Integrating Solute Transport, Stream

Metabolism and Nutrient Retention, using the Bio-Reactive Tracer Resazurin

Ricardo González-Pinzón, Roy Haggerty, Alba Argerich, Sarah Acker, David

Myrold

Outline

• Introduction• Current methods to estimate stream

metabolism • The resazurin-resorufin system • Metabolically Active Transient Storage

Introduction

Stream Response

Solute Transport

Stream Metabolism

Nutrient Dynamics

Introduction

Stream Response

Solute Transport

Stream Metabolism

Nutrient Dynamics

??

?

IntroductionThese knowledge gaps obscure the functionality of stream ecosystems and how they interact with other landscape processes.

Bencala et al., 2011

Introduction

Stream Metabolism & Sampling Limitations:– Benthic and hyporheic chambers, and

two-station diel technique.

Solute Transport vs. Nutrient Dynamics:– Weak or even contradictory

correlations using the Transient Storage Model (TSM).

Introduction: Stream Metabolism

Christensen 2010

Introduction: Stream Metabolism

(2009)

Introduction: Stream Metabolism

Introduction: Solute transport & Nutrient Dynamics

Hall et al. 2002

Introduction: Solute transport & Nutrient Dynamics

Working Hypothesis

Most metabolic activity and nutrient retention are associated with key active areas within TS zones, where biogeochemical gradients stimulate metabolism by aerobic microorganisms.

These zones are located in the near-subsurface of hyporheic zones and in the benthos of pools and eddies; they are referred to as the metabolically active transient storage (MATS) zones.

Drawing by Kera Tucker

Rru

Raz

Rru

Resazurin (Raz)

Resorufin (Rru)

Living organisms

Metabolically Active Transient Storage (MATS)

Metabolically Active Transient Storage (MATS)

quantified by Raz and Rru

MATS

Advection

Dispersion

MITS Sorption

MAIN CHANNEL

Exch

an

ge

Exch

an

ge

Fast

& S

low

decay

decay

decay

decay

Reaction and Degradation Rates

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

Measurements

Rat

es [

h-1

]

k1

k12

k2

10-5

10-4

10-3

10-2

10-1

100

101

k 1

k 12

k 2

Haggerty, Argerich & Martí, 2008

Transformation Rates

0.001

0.01

0.1

1

0.0001 0.001 0.01 0.1

c (mg/mL)

s (

g/g

)

Freundlich isotherm (shown):s = Kf c1/n

K f = 5.15 ± 1.34 mL/g1/n = 0.89 ± 0.04r2 = 0.993

Linear isotherm:s = Kd c

Kd = 6.63 ± 0.4 mL/g

r2 = 0.979

Rru- Sorption isotherm

Haggerty, Argerich & Martí, 2008

Complementary Sorption- Investigation

Methodology:

• Batch and column experiments to quantify the sorption of Raz and Rru.

• To prevent Raz transformation we will use sediments sterilized by gamma-radiation.

Quantitative relationship between ΔRaz and respiration

Vf-Raz = 0.26 ln(ER) + 0.47r² = 0.85 (p=0.01)

0.0

0.2

0.4

0.6

0.8

0.1 1.0 10.0

Raz

upta

ke v

eloc

ity

(V

f-Raz

mm

min

-1)

Ecosystem respiration (g O2 m-2 d-1)

Field Experiments

D Raz = 0.0019 D DO + 6 x 10-5

r² = 0.93 (p<0.001)0.E+001.E-042.E-043.E-044.E-045.E-046.E-047.E-04

0 0.05 0.1 0.15 0.2 0.25 0.3

ΔRa

z (m

mol

/L)

ΔDO (mmol/L)

Laboratory Experiments

y = 1.9x + 0.09R² = 0.91y = 6.8x - 0.01

R² = 0.93

y = 0.67x + 0.001R² = 0.99

y = 0.84x - 0.01R² = 0.98

-1.E-01

0.E+00

1.E-01

2.E-01

3.E-01

4.E-01

5.E-01

6.E-01

7.E-01

8.E-01

9.E-01

0 0.05 0.1 0.15 0.2 0.25 0.3

DR

az /

Co

D DO (mmol/L)

Oak Cr. Column exp. Clark Fork River. Column exp.

