扎龙湿地表层沉积物磷的赋存形态及空间分布特征

Phosphorus Forms and Its Spatial Distribution Characteristics in Surface Sediments of Zhalong Wetland

沉积物中不同形态的磷具有不同的地球化学行为和生物有效性,其含量和分布特征包含着许多环境地球化学信息。该文利用SMT法对扎龙湿地表层沉积物中总磷(TP)及各形态磷进行了分析,探讨其空间分布特征及控制因素。结果表明,扎龙湿地表层沉积物TP含量高,接近于富营养化严重的太湖和巢湖,主要分布于核心区和东北部;无机磷(IP)含量稍高于有机磷(OP),其分布特征都与TP相似。IP中的钙结合态磷(Ca-P)和铁铝结合态磷(Fe/Al-P)空间分布差异性较小,Ca-P含量占IP的59.2%。TP及各形态磷含量受粒度、有机质、pH及溶解氧等环境因子的影响,造成扎龙湿地水体富营养化的污染物质主要来自外源;但随着湿地盐碱化加重、生态环境破坏及植被覆盖度下降,沉积物内源磷的释放将成为扎龙湿地水体富营养化的重要来源,将直接加剧水体富营养化程度,尤其增加核心区水体富营养化的风险。

Different phosphorus forms have different geochemical behavior and bioavailability.Their contents and distributions contain much environmental geochemistry information.In this paper,total phosphorus（TP）,organic phosphorus（OP）,and different forms of inorganic phosphorus（IP） were analyzed by using the SMT（standards,measurements and testing harmonized protocol） method in the surface sediments of Zhalong Wetland.The spatial distribution characteristics of phosphorus forms in the surface sediments and its controlling factors were discussed.The results indicated that the contents of TP coincided with the heavy nutrition of Taihu and Chaohu.Its spatial distribution lied in the core and northeast of Zhalong Wetland.TP contained IP and OP,and the content of IP was a little more than OP.In addition,their distributions were similar with the distribution of TP.The phosphorus associated with calcium（Ca-P） was the major part of IP,which was about 59.2% of IP.Owing to high content of Ca in the north geology environmental background,the change of Ca-P spatial distribution was less than others.The grain size,organic matter,pH,dissolved oxygen（DO）,etc.,were the main controlling factors of phosphorus in sediments.From current data,it was shown that the pollutants which caused water eutrophication of Zhalong Wetland were mainly from outside.However,with the invasion of pollutants,the deterioration of ecology,and the decreasing of vegetation coverage,the P released by the sediments could be the major sources to cause water entrophication of Zhalong Wetland,especially for its core area.This research not only provides a theoretical evidence for forecasting the trophic status of the water in Zhalong Wetland,but also has great implications to the scientific management for local government.