| Taihu lake is important fresh water resource in the basin. In recent years, Along with the rapid development of industry and agriculture of the watershed and population explosion, A large number of industrial and agricultural wastewater and solid waste is going to Taihu lake, Which completely beyond the self-purification capacity of the lake, leading to water quality worsening. Eutrophication degree deepening and even appeared "lake flooding" phenomenon.Lake water quality and ecological environment condition have close relation with submerged plants and algae, the two kinds of main primary producers, Which are inhibition on each other. Taihu lake area is broad, so the regional ecological system and environmental conditions are obviously different, presenting phytoplankton and macrophyte dominated zones, two different lakes state of coexistence phenomenon. Taihu lake sediments of lake water quality has important influence on internal phosphorus loading, two types of lake sediment phosphorus fractions, the law of buried and comparative study of endogenous load risk helps to further understand the different types of differences and the reasons of the eutrophication process of Taihu lake and provide relevant basis knowledge for Taihu lake eutrophication management.The study is in the east and west of Taihu lake, chosening the phytoplankton and macrophyte dominated zones in Taihu lake as the research site, respectively. In March, 2015 to collect water and core sediment samples. The eutrophication status, sediment physical and chemical indexes (moisture content, pH and OM) and the occurrence of phosphorus fractions are analyzed, and combined with the internal phosphorus loading simulation experiment, the risk of endogenous loading was studied. The main research results and the relevant conclusion is as follows:1. The main pollutant in the phytoplankton and macrophyte dominated zones in Taihu lake is CODMn and TN; The results of the comprehensive water quality identification index method for 3.020 and 4.021, So the water quality is III and IV class water, respectively; The phytoplankton and macrophyte dominated zones in Taihu lake results is 59 and 75, respectively. According to two types of lake eutrophication of mild and severe eutrophication, respectively. Reflect the characteristics of Taihu lake Phytoplankton and macrophyte dominated zones in Taihu lake water body overall difference.2. The moisture content of the phytoplankton and macrophyte dominated zones in Taihu lake sediment in different depth is 70.0～37.9% and 63.6～41.2%, average 50.9% and 47.2%, respectively. The moisture content of top-down decreases, the moisture content of the macrophyte dominated zones sediment type is greater than the phytoplankton dominated zones; The phytoplankton and macrophyte dominated zones in Taihu lake sediment pH average was 7.0±0.2; In addition, the macrophyte dominated zones lakes sediments OM average of 1.7%, greater than the average of 1.3% of the phytoplankton dominated zones.3. The macrophyte dominated zones sediment combined forms of phosphorus and TP, OP and IP concentration vertical distribution is relatively uniform, range in 287.8～335.0 mg/kg,214.2～277.8 mg/kg,42.4～103.6 mg/kg, variation range is small. The phytoplankton dominated zones in Taihu showed a trend of gradual increase in from bottom to top, range in 300.5～690.1 mg/kg,263.2～574.4 mg/kg and 34.3～115.8 mg/kg. The sediment P concentration reflected the phytoplankton and macrophyte dominated zones in Taihu phosphorus burial regularity of significant differences, The macrophyte dominated zones in Taihu sediment P accumulation quantity is little and stable, while the The phytoplankton dominated zones in Taihu buried lakes P to reflect the taihu lake in recent decades of typical characteristics of accelerating eutrophication process.4. Indoor columnar core sample method was used to simulate the endogenous release. Under the aerobic condition, the columnar core sediment release rate of TP in The phytoplankton and macrophyte dominated zones in Taihu lake were 2.80,3.02 mg/(m2·d), phosphate release rate were 1.99 and 2.37 mg/(m2·d); Under anaerobic conditions, The lake columnar sediment release rate of TP were 6.49,7.30 mg/(m2·d), PO43--P release rate were 2.60,5.43 mg/(m2·d). Therefore, The phytoplankton dominated zones endogenous release risk is greater than the macrophyte dominated zones in Taihu lakes. The release of phosphorus in the short term, then stabilise due to adsorption.In conclusion, This study from the perspective of endogenous load prove the phytoplankton dominated zones on the stability of the sediment, which is great significance in reduce the risk of endogenous load and maintain water quality and water ecological health. |
PDF Full Text Request