Analysis And Evaluation On The Comprehensive Effect Of Industrial Zone Downstream(Danshui River) Aquatic Envrionment Improvement

Danshui River is a tributary of West Zhijiang River, and the secondary tributary of Dongjiang River. The water quality affects the drink safety of millions of people. The Danshui River, in the industrial zone downstream, has suffered serious pollution and lost the basic function. In recent years, due to a series of remediation measures adopted by the government, the aquatic environment has been greatly improved. In this paper, the monitoring of the Danshui River Basin (Danshui River, West Zhijiang River, Dongjiang River) in wet season and dry season has been studied. And the current situation of water environment has been studied from the aspects such as water environment (including regular physical and chemical indicators, heavy metals, organic compounds) and aquatic ecosystems (phytoplankton, zooplankton, benthos and fish), which identifise the risk of river basin water environment, analyses of the effectiveness of remediation, and predicts the risk of water quality, finally puts forward some suggestions for the future research.The conclusions are as follows:(1) Conventional water index:water quality comprehensive index and eutrophication assessment demonstrates that from upstream to downstreamin the basin, the water quality had been deteriorating and nitrogen and phosphorus were the main pollution sources.(2) Heavy metal index:the heavy metal content in the surface water proves to be at lower levels and the condition of sediment of heavy metal pollution was more serious. Geo-accumulation Index Method and potential ecology risk index showed that Cu and Hg pollution was more severe, Mnand Cr pollution levels were relatively lower. Pollution source analysis results demonstrates that Zn, Ni, Cr, Mn and Pb are from the valley as well as developed electronic electroplating industry, while Hg and Cu from other industries.(3) Organic compounds index:high degree of nonylphenol, bisphenol A and low concentrations of triclosan could be widely detected in the basin. Surface water and sediment ecological characterization indicated that some point nonylphenol and bisphenol A showed high ecological risk.(4) Water ecological index:the population structure of phytoplankton, planktonic, benthic animal and Shannon-wiener Diversity Index, Pielou evenness index, Margalef richness index, showeed that, to some extent, the basin has been polluted.In addition, the detection of heavy metals in fish muscle indicates that heavy metal content was within the safe range.(5) CCA showes that the main environmental factors influencing the survival of phytoplankton were temperature, pH and nutrient, heavy metals and organic pollutants do not impose a serious impact on the survival of phytoplankton.(6) A series of measures such as flux reduction, ecological governance and environment management, in the basin have improved the water quality in recent years. However, there still were high concentration of nutrients, sediment contamination release, and organic concentration higher potential risk. It is urgent that measures be taken to guard against possible threats of Danshui River to water quality and safety in Dongjiang.