Levels of Dissolved Solids Associated Levels of Dissolved Solids Associated With Aquatic Life Effects in Virginia’s With Aquatic Life Effects in Virginia’s

Central Appalachian Coalfield StreamsCentral Appalachian Coalfield Streams

Tony TimpanoStephen Schoenholtz, David Soucek, Carl Zipper

VirginiMarch 29a Tech, 2011 1

BackgroundBackground• Question: what is TDS relationship to aquatic life?

• Challenge: TDS often with other stressors• Approach: Evaluate TDS effects with other stressors

minimized

2

Wayne Davis USEPAEcoAnalysts, Inc. EcoAnalysts, Inc.

Ephemeroptera(Mayflies)

Plecoptera(Stoneflies)

Trichoptera(Caddisflies)

Site SelectionSite Selection• Systematic: GIS prescreen, ground-truth• High-Quality Habitat• Avoid Non-TDS Stressors:

3

Iron Seep Sedimentation

Data CollectionData Collection• Field

– RBP Benthic Macroinvertebrates

– RBP Habitat– Temp, pH, DO, Cond.– Water grab samples– Fall 2008, Spring 2009,

Fall 2009, Spring 2010

• Lab– Family & Genus “bugs”, VASCI– TDS– Alkalinity (for HCO3

-)

– SO42-, Ca2+, Mg2+, Na+, K+, Cl–

– Al, Cu, Fe, Mn, Se, Zn

4R. J. KrenzR. J. Krenz

Site SelectionSite Selection&&

TDS CompositionTDS Composition

5

6

Results – Site SelectionResults – Site Selection• Non-TDS stressors not evident

– Habitat comparable to reference– pH 6.6 – 8.5– No obvious NPS Pollution

7

Reference Site (22 S/cm) Test Site (265 S/cm)

Test Site (1,670 S/cm)Test Site (594 S/cm)

8

TDS Mean Ion ProportionsTDS Mean Ion Proportions

9

Reference SitesMean TDS: 21 mg/L

Test SitesMean TDS: 406 mg/L

Test Site Mean Ion ConcentrationsTest Site Mean Ion Concentrations

10

Test Site TDS Seasonal VariabilityTest Site TDS Seasonal Variability

11

566n = 8

371n = 16

485n = 19

371n = 21

Means:

VASCI – TDS AssociationsVASCI – TDS Associations

12

Analyses that follow should not be interpreted to indicate actual, potential, or suggested water quality criteria for TDS or component ions.

Analysis MethodsAnalysis Methods

• VASCI = multimetric index of benthic macroinvertebrate community integrity (0-100 pts)

• Evaluate VASCI-TDS Relationship– Least Squares Linear Regression– Quantile Linear Regression

• Observed Effect Concentration (OEC) = TDS concentration where VASCI = 60

13

Correlations: Test SitesCorrelations: Test Sites

14

VASCITDS SC Ca2+ SO4

2- Mg2+ K+ HCO3- Na+

mg/L S/cm mg/LTDS -0.64SC -0.63 0.99Ca2+ -0.61 0.91 0.90SO4

2- -0.58 0.92 0.91 0.94Mg2+ -0.55 0.87 0.85 0.95 0.94K+ -0.54 0.90 0.89 0.82 0.83 0.81HCO3

- -0.42 0.64 0.67 0.45 0.38 0.35 0.63Na+ -0.35 0.34 0.37 0.31 0.67Cl- 0.30 0.58

Highly Correlated MeasuresMeasures Evaluated

all correlations significant (p < 0.05)

VASCI SeasonalityVASCI Seasonality

15

Reference Sitesn=6 n=9

Test Sitesn=27 n= 39

Spring VASCI scores > Fall VASCI scoresat test and reference sites

VASCI vs. TDS (LS Regression)VASCI vs. TDS (LS Regression)

16

Model SC (S/cm) TDS (mg/L) SO42- (mg/L)

Spring 768 528 336All - Year 634 422 219

Fall 523 337 143

OECs:VASCI = 60

VASCI vs. TDS (Quantile Regression)VASCI vs. TDS (Quantile Regression)

17

Quantile SC (S/cm) TDS (mg/L) SO42- (mg/L)

90 not sig. not sig. not sig.75 903 637 39250 625 421 21925 429 263 13310 281 142 48

OECs:VASCI = 60

Q90: 90th quantile = 90% of data below line

Q50: 50th quantile = 50% of data below line

Q10: 10th quantile = 10% of data below line

Q-value = probability of VASCI < 60

Observed Effect Concentrations (OECs)Observed Effect Concentrations (OECs)

• OEC = concentration where VASCI = 60

18

MethodProbability of VASCI < 60at OEC (%)

Model/Quantile (%)

SCS/cm

TDSmg/L

SO42-

mg/L

OLS Regression Fall 523 337 14350 All-Year 634 422 219

Spring 768 528 336

Quantile Regression 10 10 281 142 4825 25 429 263 13350 50 625 421 21975 75 903 637 392

Measured Values 0 All-Year 332 190 70100 All-Year 1,366 1,108 849

Probability of VASCI < 60Probability of VASCI < 60

19

ConsiderationsConsiderations

• OEC ≠ Toxicity• TDS Composition: SO4

2- and HCO3- dominant,

Ca2+ dominant cation• VASCI Seasonality: Spring > Fall• Variability of VASCI – TDS Association• Variability of TDS (Temporal)

20

Field Sensitivity Field Sensitivity DistributionsDistributions

21

Analyses that follow should not be interpreted to indicate actual, potential, or suggested water quality criteria for TDS or component ions.

Field Sensitivity DistributionsField Sensitivity Distributions

• Salt tolerance of individual benthic macroinvertebrate genera

• Maximum Field Concentration (MFC)– MFC = highest conc. where genus observed

• Cumulative Distribution Function (CDF) of MFCs

• X% Observed Effect Concentration (OECX)– OECX = conc. affecting X% of genera

22

Macroinvertebrate GeneraMacroinvertebrate Genera

• 97 genera• Excluded genera (37)

– < 4 observations/genus (5% of 81 samples)– Genera not at reference sites

• 60 genera used• Spring, Fall, All-Year models

23

TDS FSDsTDS FSDs

24

X% Observed Effect ConcentrationsX% Observed Effect ConcentrationsWater Quality

Parameter

Proportionof TaxaAffected

Model

Fall SpringAll-

Year

Specific Conductance (S/cm)5% 450 465 462

10% 476 511 49020% 653 647 652

TDS (mg/L)5% 273 291 281

10% 288 311 29820% 421 422 411

SO42- (mg/L)

5% 120 160 10810% 163 221 15620% 210 250 221

25

OrdersOrders

26

• Mayflies most sensitive (E)

• Stoneflies least sensitive (P)

ConsiderationsConsiderations

• OECX ≠ Toxicity

• Small Sample Size = Few Taxa• Method sensitive to rare taxa• Truly rare taxa? too few samples to know• Temporal variability of TDS

27

Further Research NeedsFurther Research Needs• TDS Temporal Variability

28

Data: DMME & VT

?

Questions?Questions?

Study Sponsors:Virginia Dept. of Environmental Quality

Virginia Dept. of Mines, Minerals, and EnergyPowell River Project

29