Effects of brine addition on effluent toxicity and marine toxicity identification evaluation (TIE) manipulations

Abstract

AbstractLittle information is available concerning the effect of salinity adjustment on effluent storage and toxicity identification evaluation (TIE) performance. These factors are important for accurate assessments of potential toxicity to marine organisms. The objective of this study was to determine (a) the effect of salinity adjustment (to 30 ppt), using hypersaline brine (100 ppt), on the toxicity of effluents stored up to 40 d, and (b) to determine the effect of salinity adjustment on TIE manipulations. Changes in effluent toxicity over time were examined by using a municipal and an industrial effluent. A toxicity time series was performed for 16 d for the industrial effluent and 40 d for the municipal effluent. Toxicity was measured with modified 48‐h acute Mysidopsis bahia and Menidia beryllina tests Results indicate that, compared to day 0 test results, effluent stored with brine had fewer significant changes in toxicity than did effluent stored without brine To determine the effects of brine addition on TIE manipulations, we conducted a series of manipulations in which one aliquot of an effluent had brine added prior to the TIE manipulations and the other aliquot had brine added after the TIE manipulation The manipulations conducted were EDTA addition, sodium thiosulfate addition, C18 extraction, aeration, filtration, and graduated pH manipulations Toxicity was measured with the modified 48‐h acute mysid test. Addition of brine had no effect on the outcome of TIE manipulations. We have concluded that it is operationally easier to add brine as soon as possible after sampling and that effluent tests should be conducted as soon as practical