Presentation on theme: "Total Dissolved Solids: The Challenges Ahead"— Presentation transcript:
1 Total Dissolved Solids: The Challenges Ahead US EPA Region 3Freshwater Biology TeamWheeling, WV
2 Freshwater Biology Team, EPA R3, EAID, OMA FBT MembersAmy Bergdale, Frank Borsuk, Kelly Krock, Maggie Passmore, Greg Pond, Louis ReynoldsAssist the states in methods development, bioassessment, biocriteriaAssist EPA R3 in use of biological dataWQS, monitoring, TMDLs, NPDES, superfund, etc.Perform special studies
3 BackgroundMany states have identified “ionic toxicity”, conductivity and/or total dissolved solids (TDS) as a stressor or pollutant in their integrated lists.EPA has also identified TDS (and component ions) as a stressor impairing aquatic life.EPA lacks aquatic life criteria for TDS mixtures.Some TMDLs have been deferred due to lack of criteria.We also need criteria for effluent limits for discharge permits.
4 What We Know Some component ions are toxic to aquatic life. Ex. Mount et al 1997 , acute endpointsK+ > HCO3- =Mg2+ > Cl- > SO42-Laboratory fish are more tolerant than laboratory inverts.Test duration important.Chronic endpoints important.Resident fish are more tolerant than resident inverts.
5 Mount et al1997.C. DubiaMoreSensitive toTDS thanD. magna orfatheads.
6 What We Know Ion mixtures have varying toxicity Ion mixtures source specificAlkaline coal mine drainage (HCO3- , Mg2+, Ca2+, SO42- )Marcellus Shale Brine (Na+, Cl-,SO42-)Coal Bed Methane (Na+, HCO3- ,SO42-)
7 What We Know Effects synergistic, additive, or ameliorative Depends on the ions and their concentrationsIn some systems (e.g. Appalachian headwater streams) lab controlled toxicity tests are not a good predictor of instream aquatic life use impairment.
8 Two Webinars on TDS (2009)Toxicity testing approaches to develop criteria for individual ionsSurrogate organismsIowa: chloride and sulfateIllinois: sulfateEmpirical approachesbioassessment and water quality data to develop a criterion for an ion mixture:Ex. Alkaline mine drainage in southern WV and KY Appalachian streams.
9 The Case for Single Ion Criteria Lab experiments are controlledOther stressors are excludedToxicity testing data deemed more “defensible”Pollutant specific criteria instead of integrative parameters such as TDS or conductivityEasier to implement than narrative criteriaEasier to check compliancePermit writers understand itCan still incorporate site-specific conditionsResources will focus on source reductionRegulating TDS “futile”; Ion mixtures too complex.
16 Illinois Sulfate Criterion Illinois states that “Sensitive organisms reside in receiving streams with sulfate concentrations of 2,000 mg/L.”
17 The Case for an Empirical Approach Context is important.Aquatic life in small Appalachian streams is not the same as in Iowa or Illinois!We must protect the resident aquatic life uses.Unlike Illinois, we routinely see aquatic life use impairment downstream of alkaline mine drainage.Elevated TDS, hardness and alkalinity, in the absence of other stressors (e.g. habitat, low pH, metals violations).TDS and component ions are strongly correlated to this impairment.
18 Context is Important. What aquatic life are we trying to protect Context is Important. What aquatic life are we trying to protect? What is the natural water quality? What is the effluent quality?PAOHWVKYVA
26 Independent Datasets Confirm Sensitivity (West Virginia southern coal fields)9080706050% Mayflies40MinedUnmined30201050010001500200025003000Conductivity
27 EPA EIS data (WV) based on mean monthly WQ concentrations (n=13 months) TDS andIons stronglyCorrelatedTo mayfliesAnd impairment
28 Is aquatic life in small Appalachian streams more sensitive to TDS pollution than that in midwestern streams?Sensitive Mayflies:4070EpeorusEphemerellaAmeletusDrunellaCinygmulaParaleptophlebia6030504020% Sensitive Mayflies% Ephemerella302010100-200>10000-200>1000CONDUCTIVITYCONDUCTIVITY
29 Facultative/Tolerant Mayflies: What aquatic life is found in the midwest? Perhaps more TDS-tolerant invertebrates?Facultative/Tolerant Mayflies:501020304050607080% Tolerant Mayflies0-200>1000CONDUCTIVITYIsonychia, Tricorythodes, Baetis, Caenis403020% Isonychia100-200>1000CONDUCTIVITY
30 The Case for an Empirical Approach The concentrations of ions that are correlated with high probability of aquatic life use impairment are much lower than the toxicity testing data imply would be protective.Suggests that common toxicity testing organisms are not as sensitive as resident aquatic invertebrates.Many of the toxicity test results have been based on acute tests. The tests and endpoints should be chronic and the toxicity tests should test sensitive life stages.There may be seasonal issues due to insect life cycles.Empirical data may help us determine the more sensitive resident species.Bioassessment endpoints are the best tool to capture the total effect of a complex ion mixture.
