[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.

[Spatial Distribution and Pollution Assessment of Heavy Metals in River Sediments from Lake Taihu Basin].

To clarify the pollution characteristics of heavy metals in the surface sediments of rivers in economically developed areas, analysis of the contents of eight heavy metals, assessment of ecological risks, and identification of the source of heavy metals in surface sediments from typical rivers of Lake Taihu Basin were carried out in this study. The results showed that the average contents of Zn, Cr, Ni, Cu, Pb, As, Cd, and Hg in the surface sediments of Lake Taihu Basin were 163.62, 102.46, 45.50, 44.71, 37.00, 13.34, 0.479, and 0.109 mg·kg-1, respectively. Except for Hg, the average contents of other 7 heavy metals were higher than their background values. The geo-accumulation index indicated that Pb, Ni, Zn, Cu, and Cd amount to a low pollution state. According to the pollution load index, Pb, Ni, Zn, and Cu represent a moderately polluted state, while Cd, Cr, and As a low degree pollution state. Based on the potential ecological risk index, Cd and Hg represent moderate potential ecological risk, and the others low potential ecological risk. Source identification of heavy metals by multivariate statistical analysis showed that Pb was largely from non-point pollutions; Cr, Ni, and Zn stemmed from electroplating, alloy manufacturing industries, and nature; Cu and As were mainly from pesticides and discharge of industrial wastewater; Cd was dominantly from smelting industry; and Hg was mainly derived from fossil fuel combustion and petroleum products.