In 2011, the United States Environmental Protection Agency (USEPA) released a field-based method for estimating the extirpation of freshwater aquatic benthic invertebrates by ionic mixtures dominated by HCO , SO , and Ca measured as specific conductivity (SC). The estimate of extirpation was SC at the 95 centile (XC95) of a weighted cumulative frequency distribution (CFD) of a genus or species over a range of SC. A CFD of XC95 values was used to predict the SC at which 5% of genera were likely to be extirpated. Because there are many uses for XC95 values and many data sets that could be analyzed using this method, we laid out a step-by-step method for calculating XC95 values and the stressor level that predicts a 5% extirpation of genera (HC05). Although the calculations can be done with a handheld calculator, we developed 2 downloadable Microsoft Excel® spreadsheet calculation tools that are easy to use to calculate XC95 values, to plot a taxon's XC95 cumulative frequency distribution with increasing SC, and to plot probabilities of observing a taxon at a particular SC. They also plot cumulative frequency distributions of XC95 values and calculate HC05 values. In addition to the tools, we share an example and the output of XC95 values for 176 distinct aquatic benthic invertebrates in Appalachia, in West Virginia, USA. Integr Environ Assess Manag 2018;14:174-180. © 2017 SETAC.
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http://dx.doi.org/10.1002/ieam.1993 | DOI Listing |
Environ Toxicol Chem
June 2019
Centre for Freshwater Ecosystems, School of Life Sciences, La Trobe University, Albury/Wodonga Campus, Victoria, Australia.
The use of field data to derive guideline water quality trigger values is likely to be more environmentally relevant than laboratory estimates. In the present study, macroinvertebrate responses to conductivity (specific conductance at 25 °C) within 5 bioregions in Victoria, Australia, were derived from 19 yr of macroinvertebrate field data. Varying response to electrical conductivity (EC) occurred among taxa.
View Article and Find Full Text PDFSci Total Environ
August 2018
U.S. Environmental Protection Agency, Office of Water, Office of Science and Technology, Health and Ecological Criteria Division, 1200 Pennsylvania Avenue, N. W., Washington, DC 20460, USA.
Field-collected measures of dissolved salts and occurrences of aquatic invertebrates have been used to develop protective levels. However, sufficiently large field data sets of exposures and biota are often not available. Therefore, a model was developed to predict the exposure extirpating 5% of benthic invertebrate genera using only measures of specific conductivity (SC) as the independent variable.
View Article and Find Full Text PDFEnviron Toxicol Chem
March 2018
US Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Cincinnati, Ohio.
Field data of fish occurrences and specific conductivity were used to estimate the tolerance of freshwater fish to elevated ion concentrations and to compare the differences between species- and genus-level analyses for individual effects. We derived extirpation concentrations at the 95th percentile (XC95) of a weighted cumulative frequency distribution for fish species inhabiting streams of the central and southern Appalachians by customizing methods used previously with macroinvertebrate genera. Weighting factors were calculated based on the number of sites in basins where each species occurred, reducing overweighting observations of species restricted to fewer basins.
View Article and Find Full Text PDFIntegr Environ Assess Manag
March 2018
Tetra Tech, Owings Mills, Maryland, USA.
In 2011, the United States Environmental Protection Agency (USEPA) released a field-based method for estimating the extirpation of freshwater aquatic benthic invertebrates by ionic mixtures dominated by HCO , SO , and Ca measured as specific conductivity (SC). The estimate of extirpation was SC at the 95 centile (XC95) of a weighted cumulative frequency distribution (CFD) of a genus or species over a range of SC. A CFD of XC95 values was used to predict the SC at which 5% of genera were likely to be extirpated.
View Article and Find Full Text PDFEnviron Pollut
September 2016
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Laboratory of Riverine Ecological Conservation and Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address:
Ionic mixtures, measured as specific conductivity, have been increasingly concerned because of their toxicities to aquatic organisms. However, identifying protective values of specific conductivity for aquatic organisms is challenging given that laboratory test systems cannot examine more salt-intolerant species nor effects occurring in streams. Large data sets used for deriving field-based benchmarks are rarely available.
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