海水淡化浓盐水排放中挥发性卤代烃环境安全性评价

Environmental safety assessment of the volatile halohydrocarbon in the brine discharge from sea-water desalination

对天津大港新泉海水淡化有限公司排放浓盐水的6次水样中11种挥发性卤代烃质量浓度进行分析,依据3个基础营养级水平(藻、蚤、鱼)的急性毒性效应(L(E)C50),采用商值法对海水淡化浓盐水排放中的二氯甲烷、1,2-二氯乙烯、1,1-二氯乙烷、三氯甲烷、1,2-二氯乙烷、四氯化碳、三氯乙烯、二氯一溴甲烷、一氯二溴甲烷、四氯乙烯和三溴甲烷进行了环境安全性评价。结果表明,1,1-二氯乙烷、三氯甲烷和1,2-二氯乙烷3种挥发性卤代烃的环境质量浓度/无影响质量浓度(PEC/PNEC)比值大于1,存在一定生态风险。

This paper intends to present our study on the environmen- tal safety assessment of the volatile halohydrocarbon in the brine dis- charged from the sea-water desalination. For this purpose, we have analyzed the content concentration of 11 kinds of volatile halohydro- carbon in the 12 water samples from 6 different collecting months of the brine discharged from the seawater intake of desalination project affiliated to the Dagang Xinquan Ltd Company, Tianjin. In order to prevent the corrosion caused by the bacteria, alga and other marine organisms in the desalination process, bactericides, like chlorine or hypochlorite were commonly used, which are likely to react with the organic compounds in the seawater to form chlorinated organic com- pounds like volatile halohydrocarbon. Though their concentrations may tend to decline on account of degradation and dilution, it re- mains harmful to the aquatic organisms even at low levels. Therefore, it becomes of great significance to monitor the volatile halohydrocar- bon in the brine discharge so as to keep and promote the sustainable development of the desalination industry, later, we have identified the 11 kinds of halohydrocarbon in the water samples by using the headspace capillary gas chromatography. Besides, we have performed serious analysis of the toxic effects （（L（E） C50 ） from the three basic levels of aquatic organisms （ Scenedemus vacuolatus, Daphnia magna and Oncorhynchus mykiss ）. It is on the basis of all the above re- search activities that we have applied the quotient method from the Technical Guidance Document （TGD） on Safety Assessment of Chemical Substances by the European Union to the systematic assess- ment analysis of the ecological risks of the 11 kinds of volatile halohy- drocarbon in the brine discharged from desalination project and the seawater intake. The results of our analysis prove that the actual lev- els of volatile halohydrocarbon samples in the brine discharge from desalination project are all higher than that in the seawater intake, especially, than that of the 1,1-dichloroethane, trichloromethane and 1,2-dichloroethane prominent. What is more, the quotients of PEC! PNEC of i, 1-dichloroethane, trichloromethane and 1, 2- dichloroethane are also higher than 1, though those of the others were lower than 1. Among all the three pollutants, we have found that more attention should be paid to the trichloromethane, whose environ- mental concentration in the brine discharged from the project is 20.67 times as high as that of the free-from the effect concentrations.