31 Examples of ambient toxicity Chronic effects were detected in samples with field conductivity >1800 µS/cm.There is NO dilution capacity in these streams.
32 Chronic Effects Levels Estimated conductivity at EC25 % ranged from with an average of 820 µS/cm.This range is slightly higher than where we see effects with resident biota.
33 C. dubia more tolerant than resident Aquatic Life Ref for GLIMPSSNot tox testedAll sites were rated impaired using the genus level GLIMPSS (<66) , which directly measures aquatic life use impairment. The resident biota are more sensitive than the WET surrogate, C. dubia. Can’t use C. dubia alone to express “safe” thresholds, but it can be used as an indicator of the more toxic discharges.
34 Using Empirical Data Linear regression Quantile regression Conditional Probability AnalysisRegression TreesNoteconductivity of uS/cm approximates sulfate of mg/lIowa sulfate criteria ranges mg/lIllinois sufate criteria in range of mg/l
38 Ex. Conditional Probability Approach Paul and McDonald (2005) CPA relies on a large dataset to develop criteria.Simply asks “what is the probability of impairment given conductivity value ≥ x”?P(y|x) where y is impairment threshold (IBI), and x is some TDS or conductivity value.J. Paul (EPA, RTP, in review) found100% chance of MAHA sites being impaired when conductivity >575 and100% chance of Florida streams impaired when conductivity >750
39 Ex: CPA: WV DEP data: Summer pH>6 Probability ofImpairmentOver 90% whenCond > 500Probability of impairmentN=949RBP HAB>130Conductivity
41 How do these empirical results compare to Iowa’s Sulfate Criteria? We have not reviewed any bioassessment data from Iowa.R3 Empirical examples suggest impairment at sulfate mg/l
42 Water Quality Based Approach to Pollution Control DetermineProtection Level(EPA Criteria/State WQS)Measure ProgressConduct WQAssessment(Identify Impaired Waters)Monitor and EnforceCompliance(including instream bioassessments)Set Priorities(Rank/Target Waterbodies)Handout 2-6Water Quality Based Approach is outlined in Sec. 302 of the ActShow Video?(Do we need to review transcript to make sure it is OK?)Establish SourceControls(Point Source, NPS)Evaluate Appropriatenessof WQS for Specific Waters(Reaffirm WQS)Define and AllocateControl Responsibilities(TMDL/WLA/LA)
43 RecommendationsDo not rely solely on toxicity testing to determine protective limits.Consider chronic toxicity testing endpoints.Consider dilution ratios.Combine toxicity testing and empirical data approaches when field data are available.
44 Recommendations Prepare a technical support document on TDS reflects acute and chronic toxicity testing literatureoffers some examples of empirical datasets and how they would be used to characterize aquatic life, and develop, refine or evaluate criteria and permits.
45 RecommendationsAlways use bioassessments to assess aquatic life uses downstream of discharges with TDS.These data should feed back into the permit and possibly result in site specific criteria.Reflect all toxicants in dischargeProtect actual aquatic life that should be residing in that stream type
46 Ongoing Research - Surrogates Toxicity of TDS to surrogate lab organismsReview literature for TDSDevelop empirical datasets between TDS and aquatic lifeAcute and chronic tests with mining effluent and reconstituted salts and surrogate organisms (e.g. C. dubia)USGS Columbia Lab, Duluth EPA LabPreliminary Data…Hassell et al 2006
47 Ongoing Research - Natives Metal and osmotic ecophysiologyDeploy insects in situ – sample individuals in a time courseMeasure growth, metal and electrolyte content, subcellular compartmentalization of metalsExplain any differences in metal tolerance, bioaccumulation and toxicityLaboratory ExposuresMonitor oxygen consumption, osmoregulatory status and Adenosine triphosphate (ATP) levelsCharacterize “energetic costs” to living in high conductivityOutcomeProvide information on whether metal uptake is contributing to impairmentProvide information on mechanism for TDS impairmentNorth Carolina StateBuckwalter et al, 2007
48 Discussion Where do we go from here? Technical Barriers? Non-Technical Barriers?What do you need from EPA?What can you expect from EPA?How do we advance aquatic life criteria?How do we advance TMDL development?