A Novel Approach to Developing Thresholds for Total Dissolved Solids Using Standardized and Experimental Toxicity Test Methods

• Published in: Environmental toxicology and chemistry Vol. 41; no. 11; pp. 2782 - 2796
• Main Authors: Brent, Robert N., Kunkel, Jared, Tomek, Zachary, Buchardt, Dalton, DeLisle, Peter F., Sivers, Sarah
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-11-2022; John Wiley and Sons Inc
• Subjects: Anthropogenic factors; Aquatic life; Aquatic organisms; Chlorides - toxicity; Composition; Criteria; Dissolved solids; Drinking Water; Ecology; Environmental Toxicology; Epichlorohydrin; Freshwater ecology; Freshwater salinization; freshwater toxicology; Ionic strength; Ions; Land use; Quality standards; Salinization; Sand; Sodium; Streams; Thresholds; Total dissolved solids; Total maximum daily load; total maximum daily loads (TMDLs); Toxicity; Toxicity testing; Toxicity Tests; Toxicology; Urban runoff; Water Pollutants, Chemical - toxicity; Water quality; water quality criteria; Water quality standards; Water supply; Freshwater salinization; total dissolved solids; freshwater toxicology; total maximum daily loads (TMDLs); water quality criteria
• DOI: 10.1002/etc.5466
• EISSN: 1552-8618
• ISSN: 0730-7268

The increasing salinization of freshwater streams from anthropogenic land uses and activities is a growing global environmental problem. Increases in individual ions (such as sodium or chloride) and combined measures such as total dissolved solids (TDS) threaten drinking water supplies, agricultural and economic interests, and the ecological health of freshwater streams. Because the toxicity of high ionic strength waters depends on the specific ion composition, few water quality standards exist to protect freshwater streams from salinization. In the present study, we used a novel approach to develop site‐specific and ecologically relevant TDS thresholds for the protection of aquatic life. The first step of the approach was to characterize the ion composition of the waterbody or region of interest and prepare artificial samples to match that composition. Using a combination of standardized toxicity test species and more ecologically relevant field‐collected species, toxicity tests were then conducted on these artificial samples prepared at a range of TDS concentrations. The advantage of this approach is that water quality criteria can be developed for easy‐to‐measure generalized parameters such as TDS while ensuring that the criteria are protective of instream aquatic life and account for the complex interactions of the various ions contributing to salinization. We tested this approach in Sand Branch, Loudoun County, Virginia, USA, where salinization from hard rock mining and urban runoff has impaired aquatic life. Acute and chronic TDS thresholds of 938 and 463 mg/L, respectively, were developed in this stream and used for total maximum daily load development in the watershed. The approach provides a potential model for establishing protective thresholds for other waterbodies impacted by salinization. Environ Toxicol Chem 2022;41:2782–2796. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.