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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
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BackgroundBackground• Question: what is TDS relationship to aquatic life?
• Challenge: TDS often with other stressors• Approach: Evaluate TDS effects with other stressors
minimized
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Wayne Davis USEPAEcoAnalysts, Inc. EcoAnalysts, Inc.
Ephemeroptera(Mayflies)
Plecoptera(Stoneflies)
Trichoptera(Caddisflies)
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Site SelectionSite Selection• Systematic: GIS prescreen, ground-truth• High-Quality Habitat• Avoid Non-TDS Stressors:
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Iron Seep Sedimentation
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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
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Site SelectionSite Selection&&
TDS CompositionTDS Composition
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Results – Site SelectionResults – Site Selection• Non-TDS stressors not evident
– Habitat comparable to reference– pH 6.6 – 8.5– No obvious NPS Pollution
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Reference Site (22 S/cm) Test Site (265 S/cm)
Test Site (1,670 S/cm)Test Site (594 S/cm)
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TDS Mean Ion ProportionsTDS Mean Ion Proportions
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Reference SitesMean TDS: 21 mg/L
Test SitesMean TDS: 406 mg/L
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Test Site Mean Ion ConcentrationsTest Site Mean Ion Concentrations
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Test Site TDS Seasonal VariabilityTest Site TDS Seasonal Variability
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566n = 8
371n = 16
485n = 19
371n = 21
Means:
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VASCI – TDS AssociationsVASCI – TDS Associations
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Analyses that follow should not be interpreted to indicate actual, potential, or suggested water quality criteria for TDS or component ions.
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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
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Correlations: Test SitesCorrelations: Test Sites
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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)
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VASCI SeasonalityVASCI Seasonality
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Reference Sitesn=6 n=9
Test Sitesn=27 n= 39
Spring VASCI scores > Fall VASCI scoresat test and reference sites
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VASCI vs. TDS (LS Regression)VASCI vs. TDS (LS Regression)
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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
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VASCI vs. TDS (Quantile Regression)VASCI vs. TDS (Quantile Regression)
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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
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Observed Effect Concentrations (OECs)Observed Effect Concentrations (OECs)
• OEC = concentration where VASCI = 60
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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
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Probability of VASCI < 60Probability of VASCI < 60
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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)
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Field Sensitivity Field Sensitivity DistributionsDistributions
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Analyses that follow should not be interpreted to indicate actual, potential, or suggested water quality criteria for TDS or component ions.
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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
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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
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TDS FSDsTDS FSDs
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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
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OrdersOrders
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• Mayflies most sensitive (E)
• Stoneflies least sensitive (P)
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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
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Further Research NeedsFurther Research Needs• TDS Temporal Variability
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Data: DMME & VT
?
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Questions?Questions?
Study Sponsors:Virginia Dept. of Environmental Quality
Virginia Dept. of Mines, Minerals, and EnergyPowell River Project
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