Research On Vertical Distribution Of Phosphorus Forms In The Sediment Of Taihu Lake

Eutrophication of Taihu lake is becoming a major water pollution problem with consequence of development of social economy. The internal release of phosphorus from sediment plays an important role in maintaining eutrophic status in Taihu lake. The assessment of Taihu pollution status, and the knowledge of internal loading, phosphorus forms, and potential release will therefore be of significance for further study of mechanisms of eutrophication. In this study, the distribution and vertical variation of phosphorus forms in the sediment of 5 lake regions of Zhushan lake, Meiliang gulf, East lake, West sides and lake center of different trophic levels in Taihu Lake were studied, applying the standard measurement and test (SMT) procedure of phosphorus forms in the freshwater sediment. Moreover, the relation between phosphorus forms and internal release of phosphorus were discussed.The assessment results showed that the concentrations of total phosphorus in the sediment is coincided the corresponding trophic level of the overlying water. The results also showed that among the 5 lake regions of different trophic levels in Taihu Lake, Meiliang gulf, Zhushan lake and West sides were meso-eutrophic, East lake and lake center were eutrohic.The results showed that the total sedimentary phosphorus ranged from 300.93 mg/kg to 1018.48mg/kg. The total phosphorus consisted mainly of NaOH-P, OP and HCl-P. The inorganic phosphorus consisted mainly of NaOH-P and HCl-P. The total sedimentary phosphorus was highly correlated to other phosphorus forms. The dominant pool of phosphorus is the inorganic form, While IP was significantly correlated to NaOH-P.Great space diversity of phosphorus forms of sediment in Lake Taihu is observed. While the discrepancy of active species is greater than the inert ones. Generally speaking, the concentrations of NaOH-P and OP in the meso-eutrophic lake regions were higher than those in eutrohic areas. The concentrations of NaOH-P and OP were ranging from 147.37 mg/kg to 724.87mg/kg. The potential phosphorus loading provide favorable condition for algal uptake.