洪泽湖不同湖区表层沉积物中磷的形态和分布特征

采用七步连续提取法对洪泽湖9个不同湖区的表层沉积物中总磷(TP)、有机磷(OP)及各种无机磷(IP)形态进行了分析,结果表明,所测洪泽湖表层沉积物中TP含量范围为630.6～1403.4mg.kg-1,以IP为主,占TP含量的67.7%～83.6%;OP含量占TP含量的16.4%～32.3%。受淮河、濉河河水注入的影响,所研究沉积物中TP、IP和OP含量的最大值均出现在靠近入湖口的临淮乡区。IP分为6种形态磷,即交换态磷(Ex-P)、铝结合磷(Al-P)、铁结合磷(Fe-P)、闭蓄态磷(Oc-P)、自生钙磷(ACa-P)和碎屑钙磷(De-P),其中以De-P为主,其次是Fe-P,分别占TP的25.1%～37.3%和18%～35.5%,Ex-P、ACa-P和Al-P含量相对较低,Oc-P含量最低。Ex-P、Al-P和Fe-P作为洪泽湖表层沉积物中潜在的生物可利用磷,其总量占TP的22.5%～41.7%。相关分析表明,TP与IP之间存在着极显著的相关性,与OP的相关性较差,表明沉积物中TP的含量主要是由IP控制。

Chemical Forms and Distribution of Phosphorus in Surface Sediments of Lake Hongze

Total P(TP),organic P(OP) and different forms of inorganic P(IP) were analyzed by using the seven-step sequential extraction method in different sediments from Lake Hongze.Distribution characteristics of P in different sections and its impact on the natural water column were discussed.The results indicated that the contents of TP in all sediment samples range from 630.6~1403.4 mg·kg-1 and IP is its dominant portion,accounting for 67.7%~83.6% of TP.OP accounts for 16.4%~32.3% of TP.Their maxima all appear in Linhuai Township near the entrance of the Huai River and Sui River to Lake Hongze.IP includes six forms of phosphorus: exchangeable P(Ex-P),aluminum-bound P(Al-P),iron-bound P(Fe-P),occluded P(Oc-P),authigenic carbonate-bound P(Ca-P) and detrital P(De-P).De-P and Fe-P were found to be the major components of IP whose contents are 25.1%~37.3% and 18%~35.5% of TP,respectively.The contents of Ex-P,ACa-P and Al-P are all lower and those of Oc-P are lowest.Correlation analysis showed that TP is positively correlated with IP and poorly correlated with OP.IP strongly influences the contents of TP in sediments.