The Research On The Pollution And Risk Evaluation Methods In Site Environmental Assessment

With city expanding, land resources becomes increasingly tense, so industrial enterprises in the city center have to be removed for releasing the land which can be used as residential land. However, the heavy metal pollution in this kind of land is getting much concerned, and soil pollution and health risks has become the focus of research these years.According to the references of past research and related publications, three stages of the site environmental assessment was summarized. First, through a survey of the site, the possible pollutions of the area were analyzed. Secondly, to sample the possible pollution area, then the results of the soil test were compared with the background and the State Standard of Class3Land respectively, the Nemerow index method was used to the assessment of the quality of the area soil. Through comparison the test results and the critical value of soil remediation, the area that had health risks could be find out.Finally, it should do detailed test in the area that had health risks, including the samples of the certain depth, then the carcinogenic and non-carcinogenic risk could be calculated by health risks assessment. The assessment analysised the ingestion pathway and the impressionable crowd of the pollutions, then soil remediation scheme is put forward that reduced health risks to an acceptable level.By searching the literatures, it did not set appropriate levels for residential land in the standard of soil environmental quality of our country, but according the established route the standard of soil environmental quality of residential land is three level at least. Besides the soil environmental quality standard, for the purpose of investigating the pollution degree of soil, it is the normal method that use the local background information to assess the pollution degree of soil. Because of the vast area and the kinds of soil, the background information of soil of different area is different. So it was done in this thesis that the maximum acceptable level of carcinogenic risk or not can be obtained by analyzing the concentration of a single pollutant of soil, and the result can be the reference values of assessing the health risk of pollutant in soil and judgments that the soil should be repaired or not.Adopting index method of integrated pollution for the environmental assessment about a site of machinery factory in Dalian city, it was obtained that two workshops had light pollution, and the other sites are safety. It was obtained that this kind of machinery factory has non-carcinogenic health risk of chromium and arsenic in soil for children by the direct ingestion after health risk calculation. It is suggested that the soil of electroplating factory and its periphery should be repaired by the methods such as mining, change the using pattern, etc. The pollution soil of wood workshop and its periphery should be degraded naturally by plowing, and then repaired by greening.