Abstract:

Loss of soil phosphorus from  water fluctuation zone is a main influence factor of eutrophication of water body in the Three Gorges Reservoir.The species of phosphorus were analyzed in areas of main stream of the Yangze River，Zhuxi River and Mixi Valley in water fluctuation zone of the Wanzhou section of the Three Gorges Reservoir.The influence of different types of hydraulic characteristics and human activities on soil physicochemical property and phosphorus species distribution were discussed in this paper.The objects are to determine the content and distribution of phosphorus species in Water Fluctuation Zone and discuss the influence of hydraulic characteristics and human activities on phosphorus species,and to estimate the probability of phosphorus lose in Water Fluctuation Zone of Wanzhou section.The results show that the distribution characteristics of pH value，available phosphorus (AP) are in an order of main stream of  Yangtze River>Zhuxi River>Mixi valley.The distribution characteristics of soil organic matter(SOM) ，total nitrogen (TN)，cation exchange capacity(CEC) and total phosphorus (TP) are in order of main stream of Yangze RiverH2OP (5177 mg/kg)>HClP(3999 mg/kg)> NaOHP(2588 mg/kg)>NaHCO3P(2224 mg/kg).The residualP and H2OP are the main phosphorus species.The content ranges are 42421-1 22642 mg/kg and 3138-7321 mg/kg，respectively.During the exchange soil condition of wet and dry，the H2OP will continue transferring to the water of Yangtze River.Agriculture and tourism development activities of human have affected the soil physicochemical property and fertilizer conservation.The proportion of organic phosphorus in NaOHP and NaHCO3P is in an order of main stream of Yangtze River>Zhuxi River>Mixi valley.There are significant correlations among NaOHPi,NaHCO3Pi,NaHCO3Po,H2OP and AP，since they share a same origin.Nitrogen and phosphorus pollution come from different sources in Mixi Valley.The main source of phosphorus and nitrogen pollution are domestic wastewater and agricultural fertilizer loss，respectively