| With the Huaihe River valley's rapid urbanization, a substantial increase in non-agricultural population makes the lives of urban pollution greatly increased in the past 10 years. The continuous development of industry and agriculture production has been expanding in the process of dealing with poor economic development and environmental protection. Mass production and non-treated sewage were directly to the river in emissions, and the wastes were dumping to the river. In particular, it is inappropriate to develop a number of small paper mill, small leather mill, small chemical plant, and other industrial enterprises which have huge sewage capacity with poor social benefits.These all make the Huaihe River be extremely serious pollution. A great deal of the vicious incidents of pollution has frequently happened in the Huaihe River Area in recent years.The pollution made about 2/3 of the river lost its value. And the poor water quality has already caused drinking water problems in some areas. Along the largest tributary of the Huai River-the Shaying River, Henan Province Shenqiu County even has "cancer villages".The local villagers were suffering from cancer mortality rates which were significantly higher than the country's rural areas.In view of these, we take the Huai River main stream (including the upper and south reaches of the Huai River), the Shaying River, the Hongru River, the WhoRiver and the Shu River four tributaries as a research object. Conducted on the Huai River's main pollutants (including Nitrogen, Phosphorus, Heavy Metals and Persistent Organic Pollutants), multi-media distribution of them, distribution of microbial populations and the ecological risk assessment have been discussed in this work. The main findings are as following:Based on analyzing the spatial distribution of nitrogen and phosphorus in overlying waters, the present work revealed: the whole Huai River water was eutrophication. Nitrogen made a greater contribution to the eutrophication, ammonia as a major pollutant, but the region has a larger difference. Phosphorus made a relatively small contribution to the eutrophication of the Huai River, therefore, phosphorus may become the restrictive factor which would impact the growth of phytoplankton. The pollution has got the biological response of plankton, causing diatoms, green algae and cyanobacteria as a main component of phytoplankton, clearly show that the eutrophication of community characteristics.Through the discussion of the pollution of nitrogen and phosphorus in the sediments of the Huai River, the results demonstrated that the distribution of nitrogen in the sediments of the Huai River had a larger difference: the Shaying River and the main stream of the Huai River were less polluted by nitrogen, while the Hongru River was worse polluted. Organic nitrogen content in the sediments were more than 95%, while ammonia was the major inorganic nitrogen content. The Wo River and the Hongru River were worse polluted by phosphorus in the sediments, while the main stream was relatively less polluted.Through the cluster analysis of the content of the Heavy Metals in the surface sediments of the Huai River Area, the results demonstrated that the Zn, Cu and Cd in the surface sediments had a pollution identity. This revealed the close relationship between the entrance of the Heavy Metals and the emission from the metallurgical, chemical, coking, electroplating and leather industries on both sides of the Huai River. It is worth noting that, Cd existed mainly in exchangeable. Although the volume was very low, we need to be awareness and vigilance, because not only the exchangeable Cd would easily be released, but also Cd has strong biological toxicity. The study found that only uses the biological indicators of benthic fauna can not reflect the contamination of Heavy Metal in the study area. While the contents of Cr would impact the proportion of tolerance species (Oligochaeta) in zoobenthos. This shows that Oligochaeta could endure worse Cr pollution than sensitive species in the deposition environment.Based on analyzing the spatial distribution of PAHs in the sediments of the Huai River, the present work revealed that the contents of PAHs in the sediments of the tributaries of the Huai River were higher than the main stream. Because of the xomplex hydrodynamic condition of the gate dam, coastal pollution discharge and the contents of organic carbon in the sediments, the effect of sediment grain size on PAHs distribution was not significant. In addition, human activities, such as the sewage discharge, commercial shipping, and physical and chemical characters of sediments play an important role on PAHs multi-media distribution. 3-ring PAHs is a low-ring polycyclic aromatic hydrocarbon; it has certain toxicity. The study found that there is a significant negative correlation between the contents of 3-ring PAHs and the biomass of zoobenthos, which revealed 3-ring PAHs had certain toxic effects to zoobenthos.Through the study of aquatic biological communities constitute characteristics in the Huai River, the results showed that diatoms, green algae and cyanobacteria existed as a main component of phytoplankton, which clearly shown the community characteristics of the eutropnication. While the tolerance species--Oligochaeta benthic fauna was the absolute dominant species in zoobenthos. Visibly, water pollution in the Huai River was more serious as a whole situation.Based on environmental quality evaluation and biological diversity index of the Huai River system, the ecological risk assessment showed: the ecosystem of the middle and lower reaches of the Ying River where HD2 lies; of the middle and lower reaches of the Shu River where TPZ and WZZ lies; and of the middle and lower reaches of the Wo River where MC lies were badly damaged. The mutation point of the water ecological environment and water quality in the main stream of the Huai River is LHG. The water quality and the overall ecological environment of the main stream upriver LHG were pretty well while the lower reaches were deterioration. |
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