[Distribution and Pollution Assessment of Nutrients in the Surface Sediments of a Macrophyte-Dominated Zone in Lake Taihu].

To clarify the spatial distribution and pollution status of nutrients in the surface sediments from a macrophyte-dominated zone in Lake Taihu, total nitrogen (TN), total phosphorus (TP), alkali nitrogen (AN), available phosphorus (AP), and organic matter (OM) were measured at 60 sampling sites in Xukou Bay. A pollution evaluation and source apportionment analysis of these nutrients was also carried out. The average contents of TN, TP, AN, AP, and OM in the surface sediments of Xukou Bay were 1027.5, 423.2, 46.4, 15.3, and 17096.6 mg·kg-1, respectively, with the OM content being significantly higher in the northeast zone than in other areas of the bay. The average value of STN and STP was 1.75 and 0.91, respectively, indicating that TN and TP represent moderate and mild levels of pollution, respectively. The average comprehensive pollution index (FF) was 1.57, indicated that the surface sediment was moderately polluted. The observed organic pollution index indicated that the surface sediments in Xukou Bay were generally clean. Based on C/N values, organic matter in the surface sediments is derived from the bio-deposition of non-fibrous plants and phytoplankton. Based on correlation analysis, OM and TN in the surface sediments of Xukou Bay are derived from the same source, while TP is derived from an alternative source.

[Community structure of phytoplankton and its relationships with environmental factors in drinking water source of Jinshu Bay, Taihu Lake].

By using canonical correspondence analysis (CCA), this paper studied the community structure of phytoplankton and its relationships with environmental factors in the drinking water source of Jinshu Bay, Taihu Lake. A total of 7 phylum and 58 genera were identified, and the phytoplankton community was dominated by Cyanophyta, Bacillariophyta, and Chlorophyta. The quantity of phytoplankton was slightly higher in summer (250 x 10(4) ind x L(-1)) than in spring (238 x 10(4) ind x L(-1)), but the community structure differed obviously between the two seasons. In spring, Cyanophyta was the dominant phylum, and Anabaena was the dominant genus; in summer, Chlorophyta was the dominant phylum, with no dominant genus but abundant quantity of Merismopedia and Scenedesmus. Besides temperature, the main environmental factors affecting the distribution of phytoplankton in spring were ammonium-nitrogen, total phosphorus, total nitrogen, and phosphate, while those in summer were total nitrogen, ammonium-nitrogen, phosphate, suspended solids, macrophytes, total phosphorus, and transparency.