Technical Guidelines for the Generation of Water Quality Criteria§

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Technical Guidelines for the Generation of Water Quality Criteria§

TABLE 3 - RANK GMAVSGMAVSMAVRANK (µg/L) Species (µg/L)4 100 Rainbow Trout, 100Oncorhynchus mykiss3 36 Cladoceran, 42Daphnia ambiguaCladoceran, 38Daphnia pulexCladoceran, 29Daphnia magna2 25 Amphipod, 25Gammarus pseudolimnaeus1 19 Amphipod, 19Hyalella azteca


Aquatic Life WQC CalculationRank Genus Mean Acute Values(GMAV) and Calculate the Percentileof Each Rank (100 R/(N+1))Supporting Data for Criteria100Rank Percentile80604020GMAVChronic Endpoints00.01 0.1 1 10 100 1000 10000 100000Concentration (ug/L)Using the 4 Most Sensitive Genera,Perform a Least Squares Regressionof the GMAV 2 (log values) on thePercentile Ranks (square roots)


100000COPPER - FRESH WATER SPECIESAdjusted To Hardness = 50 mg/LConversion Factor = 0.96Data: EPA, 1996TOTAL RECOVERABLE Cu GMAV (ug/L)10000100010010GENUS:1 - Ceriodaphnia2 - Daphnia3 - Ptychocheilus4 - Gammarus5 - Plumatella1XX X X XXXXX XXXXXX XXXXXX XXXXXXXXX XXX XXXFathead5 XXXXMinnow42 3 XXX FAV = 14.57 ug/LCMC = FAV/2 = 7.285 ug/LFCV = FAV/ACR = 5.161 ug/LX10.1 1 10 20 50 80 90 99 99.9PERCENTILE


CALCULATE CMC• Toxicity Related to WQ Characteristic?• Check Agreement within Species• Check Sensitive Life Stages• Calculate Species Mean Acute Values• Calculate Genus Mean Acute Values• Rank GMAVs• Calculate Cumulative Probability• Calculate Final Acute Value• Divide by 2 for CMC


CADMIUM FRESHWATER CRITERIAUSING HARDNESSCriteria Equation* = e(1.0166 (ln Hardness) – 3.924)Hardness(mg/L)EquationCriteria Value(µg/L)501002001.1e(1.0166 (ln 50) - 3.924)e (1.0166 (ln 200) - 3.924 4.3e(1.0166 (ln 100) - 3.924)2.1


ACUTE-CHRONIC CHRONIC RATIO (ACR)The Acute-Chronic Ratio Is Used ToQuantify the Difference in the ToxicitiesObserved in an Acute Test and aChronic Test.


CALCULATION OF FINAL CHRONICVALUE FROM ACUTE-CHRONICCHRONICRATIO1. Perform Acute and Chronic Testing Using Same Species in SameDilution Water2. Use Results to Calculate Acute-Chronic Ratios (ACR)Acute ValueACR =Chronic Value3. Develop a Final Acute-Chronic Ratio (FACR) by taking aGeometric Mean of the appropriate Acute-Chronic Ratios4. Calculate the Final Chronic Value (FCV) using the FinalAcute-Chronic RatioFCV =Final Acute ValueFACR


CALCULATE FINALCHRONIC VALUEAre Data Availablefrom 8 Families?Is Toxicity Related to aWQ Characteristic?Calculate FinalChronic EquationNoYesNoYesCalculate Species MeanAcute-Chronic RatiosUse Calculation of FAVProcedures To CalculateFinal Chronic ValueDo Ratios Fit Any of the4 Specified Cases inGuidelines?NoA Final Chronic ValueCannot Be CalculatedYesCalculateFinal Chronic Value:Final Acute ValueFinal Acute-ChronicRatio


Water Quality Criteria ConcentrationFinal Acute Value (FAV)FAV = 5 th percentile LC50Criterion Maximum Concentration (CMC)CMC = FAV/2“1/2” converts LC50 to LC0 = concentration that causes0% mortality (almost)


Chronic CriteriaBest SolutionThe 5 th percentile NOEL for lifetime exposure from theminimum databaseProblemUsually sample size too smallCurrent Solution – Acute to Chronic Ratio (ACR)1. Compute the ratio of Acute LC50 to Chronic L(N)OELfor each species with data2. Use the median ACR3. Criterion Continuous Concentration (CCC)CCC = CMC / ACR


CommentaryAssumes that the median ACR applies to the 5 thpercentile species – i.e. that the ACR is a constantPossible SolutionsDerive the chronic criteria (5 th percentile) directly


Exposure Duration – Averaging PeriodHistorical SolutionApply to an instantaneous concentration in the waterbodyProblem1. LC50 varies with varies with exposure time24 hr LC50 > 48 hr LC50 > 96 hr LC50 …2. Concentrations fluctuateNeed a single concentration (time average) to comparewith CMC and CCC.


Obvious SolutionMatch to test exposure timeAcute (CMC) = 4 dChronic (CMC) = organism lifetime = …ProblemTime to death is not related to exposure timeFast acting versus slow acting toxicants


Number Alive108642Slowing actingMortality vs TimeRapidly acting00 20 40 60 80 100Time (hr)


Current SolutionCriteria Averaging PeriodAssume all toxicants are fast actingAcute criteria:1 hr. ( = 1 day in practice)No good justification for thisChronic criteria:4 daysCorrect SolutionAcute criteria:Averaging period is related to time to death for theparticular toxicantChronic criteria:It depends…


Averaging Periods15Concentration (mg/L)105ChronicCriteriaAverage00 10 20 30 40 50 60Time (days)


Concentration (mg/L)1050Averaging Periods0 20 40 60Time (days)ChronicCriteria4 DayAverage

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