Study On The Vertical Distribution Of Sedimentary Microbial Biomass, Species Of Carbon, Nitrogen, Phosphorus And Their Correlation

Vertical distributions of species of carbon, nitrogen, phosphorus and phosphor- lipid in the sediments of three sampling sites in a eutrophic shallow Lake Donghu were examined and analyzed. Meanwhile, the pH values and temperature was combi- ned to be studied at the same time. Based on the determination of vertical distributions of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), as well as micro- bial biomass(MB)in the sediments of three sampling sites, the relativities bet- ween biogenic matters and MB were studied.Results were summarized as follows:The pH values in sediments of Lake Donghu were lower than it in overlying water and decreased with depth. The highest concentration of TN (total nitrogen) and TP (total phosphorus) occurred in Station 1, where suffered from heavy domestic sewerage. The lowest concentration of TP and TN presented to Station 2, which is located at the centre of Lake Donghu. Also, the concentrations of dissolved ammoniac nitrogen (DAN) and dissolved nitrate nitrogen (DNN) of station 1 were higher than the other stations. In recent years, along with the pollution treatment measures, the concentration of TN and TP in station 1 presented a trend of decline. However, the concentration of TN and TP ascends very fast in station 3 and it has been as high as station 1 on the surface sediments. Although phosphorus is the most restricting nutritious element all the same, the concentration of TN descended greatly in the last two decades because of the combined effect of nitrification, denitrification and Phosphorus removing bacteria. As a result, the N/P ratio is only about 3.The highest concentration of microbial phospholipids occurred in Station 1and the average concentration is 59.40nmol/g·dw. The lowest concentration of microbial phospholipids presented in Station 2 and its concentration is 20.56nmol/g·dw. Station 3 was in the middle with its concentration at 31.57nmol/g·dw.Vertical distribution of three sample sites indicated that microbial phospholipids decreased along with...