l ,i ke a nd K i clih,i rd B;.

H usse I I Rese rvot i sy stemils tended t ( 11111 cc laI tev, wil IlIe tha,1t iin Beech Io I k

Reservot 0,I Browins Laike anid Ea al ,IIe ReserIvo Ir Ssst ems3) t enkd to

(103 I 1 lit,

0)4

CI.Hes, Ivt I i t rot I ~/r'/(ay xi

Beech Fo rk Ruse rvo i r I . 36 0) .1 i

Browns Like 0,54 0. 14

Eagle Like 223 -o1. I I

Ii LI ie Rese two i r 2.21 0i.14

R i cLiJi II h. RLISSC I1 IReservo I r 1 .50 -0 . P)

Ni t ro~t'r coircenit rat I ons in itwit ers

110. Nit r i fI cait Ion irppeaired t o be s I ow in Btfrow,,ns Like andl Red

Rojck Lake SedirnreIIL-w,-ter systems s ince stnbst anrt i II Nu, 3 -N ICCUMLn I at Io(

alir r irig at, rat ion was niot riot w (lar et 6) .Tlhe low i it alI conicrit rdat I oU

+eg . 0 . I I pg/n I ) of soluble Nil 4in the browns Lake svstemi did not

chainge ina rkel i v Iiti 14 days o)f- ae rajt I onl. rNrrrrrrorr i umi-N d s~rirpea red raip i di I

in the Redl Bock svst em; however, cenivers ron of Nil, - N to No, - N on lv4 13

jccomnted tor 1(0 percent of Ltre tot,ril inorganic N luring the 28-ivI\

ae rob i c I rrcrba t i of] perirod .

IlIlI III (of t rafstL afp Irc (iblcw ail[I~its of-( oXidized I nurg n I c N

accuilia ted, ma iirr i as NO. inr tihe waters wride r optimalI at ration coreli -

ions at 20'C Tablhe b) . Chirt et ;) 1. (1972) sirmilarly foundrr that t herr

wais a I - to 3-Ilay lag timet irelore r; it ri ti cat ion iegari. II rr lst 0t thle

sediiirert-witer svsteis , solutb le Nil , -A d(le ie e pr~aie riltc

ahIre levels unrder aerob ii coridit i ois ApprroxirrinaeI v 0.5 inrg/ I. ()t

ri i trate-N accumula tedl in Red Rock wi ter~. Ain est imated 6O pt'r(cert I,

tire soluble Nil - N ini the witers was- converted to oxidized f ormrs (If4

dunring 2 weeks of aerobic i neubhatin. These resuilts suggest tii.it sonmc

of the NO 3-N formred during nit ni i (at-ion inrteractedi withi tihe lifi isea

witer-serliment inter face. Further nit rite reduict ion reactioris, In[-

cluinirg nitrate imminob ili zat ion and den i tri fi cat ioin, coul 1 i ccminlt fIonI

tire loss of N in the waters. Tire raiites a t wh ic(It Nil, iS corlive rt en to

NO, 3 n ie rot) i c re se rvo i r wa tecrs aIre, snrrinia n- n zed i ii Ta bIE, 7 .

65

Phos phorius conictn-rat i Als III WatterI.

112. [t rrgari i c phospha tev (oi(eiit ra.it I ons I ( t he ove rI i g wajte

I(lah blet 8 ) dec rea sed wide r etrotic i c i(iiba t i oni I I tos t uf t tihe CL es

vol r sy st ems s hown . T[he o rtLho -pliospia t ( comit'ii t ra t Ionirsae I l .I 11 t tit

Browns Like sed iment -watetr syst eml) wh ich I flli ca tes t ha]t t a. to> t 11 1

systeml ot her thanl redox pot ent i a I ma e u t hei'Ies t i.

gat I c- pliospha t e t rom seti iiieiit to theit overI lv i ig wi t e rs .FI c t ('> I I i t -

Iiig theit releais e ofI ph os phoru Ls t- ror sedjiiiei tts t o overl I-II[Ig wi't t r I

d i s c uis s d Iii dle ta i I hly flo Id reni aid A rns t ronfg ( 1980) thetse c iu1t his 1

s ugge s ted thla t t he infc rea sed ('oncetit rait i o[iis oft i iiorgtjiti I [h i)-1rt i if itt

phospha te i n t he ove rIy infg wa t er i mmed ia tetI\ aft LerI ( erait I oni may ci

i nd Icated phys icalI suspeis ion of seii intent pa rt iclIes . Thttreft ore , ',ill

face sedlimtents caii he a possible source of P to awrohii c over lyinrg -tt cr

untier favorabhle envyi ronmnent al condfit ions sunch as wave indlutct ion a nd

mechan ical ci rciulat ion.

