Residues Character And Risk Evaluation Of Organochlorine Pesticides In Sediments Of Chaohu Lake

Chaohu Lake is located in the middle of Anhui Province ,left bank of the Yangtze River is a water system,and is one of the five largest fresh lakes in China ,also is the largest lake in AnHui. Therefore,it plays an important role on the economic development of surrounding areas and people's lives. In recent years, due to the development of industrial and agricultural production, Chaohu Lake increasingly serious water pollution, directly affecting the quality of life of the people, a threat to human health. It has no time to lose to evaluate the situation of the pollution of Chaohu Lake sediments.In order to know the status of organochlorine pesticide pollution of Chaohu, potential ecological risk in the degree of sediment pollution, the paper of Chaohu Lake and the main tributaries of the surface sediments were sampled to determine its distribution characteristics are analyzed, and left in the pollutants in sediment ecological risk assessment carried out. At the same time, the sediments of the organic chlorine content in the vertical distribution of research.1. The results show that the goal in the 19 kinds of pollutants, sediment has been detected in 15 kinds of organic chlorine compounds.Such asα- HCH,β- HCH,γ- HCH,δ- HCH,4,4'-DDE,4,4'-DDD,o,p'-DDT,P,P'-DDT,hexachlorobenzene, heptachlor, aldrin, endosulfanⅠ, endosulfanⅡ, heptachlor epoxide, endosulfan sulfate. The scope of the total content is 8.26～129.27ng/g, average content is 50.65ng/g. DDTs and HCHs were all detected, average contents are 29.02 ng/g and 11.77ng/g. The largest concentration detected is DDTs, the total content is 261.18 ng/g,of the total concentration of organochlorine pesticides in about 57﹪. The smallest content is Hexachlorobenzene, the average content is 0.78 ng/g.2.Organochlorine pesticides in sediments from the vertical distribution of these lanes are decreased down big; and have the highest level of OCPs in the upper sediments on the eastern half of Chaohu Lake and the main tributaries of organochlorine pesticides in sediments mainly in the surface of 0-3cm.3. According to DDT and biodegradable product of DDE and DDD in proportion to the content of the source of DDTs speculate, DDE/DDD ratio directs the degradable conditions of DDT. By the DDT contaminated soil after the long-term weathering, DDT/(DDD + DDE) is less than 1. The measured sediment DDT/(DDE+DDD)ratio of less than 2, that is from the early DDTs residues or pesticide residues in long-term weathering. Generally it,s believed that the DDT from the soil for the formation of aerobic microbial degradation product DDE. Measured from the point of DDT and the degradation product DDE, DDD ratio, the Lake of the points of the degradation of DDT mainly aerobic degradation products mainly DDE.4. Compared with home and abroad in the stream sediments of other organochlorine pesticides residue levels, Chaohu organochlorine pesticides in sediments at a moderate level of overall pollution.5. In this paper,with the standard risk assessment Ingersoll evaluate the organochlorine pesticides in ecological risk of Chaohu. According to testing, samples of organochlorine pesticides in sediments of the existence of a considerable amount of organic residues is greater than ERL, that sediments containing toxic pesticides have been more than 25% risk, but also a considerable amount of organic residues is greater than ERM, therefore Chaohu water sediments of organochlorine pesticides in some of the ecological risk, the river surface sediments in the region OCPs may cause harm to the ecological environment.