The Community Structure Of Benthic Animals And The Evaluation Of Water Quality In Taihu Lake Basin In Zhejiang Province

This thesis mainly focus on the territory of the Taihu Lake Basin water resources survey in Zhejiang Province. We set 33 sampling sites, belong to four rivers including East Tiaoxi River, West Tiaoxi River, He River and the Beijing-Hangzhou Grand Canal. Field investigation and sampling were conducted in four quarters, the Summer Sampling was between July 19-August 2 in 2013, the Fall Sampling was between October 10-26 in 2013. the Winter Sampling was between January 4-19 in 2014, and the Spring Sampling was between April 12-26. Determination and analysis of the environmental indicators basin and macro benthos community structure, intended to Zhejiang Taihu Lake Basin Water ecological environment comprehensive evaluation.The research results are shown below. Firstly, most of the Taihu basin of Zhejiang province face serious eutrophication. the nitrogen and phosphorus content exceed the standard seriously. The average content of total nitrogen was 3.04mg/L, significantly exceeded national surface water standard Class V; TP and COD average values were 0.15mg/L and 28.01mg/L, both of them were in national surface water standard Class III-IV. The comprehensive nutrition index of the Beijing-Hangzhou Grand Canal is higher than the other three river systems, followed by East Tiaoxi River, while the highest of water quality is West Tiaoxi River with lowest index. In the second place, the average values of heavy metals in summer and fall were higher than spirng and winter of each site. Thirdly, the average content of chlorophyll-a was 0.84 g/L, not very high. Fourthly,40 species of macro benthos were collected, the average biomass was 479.2g/m2, the average density is 3054.3 ind./m2. Fifthly, four biological diversity index of water quality evaluation results show that the diversity index and species richness of the West Tiaoxi River was the highest, and the lowest is still the Beijing-Hangzhou Grand Canal, whose diversity was the worst. Lastly, according correlation analysis, the maximum correlation was between macro benthic density and chlorophyll (r= 0.487, P< 0.001), a very significant relationship.This study reveals initial that the Taihu Lake Basin in Zhejiang Province was in light-medial pollution, Meanwhile, the integrated use of biological diversity and physicochemical indices of basin water quality evaluation could reflect the long-term dynamic characteristics of the basin more accurately, which would benefit to mining pollution sources, provide theoretical basis for improve water quality of the Taihu Lake Basin in Zhejiang Province and the implementation of conservation measures.