Study Of The Relationship Between The Middle And Lower Reaches Of The Yangtze River Lake Sediment Physical And Chemical Nature Of Phosphorus And Its Form

Lake eutrophication is one of the most important environmental problems in our country, furthermore, the studies on phosphorus action in the interface of sediment-water is one of the key elements which helps find the mechanism of eutrophication. Among these, the studies on phosphorus forms and phosphorus adsorption of sediment are crucial aspects that can further reveal the mechanism of phosphorus action in the interface of sediment-water and supply direction and theoretical grounds to treatment and management of eutrophic shallow lakes in our country. This paper, distribution character of phosphorus forms in the sediment was analyzed, and isotherms for phosphorus sorption onto superficial sediments was studied under simulative condition.The concentrations of total phosphorous, cation exchange capacity and organic matter were 217.8 3337.2mg/kg, 8.61 25.28 meq/100g, 0.25% 7.38%, respectively; the main mineral compositions of sediments were quartz and albites; main clay minerals (<2μm) were montmorillonate, illite, chlorite and kaolinite. The common composition of the sediments was mainly made up of SiO₂ Al₂O₃ and TFe₂O₃, and their contents varied greatly as trophic levels change. There existed Positive relationships between Physical-Chemical characteristics and phosphorous concentrations in the sediments. As the concentrations of total phosphorous increased, the values of cation exchange capacity, organic matter and clay increased.The TP content in urban lake sediment was generally higher than that in big or middle lake sediment for example Tai hu. The IP was the major phosphorus species. In terms of the range of phosphorus forms content, Fe/Al-P>OP>Ca-P, to the range of percent content, Fe/Al-P>Ca-P>OP. IP in the sediment from the channel is mainly of Fe/Al-P, and IP in the sediment from dredged lake is mainly of Ca-P.The TP content is mainly under the influence of Fe/Al-P and OP. With the increase of TP content, Fe/Al-P percent in IP had a increasing tend. OP in the sediment was significantly and positively correlated to Fe/Al-P and Ca-P, but Fe/Al-P and Ca-P had a little correlation. Grain size had relatively big effect on TP and Ca-P content in the sediments; TN organic matter content have mainly effected OP and Fe/Al-P in the sediment; CEC have some effect on all of OP Fe/Al-P and Ca-P; among the major element, SiO₂ have good negative correlation with OP and Ca-P, TFe₂O₃ have the best positive correlation with Fe/Al-P OP, CaO have the best positive correlation with Ca-P...