Heavy Metal Pollution In The Qin River

In this study, we carried out a comprehensive investigation and analysis of the overall pollution situation in the Qin River from the perspective of the health in rivers, which combined with the indicators of river health assessment and two typical environmental pollutants (Organochlorine pesticides and heavy metals), for the purpose of providing scientific basis for the governance of Qin River.We evaluated the Qin River from three aspects, including the eutrophication, the quality of habitats and the population structure of the benthic fauna. Then, we analyzed the content of TN and TP by the means of weighted average index, took the systematic assessment on the quality of habitats in Qin River by the way of Alan Baxter, and analyzed the population structure of the benthic fauna using the Margalef richness index, the Shannon-Weiner diversity index, the Pielou evenness index, etc. Results showed that the quality of water in the Qin River had the risk of eutrophication as a result of excessive phosphorus content. From the analysis of habitats quality in Qin River, we conclude that the overall habitat quality in the Qin River is good, of which only27%had poor quality. In the four counties of this survey, the benthic animal communities of Anze and Qinyuan were better while those of Qinyang, the worst. The overall health situation in Qin River is good, but certain cities and counties were in the status of sub-health that had the ecological risk. So we must strengthen the regulation in Qinyang in order to prevent further ecological harm from taking place.We determined the contents of HCHs and DDTs in the main stream and sediments in Qin River using GC-ECD, analyzed its composition and sources, and compared the content of organochlorine pesticides with the other rivers. Data showed that most sampling sites had the organochlorine pesticide residues in the main stream and sediments of the Qin River. The results showed that the total concentrations of HCHs were in the range of nd～2.23ng/L, and DDTs were in the range of nd～19.35ng/L in the water samples; the total HCHs ranged from nd～13.72ng/g with and the total DDTs ranged from nd～14.02ng/g in surface sediments. From the analysis of composition characteristics, we found that there was no new input of the industrial HCHs in the midstream of the Qin River, while Lindane might exist in the downstream of the Qin River; there was new input of DDTs near the middle and lower reaches of the Qin River that mainly come from dicofol and historical residues. Moreover, the contents of HCHs and DDTs of Qin River were similar to those of the Yellow River, which showed a close relationship to Yellow River in the level of migration and transport. All in all, the content of organochlorine pesticides in Qin River was in a medium level in the world, so its risk of being polluted is not great.The concentrations of heavy metals in sediments, water and benthic animals of22samples sites in5counties were determined using atomic absorption (AAS). The vertical distribution pattern of sediments and different forms of metals was determined. The environmental risk assessment and pollution sources and history was conducted using such methods as Sediment quality guidelines (SQG)and Potential ecological risk index (PERI) and The Ratio of secondary (RSF)and Primeval and phase enrichment factor(SEF). Results showed that,(1)The metals of water in Qin River was below the national standards of surface water.(2) There may have been Pb, Cu pollution in the middle and low reaches in the past, which has gradually eased; and there may exist a continuous source of Cr, Cd pollution in the Qinshui county; recently Zn was found in the river which didn’t form the threat of pollution; Cu had the hidden potential of ecotoxicity.(3)Base on the SQG,63%samples of Zn and81%samples of Cr was above the LEL level.(4)In the five counties along the Qin River, the contents of heavy metals in Qinshui and Anze reached to the strong ecological risk.