Fig. 3. McNicholl et al. (2007)-activated sludge Fig. 4. McNicholl et al. (2007)-activated sludge

[Raz]=10 ppm

[Raz]~200 ppb

Quantitative relationship between ΔRaz and respiration

Quantitative relationship between ΔRaz and respiration

Research approach:

• Batch experiments: aerobic bacteria and facultative anaerobic bacteria.

These experiments will restrict the transformation of Raz to biological mechanisms.

• Column experiments with different concentrations of Raz and varying physicochemical conditions to broaden respiration rates.

Study site: H.J. Andrews Experimental Forest, Oregon

Total reach length = 668.3 mTwo reaches

BEDROCK REACH

(357.5 m)

ALLUVIAL REACH

(310.8 m)

Argerich et al., in rev.

Two consecutive reaches:

Upper reach (bedrock reach): streambed sediments scoured to bedrock.

Lower reach (alluvial reach): deep alluvium.

22

N

Reach 2

Thick alluvium

with alder

Reach 1Bedrock

Flow

Argerich et al., in rev.

Longitudinal sampling 17 h since start of the injection

0 100 200 300 400 500 6000

50

100

150

200

250

300

350

400

0

20

40

60

80

100

Distance from the injection point (m)

bedrock reach

alluvial reach

Raz

(μ

g/L

)

Rru

(μg

/L) &

EC

(μS

/cm)

Argerich et al. (in rev.)

Raz sensitive to spatial heterogeneity

0

50

100

150

200

250

0 10 20 30 40 50 60

0

50

100

150

200

250

0 10 20 30 40 50 60

ALLUVIAL REACH

Raz

& R

ru (

μg

/L)

Raz

& R

ru (

μg

/L)

Time since addition started (h)

BEDROCK REACH

Raz (µgL-1)Rru (µgL-1)

Argerich et al. (in rev.)

f = 0.37 (MATS/TS)As/A = 0.19Mean travel time= 3.5 h

MATS = 0.002 m2

Raz reaction rate = 1.88 h-1

Raz reaction rate volume-weighted

= 0.13 h-1

f = 1.00 (MATS/TS)As/A = 2.45Mean travel time= 15.3 h

MATS = 0.291 m2

Raz reaction rate = 0.12 h-1

Raz reaction rate volume-weighted = 0.29 h-1

0.11 0.12 0.13 0.14 0.15 0.160.10

0.20

0.30

0.40

0.50

0.60

Instantaneous respiration rates (mg

O2m-2min-1)

Rru

:Raz

rati

o

y=1.29ln(x)+3.05R2=0.75, P=0.01

Raz to Rru proportional to whole-reach respiration rates

Argerich et al. (in rev.)

Respiration: alluvial = 2 x bedrock

Transient storage: alluvial = 13 x bedrock

Volume-weighted Raz reaction rate: alluvial = 2.1 x bedrock

Nutrient dynamics = f(MATS) Hydrologic processes:

DischargeTS

Biotic controls:Assimilatory uptake (algal mats,

microbes)Dissimilatory uptake (microbes)Consumers (macro-invertebrates,

fishes)

Abiotic controls: • Precipitation • Sorption

MATS: a linking tool between hydrologic and biologic nutrient retention

MATS: a linking tool between hydrologic and biologic nutrient retention

Methodology:• Column experiments with sterilized

and unsterilized sediments to differentiate biotic and abiotic nutrient retention.

• Injections of conservative (NaCl) and bio-reactive tracers (NH4, PO4, and Raz) monitored through time.

• In the field, we will measure the same injectates in surface upwelling/downwelling locations.

Applications in water resourcesMore robust techniques are needed to develop mechanistic relationships to improve our fundamental understanding of in-stream processes and how streams interact with other ecosystems

Water Resources Science

Water Resources Engineering

Water Resources Management

Understanding TS from a metabolic

perspective

Support to design stream

restoration projects

Support to design stream preservation

projects

Take-home points• Raz-Rru system is a “smart

tracer” for MATS– May allow us to worry less about

surface vs. subsurface transient storage and more about the rates of transformation in MATS.

– Transformation of Raz to Rru is proportional to aerobic respiration.

– Can help us to measure metabolism at different scales.

• MATS model can be used to differentiate metabolic activity in reaches and separate hydrologic and biologic effects.