113. I n l aboratory anaerob ic ('(nt rol syst ems , i itorgaii i c pliosplite

concent rat ions reia inieti unchanged or intc rea sed w i t I incuba t i (,I)t time,.Al

overa I I est inmate of the di sappea rance rates of i niorgan i c phosphorus

under aerobi c cond i t ions i s shown in the t anij [aIt I i be l ow:

Rate of DI)sappt'i rtictDi)ssol vet iIior-gan li

Reservoi r Phospho ntis , g P/mI / day

Beech Fork Reservoir 0).007

Browns Lake -0. 0 05

Eagle Lake 0.035

Eaui Galfe Reservoir 0. NO

Richard Bi. Rtussel I Rese'rvoir 0. 146

Red Rock Reservo ir (0.020

I ron and manganteset ransformat ions itt the waters

1 [4. There wajs aI not iveiab It re Ie.1st' of it erroits i mun antd itaitganoits

manganese f romi reduiced sediment.s to antox ic wit ers (Table 9). Hlowevet'-

ti6t

o)x I da t loln o I I t-rros i roil aind reduced inanganese i it th( overl vi fig waiter s

OCCiirrt'd raplit IV onice aJerat loll beganri Coricerit rat lolls oit reduc(ed Iroll

dek I Inled drast I ca IIv to lbe I ow t he de tvc t ior] I irIIi t w i tIt i it I days oA

aerobi I llIcII lbiht io 0 I Table () ). A reddi sli-colored preci pi tate ill tin'

ait, ra ted ove'r Ii rig iat e r ii ntI ca t ed t haj t Ite rnr c oxyhvd rox i dets were' I )riiied

du i fiig tiestL ra Lt i ( atL on (iIif Iabo ra t ory s ys tenis

1 15. Simlulated dieSt rat i f i at loll al ISO (,Iect ivel V reiiiovel IMali-

galiese froiii thle a1i0XIC hIpo Iinion). ]In thle Eagle Lake systemii coit'i-

t tI-At lolls 0 t retiiCtd iiiJilgarie1Sc dec reast'd I roili abouit 2. 3 to l ess t Ila 1

). 05 p~g/iiii at ten 3 diys of au'rob)L i cIricuibat jolt. Resii I ts ind icated that

inore t han 90) perreni t Ofi redilced inAllgalieS0 il1 t I a I I V r e (I k I IS Ji)p1ea~ r ed

I rofl aerated aniox ic waters ii 2 weeks. Prec i pit at i on duinring oix i dat riln

may be the iios t i mpo rt ant way lin whic h ildigariese is remloved ill reseri-

volir ecosvs tems . The rait es at whi ich iieta Is were remnoved trout reicrated

anoxi c chambers are shown lit the t abii I at jonl below,:

Rates ofI Metai I iPieo I i I tl Io()[

8/11/1 iReservoir I roil (Ft, I I Nl I~igirco ~I I

Beech Fork Rese rvo i r- 2 0 5 . I tit

Browns Lake I . 141 o. ) 7o

Eau Gal Ic Reservoir 3. 707 o '

Eagle Lake I . t)-3 .:i

Richard B. RussellI Reservoir 3. 327 1

Red Rock Reservoir 0. 35 7 0n

In sit~u metal t rans format ions

116. A prel iminlary inl situl study valulated the' tet oft re-dilite

ron andl manganese in CE. resernvo irs duir inrg des trat if I i t loll OF 5 Lliit

aeration during Auigust 1981. The study provided the oxidait ion rites of

fe rroiis i ron anrd redluced manganese at Eaii (;a leI Rese wot r . ()itie ilylo-

1 imnetic locat ion was anoxic (site 1; stat-ion 20), .irid the other was

oxic (site 2; station 50) (Figure 21). Concenitrat ionis of so)lble riitaJIs'

recovered in Eau GallIe waters a fter 24 hir of inr siu hiricuhi,i ti )I-(, r

67

-~ -.4

SIN'fR ON

LOUSY

EAUGALE RVER TPA,GLL

fMNNE AP-, S LAKE

VICINITY MAP

STATION LOHN CRL[K20

SCALE

0 (Ii 02 KM

OUTLETSTRUCTURE

DAM

EAU GALLE LAKE

F i re 2 1 Map 0of Eau Gal Ilet Rese rvo i r- , W i s onjs ii1i

siimmarj zed in] the fo] I owing tabuIi at ion . Summer strait i ti cat i (In developed

a t s i te 1, aInd so 1111 1le metalIs predominated i u these anoxi C waters dunlr 11g

tl i ~s i nvest Li at ion.I ni cont ras t s si te 2 rerna i neil aerobi c dwe to I t s

shall Iow dlepth (0. 5 in).

C.incenrt rat ionis of Me(t a F, i 11 t he( Wajter I:,

lniciiat ion I roil Mang~aneseT eh-r Site1 St 2 Si te I S itev 2

0 -. 93 0.49 7 .13 5.9J8

24 9. 73 0. 17 3 .19) 2.54

The in it ial metal concent ratLion of 1:3. 3 mg/I. wajs based oii the mnet a Iinitially added to tile incubation bottle.

