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THE ROLE OF INORGANIC ION IMBALANCE IN AQUATIC TOXICITY TESTING
Citation:
Goodfellow, W. L., L. W. Ausley, D. T. Burton, D. L. Denton, P. B. Dorn, D. R. Grothe, M A. Heber, T J. NorbergKing, AND J. H. Rodgers Jr. THE ROLE OF INORGANIC ION IMBALANCE IN AQUATIC TOXICITY TESTING. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 19(175-182), (2001).
Description:
Effluent toxicity testing methods have been well defined, but to a large part have not attempted to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role that various total dissolved solids in effluents have on regulatory compliance has emerged during the last few years and has caused confusion in technical assessment and permitting/compliance issues. This paper assesses the issue of ionic strength and ion imbalance, provides a brief summary of applicable data, presents several case studies demonstrating successful tools to address toxicity resulting from salinity and ion imbalance, and provides recommendations for regulatory/compliance options to manage discharges with salinity/ion imbalance issues.
Effluent toxicity resulting from inorganic ion imbalance and the ion concentration of the effluent is pervasive in permitted discharge from many industrial process and municipal discharges where process streams are concentrated, adjusted, or modified. Procedures using weight of evidence approaches to identify ion imbalance toxicity discussed in this paper include: direct measurement, predictive toxicity models for freshwater, exchange resins, mock effluents, and ion imbalance toxicity with tolerant/susceptible text species.
Cost-effective waste treatment control options for a facility whose effluent is toxic because of TDS or specific ion(s) are scarce at best. Depending on the discharge situation, TDS toxicity may not be viewed with the same level of concern as other more traditional toxicants. These discharge situations often do not require the conservative safety factors of other toxicants. Selection of alternative regulatory solutions discussed in this paper may be beneficial rather than requiring potentially expensive or high-energy usage treatment options that may be ineffective control options.