Research On Health Risk Assessment Method Of Organic Pollution In Groundwater Based On Solute Transport

Groundwateris an important part of water resource, it is an important water source for people’s life and industrial and agricultural production. In recent years, organic pollution of groundwater caused by human activities is increasingly serious, which brings a great threat to the health of water-users. Health risk assessment is an evaluation method which contacts the environmental pollution with human health. The possibility and degree of human health hazards caused by groundwater organic pollution can be effectively identified by assessing the human health risk caused by groundwater organic pollution, thus, it provides a scientific basis for groundwater management and restoration.A health risk assessment method of groundwater organic pollution based on solute transport theories and a corresponding health risk assessment index system are established by embedding the theories of groundwater solute transport into the four-steps way of Health Risk Assessment made by U.S.EPA:data collection&date evaluation, toxicity assessment, exposure assessment, risk attribute. Then they are used to calculate a set of organic contaminants’screening values for health risk assessment of groundwater pollution based on the quantitative relationship between exposure concentration and health risk values.Compared with the traditional health risk assessment methods, the new method can be more accurate in reflecting the harm of human health which caused by groundwater organic contamination under the current flow conditions,pollution source characteristics and degradation conditions, and it can identify the area where the health risk is unacceptable and the high risk area.Evaluating human health risk caused by the typical organic pollutants,1,2-Dichloropropane, in shallow groundwater of a contaminated sites located in Tianjin is used to demonstrating the new health risk assessment method, and the evaluation result is compared with the health risk assessment result ignoring concentration variation of1,2-Dichloropropane. The results show that:(1)In the study area, the peak of adult carcinogenic risk caused by1,2-Dichloropropane contamination of shallow groundwater is1.53×10-3, the area of carcinogenic dangerous zone (Risk>10-6)is almost23634m2, and the area of high carcinogenic risk zone (Risk>104) is nearly5426m2. The peak of children non-carcinogenic risk caused by shallow groundwater1,2-Dichloropropane contamination is10.3, the area of non-carcinogenic dangerous zone (HQ>1)is about23634m2, and the area of high non-carcinogenic risk zone (HQ>10) is only446m2.(2)Under the current flow conditions and degradation conditions, using the new method to evaluate human health risk caused by1,2-Dichloropropane contamination of shallow groundwater, which can effectively avoid overestimating the health risk in the area near the pollution source, and it can effectively identify a carcinogenic dangerous zone located the downstream of pollution source, the area of this zone is about4150m2, and the distance form this zone to pollution source range from166m to295m.