Geochemistry and Influence to Environment of Phosphorus in Modern Sediment in Dianchi Lake
XIA Xue-hui 1 DONG YE Mai-xing 1 ZHOU Jian-min 1 TIAN Sheng-ping 1 ZHANG Zhuo 2 PENG Yan-hua 2 1(Geological Institute of Chemical Minerals,Zhuozhou Hebei 072754) 2(Department of Biology, Yunnan University,Kunming 650091)
Phosphorus is an important element which produces eutrophication in lake sediment. People have paid special attention to the phosphorous research according to its content and geochemical activity as well as complenmineral characteristics in the lake. The total content of phosphorus in Dianchi lake is 10.3 times as high as normal data. The average content of P 2O 5 in bottom mud is 0.52%,and the highest content reaches 1.92%. There are many phosphorus mineral deposits,so the source of phosphorus in the lake is very rich. On the basis of statistics ,the phosphorus content has been increasing every year. The existing forms of phosphorus in Dianchi sediment are mainly in adsorbed form, organic form and combined with Fe,Ca,Al and Sb.These forms of phosphorus in the bottom mud are not stable, easily changing with environment,so phosphorus can be released into the water body again. Microorganisms play an important role in the circuation of phosphorus, lactate bacteria can resolve phosphate and make the content of soluble phosphorus increase in the lake. The enrichment of phosphorus can be due to assemble phosphorus bacteria and,after they die, the mineralization of the organic phosphorus is important way which result in hydrated phosphate deposit in the lake. When conditions are suitable, the unsteady hydrated phosphate is covered by sediment , after mineralization, it will become apatite in the end .