Levels of Dissolved Solids Associated
With Aquatic Life Effects in Virginia’s
Central Appalachian Coalfield Streams
Tony Timpano
Stephen Schoenholtz, David Soucek, Carl Zipper
VirginiMarch 29a Tech
, 2011
1
Background
• Question: what is TDS relationship to aquatic life?
EcoAnalysts, Inc.
EcoAnalysts, Inc.
Wayne Davis USEPA
Ephemeroptera
Plecoptera
Trichoptera
(Mayflies)
(Stoneflies)
(Caddisflies)
• Challenge: TDS often with other stressors
• Approach: Evaluate TDS effects with other stressors
minimized
2
Site Selection
• Systematic: GIS prescreen, ground-truth
• High-Quality Habitat
• Avoid Non-TDS Stressors:
Iron Seep
Sedimentation
3
Data Collection
• Field
• Lab
– RBP Benthic
Macroinvertebrates
– RBP Habitat
– Temp, pH, DO, Cond.
– Water grab samples
– Fall 2008, Spring 2009,
Fall 2009, Spring 2010
–
–
–
–
–
Family & Genus “bugs”, VASCI
TDS
Alkalinity (for HCO3-)
SO42-, Ca2+, Mg2+, Na+, K+, Cl–
Al, Cu, Fe, Mn, Se, Zn
4
R. J. Krenz
Site Selection
&
TDS Composition
5
6
Results – Site Selection
• Non-TDS stressors not evident
Mean RBP Habitat Score
– Habitat comparable to reference
– pH 6.6 – 8.5
– No obvious NPS Pollution
190
185
180
175
170
165
160
155
Ref
Test
7
Reference Site (22 mS/cm)
Test Site (265 mS/cm)
Test Site (594 mS/cm)
Test Site (1,670 mS/cm)
8
TDS Mean Ion Proportions
K
Na 3%
6%
Mg
4%
Cl
7%
Mg
7%
SO4
26%
K
Na
1%
6%
Cl
1%
Ca
13%
SO4
46%
Ca
11%
HCO3
43%
Reference Sites
Mean TDS: 21 mg/L
HCO3
27%
Test Sites
Mean TDS: 406 mg/L
9
FAW
GRA
CAW
SPR
FRY
HUR
RAC
RFF
SPC
RUT
ROL
LAB
JES
BIR
GIN
MIL
KEL
POW
KUT
CAN
RIC
Ion Concentration (mg/L)
Test Site Mean Ion Concentrations
1400
1200
1000
800
600
400
200
K
Cl
Na
Mg
Ca
HCO3
SO4
0
Site ID
10
Test Site TDS Seasonal Variability
1400
1200
TDS (mg/L)
1000
800
600
400
200
0
Fall 2008
Means:
566
n=8
Spring 2009
371
n = 16
Fall 2009
485
n = 19
Spring 2010
371
n = 21
11
VASCI – TDS Associations
Analyses that follow should not be interpreted to indicate actual, potential, or
suggested water quality criteria for TDS or component ions.
12
Analysis 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 Sites
VASCI
TDS
SC
Ca2+
SO42Mg2+
K+
HCO3Na+
Cl-
-0.64
-0.63
-0.61
-0.58
-0.55
-0.54
-0.42
-0.35
TDS
mg/L
SC
mS/cm
0.99
0.91
0.92
0.87
0.90
0.64
0.34
0.90
0.91
0.85
0.89
0.67
0.37
Ca2+
SO42-
0.94
0.95
0.82
0.45
0.94
0.83
0.38
Mg2+
K+
mg/L
0.81
0.35
0.63
0.31
HCO3-
Na+
0.67
0.30
0.58
all correlations significant (p < 0.05)
Measures Evaluated
Highly Correlated Measures
14
VASCI Seasonality
80
75
80
VASCI Score
VASCI Score
85
75
70
65
60
Fall
n=6
Spring
n=9
Reference Sites
70
65
60
55
50
45
40
Fall
n=27
Spring
n= 39
Test Sites
Spring VASCI scores > Fall VASCI scores
at test and reference sites
15
VASCI vs. TDS (LS Regression)
OECs:
VASCI = 60
Model
SC (mS/cm)
TDS (mg/L)
SO42- (mg/L)
Spring
All - Year
Fall
768
634
523
528
422
337
336
219
143
16
VASCI vs. TDS (Quantile Regression)
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
OECs:
VASCI = 60
Quantile
SC (mS/cm)
TDS (mg/L)
SO42- (mg/L)
90
75
50
25
10
not sig.
903
625
429
281
not sig.
637
421
263
142
not sig.
392
219
133
48
17
Observed Effect Concentrations (OECs)
• OEC = concentration where VASCI = 60
Probability of
VASCI < 60
at OEC (%)
Model/
Quantile (%)
SC
mS/cm
TDS
mg/L
SO42mg/L
50
Fall
All-Year
Spring
523
634
768
337
422
528
143
219
336
Quantile Regression
10
25
50
75
10
25
50
75
281
429
625
903
142
263
421
637
48
133
219
392
Measured Values
0
100
All-Year
All-Year
332
1,366
190
1,108
70
849
Method
OLS Regression
18
Probability of VASCI < 60
Prob. of Biological Effect (VASCI < 60)
1.0
1108
0.9
0.8
0.7
637
All
Fall Year Spring
337 422 523
0.6
0.5
421
0.4
0.3
0.2
Quantile Regression
OLS Regression
Measured
263
0.1
142 190
0.0
0
200
400
600
800
TDS (mg/L)
1000
1200
19
Considerations
• OEC ≠ Toxicity
• TDS Composition: SO42- and HCO3- dominant,
Ca2+ dominant cation
• VASCI Seasonality: Spring > Fall
• Variability of VASCI – TDS Association
• Variability of TDS (Temporal)
20
Field Sensitivity
Distributions
Analyses that follow should not be interpreted to indicate actual, potential, or
suggested water quality criteria for TDS or component ions.
21
Field 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 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 FSDs
24
X% Observed Effect Concentrations
Water
Proportion
Quality
of Taxa
Parameter
Affected
Specific Conductance
5%
10%
20%
Model
Fall
450
476
653
TDS
5%
10%
20%
273
288
421
5%
10%
20%
120
163
210
SO42-
Spring
(mS/cm)
465
511
647
(mg/L)
291
311
422
(mg/L)
160
221
250
All-Year
462
490
652
281
298
411
108
156
221
25
Orders
• Mayflies
most
sensitive (E)
• Stoneflies
least
sensitive (P)
26
Considerations
•
•
•
•
•
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 Needs
• TDS Temporal Variability
TDS (mg/L)
1500
?
1000
500
0
Jan 2005
Jan 2006
Jan 2007
TDS (DMME)
Jan 2008
TDS (VT)
Jan 2009
Jan 2010
Data: DMME & VT
28
Questions?
Study Sponsors:
Virginia Dept. of Environmental Quality
Virginia Dept. of Mines, Minerals, and Energy
Powell River Project
29
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