三峡库区万州段不同类型消落带土壤磷形态贮存特征

三峡水库成库以来，消落带土壤磷流失已成为水体富营养化的重要来源。通过对三峡水库消落带万州段长江干流及回水区苎溪河和密溪沟土壤磷形态分析，研究了不同水力特征和人类活动对消落带土壤理化性质及土壤磷形态分布的影响。结果表明：万州段消落带土壤pH值、有效磷(A P)含量分布特征为长江干流>苎溪河>密溪沟，阳离子交换量(CEC)分布特征为苎溪河>长江干流>密溪沟，有机质(SOM)含量分布特征为密溪沟>苎溪河>长江干流，总氮(TN)含量分布特征为苎溪河>密溪沟>长江干流，总磷（TP）分布特征为密溪沟>长江干流>苎溪河。土壤水溶态磷（H2O P）、盐酸提取态磷（HCl P）、氢氧化钠提取态磷（NaOH P）、碳酸氢钠提取态磷（NaHCO3 P）、残渣态磷（Residual P）分布特征为：Residual P(65514 mg/kg)> H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)，以Residual P和H2O P为主，在干湿交替的条件下H2O P将继续向水体迁移。人类农业及旅游开发活动或将影响土壤理化性质进而影响保肥性能，土壤氢氧化钠提取态有机磷（NaOH Po）和碳酸氢钠提取态有机磷（NaHCO3 Po）所占比例大小顺序为长江干流>苎溪河>密溪沟。消落带土壤磷各形态中氢氧化钠提取态无机磷（NaOH Pi）、碳酸氢钠提取态无机磷（NaHCO3 Pi）、NaHCO3 Po、H2O P均与有A P存在极显著相关性，其来源具有同源性。密溪沟氮磷污染不同源，密溪沟有农村居民且开发旅游，人类生活废水是磷素的主要来源，而氮素主要来源于农业施肥的流失。

SOIL PHOSPHORUS SPECIES AND STORAGE CHARACTERISTICS OF DIFFERENT TYPES IN WATER FLUCTUATION ZONE OF THE WANZHOU SECTION OF THE THREE GORGES RESERVOIR

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