Comprehensive approach to preparative isolation and fractionation of dissolved organic carbon from natural waters and wastewaters.

Ward and DeGraeve (6) have shown that SO2 was an effective way to eliminate the residual toxicity of chlorinated effluent. These investigators concluded that 17 freshwater fish and one macroinvertebrate were not affected after Sop dechlorination. Similar results have also been reported by other authors using various dechlorinating agents (29-32). Chlorine will likely continue to be used for biofouling control and disinfecting purposes by power plants and sewage treatment plants, respectively. Therefore, all feasible means to reduce the toxicity of this biocide should be thoroughly investigated in order to minimize effects on aquatic organisms. In this preliminary study we have demonstrated that dechlorination with sulfur dioxide is an effective means to reduce the toxicity of chlorine to striped bass eggs and larvae in an estuarine system. Striped bass ichthyoplankton exposed to dechlorination for exposure periods of 4 h or less experienced minimal mortality. In contrast, concentrations of TRC greater than 0.13 mg/L were found to cause high mortality to larvae after 4 h of exposure; therefore, SO2 dechlorination a t exposure periods of 4 h or less could completely eliminate mortality. We recommend future investigations on other estuarine organisms that may be subjected to SO2 dechlorination associated with industrial effluent. Future studies should be conducted to evaluate the effects of short exposures of ‘I’RC-SO2 followed by observation periods of several days in control conditions. This type of study would provide data on possible sublethal effects. The effects of interacting AT and dechlorination conditions should be evaluated in order to determine responses of aquatic organisms subjected to power-plant discharge conditions. Evaluation of possible acute and sublethal effects of halogenated organics resulting from dechlorination should also be evaluated.