68

1 17. TIhe concerit rat ion of- so I uitbIe metalIs decreased( i i ariox I c tit d

ox Ic wajt ers a-ft Le r 24 h1r o t j in s i t it i nutba t i on . I it the ox i c wateIr

so I i)le i ron d Isappeared at a much f aster ra te t ha i sol I itlIe ma iga ntse

thei ariox i c hypo I inet I c waters did (Inot i rutL i all Iy cont a ill (it ectabId e

tlNiantt itL i e s o t so I Ut) I e i ron arid manga nese .Atte r 24 hir of III siti i nitifraj-

t I on , soI it) Ie i ron recove ry a ccoruriteul Ior 7:3. 3 arind 1. 3 pe r.en t of t tei

total tron i ri anox ic and ox ic waters, reslpect ive I y, wiile va fries t-r

so I ub I I, Mn we re 2 9 . 4 a rid 19 . I Pe rceri t , respec t I ye I y . RemovalI of the

sol ubfle met alIs f rom tie( waters may have been (III(- to oxidatilonl and p re-

p 1i1 tatL i oi orI d ispe rsalI . Es t i ma ted ox i da t i on ra tes of i ron arid mlanigaj-

Rest' il ile Ean Gall le reservoi r were 1 .26 and 0. 18 g/m L)/day , respec-

ively, at 22.5'C. These oxidation rates are similar to those obitained

i the lafuorat~orv.

118. Rate coe ffi cierits (level oped iii thie laboratory suich as have

been presented inl this sect ion of the report will formn the bas ic var1-i -

ab Ies inrput to the reae ration s rib rontine RE-AERS . These labfo ra to ry-

feve loped rate coetf Iici enits have agreed well withl rate coet'Ifi cienlt 5

mleasiuredtlin the f~ield at Eau Gaile Reservoir.

6D9

PART VI: SUMMARY AN[) CONCLIISIoNS

119. 'hrough a review of the literature anid disusslons with

authorities on aerobic nutrient and metal transformations, the t- fcts

of aeration and aerohic processes in lakes and reservoirs we rti c lomp ied

and organized. The most important of these processes were identil i .e

and used to formulate a realistic description of the pro(esses (tl frilg

during the change from anaerobic to aerobic condlitions. 'Ii s dsrIp-

t ion is presented i i Part II of t hIi s report.

120. The description then formed the basis t or the succ essftul

deve I opment of the aerob i c suhrout i tie RE-AERS , preseri ted in P I Lrt I I '1

this report. This subroutine is now ava i Iib I e f or i it( o , t . [I I ltnt

numerica I reservoir water qual I i ty models.

121. Sediment water react ionl chimbers of ler .t vilett Iv , 1

obtain i ng a b)road i ntormat ion base o t i riput vir ihl 1es inle n .1 coIltr I e,

etvi roriment . Data from these chambers are be i ig ob ti ned ,is .art o It i

Corps' EWQOS Program for lise in the RE:-AERS.

122. Appil cation of RE-AERS in a limllnit tt,,1 iiti I,1itv i-tlel t,

various CE reservoir projects using data ot ili ed 11(m the ii u ets I:, ,i

tool for examlnling the e tect ivellss ()t Varl()IS Iilh .lgelililir ,t .te ,

ipon1 probl(ms assot iatet with reac rit i n toii1l1 t (ii i ll s. [tiltl III lpI

conlitiotis ard through tit use of 'Liti obhta ilt'd lrn( nil;tw ghlo I gig budis

ot watek r, a water qua I ity model Ieqn i pped wit Ih R ,-A FRS :,lIuIId aI S() be

app I i cabl' to pre impoundnent i tivest i gat ions oI t Ii lIi ,t t , 1 s rt 1i i I 1-

cat ioni and dest rat i t i at iol.

7)

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Table 7

The Rate of N Transformations in CE Reservoir Systems Incubated

Under Aerobic Conditions at 200 C for 3 Weeks in the Dark

Rate of N)isappea rance

Nitrification Rate in the Waters

Reservoirs .g_ _N/m2/day _ _N/m 2/day

Beech Fork Reservoir 0.092 0.011

Browns Lake 0.014 -0.013

Eagle Lake 0.189 0.058

Eau Galle Reservoir 0.252 0.163

Richard B. Russell Reservoir 0.189 0.244

Red Rock Reservoir 0.015 0.171

Table 8

Changes of_ Inorganic Phosphate _(Ortho-P) Concent rat ion in the

Overlyin_Waters of Selected CE Reservoir Svstems

Under Aerobic Conditions at 25°C in the Laboratory

Change of Inorganic PhosphateConcentration at Part i c a r Hou rs, /

Reservoirs 0 1 3 6 14

Beech Fork Reservoir 0.106 0.104 0.077 0.062 0.02-)

Browns Lake 0.026 0.027 0.048 0.032 0.03E

Eagle Lake 0.100 0.005 0.005 0.0:] 0.014

Eau Galle Reservoir 0.367 0.020 0.005 0. 10 0.0'),-)

Richard B. Russell Reservoir 0.020 0.005 0. 030 0. 030 0. ) 2

Red Rock Reservoi r 0.120 0. 1,30 0. 105 0. 06, 0. O6)

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