南四湖微山湖区沉积物磷形态分布特征

Distribution of Phosphorus Species in the Sediment from Weishanhu District in Lake Nansihu

为了解南四湖污染底泥磷形态分布规律,对南四湖微山湖区0-25 cm沉积物分层进行了磷形态连续提取.结果表明,湖区沉积物中Ex-P、Al-P、Fe-P、Oc-P、Ca-P、De-P和Org-P平均含量分别为5.62、4.08、12.25、13.34、116.67、232.36和396.79mg/kg,不同形态磷含量次序为：Al—P〈Ex．P〈Fe—P〈Oc-P〈Ca-P〈De-P〈Org-P．沉积物中各形态磷含量在垂直方向上呈现明显的规律性，易交换态磷（Ex—P）、铁结合态磷（Fe—P）、闭蓄态磷（Oc-P）、有机磷（Org-P）含量随深度增加而逐渐降低，而铝结合态磷（Al-P）、钙结合态磷（Ca—P）、碎屑磷（De-P）含量则呈逐渐增加趋势．Suml（Ex—P、Al-P、Fe－P之和）与上覆水P04^3-浓度呈显著正相关，其中Fe—P与水体磷酸盐含量关系相对比较密切，其相关系数高达0．72．沉积物磷形态在空间分布上，Oc—P、Ca-P、De—P等惰性磷的差异性小于Ex—P、Al-P、Fe—P等潜在活性磷，Org—P介于二者之间．

In order to learn the phosphorus（P） species distribution in sediments of Lake Nansihu, 0-25 cm sediments from Weishanhu district in Lake Nansihu were analyzed with a sequential extraction method. The results show that： the average values of Ex-P, Al-P, Fe-P, Oc-P, Ca-P, De-P, Org-P in Weishanhu district sediments are 5.62 mg/kg, 4.08 mg/kg, 12.25 mg/kg, 13.34 mg/kg, 116.67 mg/kg, 232.36 mg/kg and 396.79 mg/kg respectively, and the rank order of P-fractionation for Lake Nansihu is Al-P 〈 Ex-P 〈 Fe-P 〈 Oc-P 〈 Ca-P 〈 De-P 〈 Org-P. The vertical phosphorous species distribution exhibits the obvious rule that exchangeable P（Ex-P）, Fe-bound P（Fe-P）, occluded P （Oc-P）, organic P（Org-P） value decrease with depth, while the values of Al-bound P（Al-P）, authigenic calcium bound P （A Ca-P）, detrital apatite P （De-P） increase. The Suml content （the sum of Ex-P, Al-P and Fe-P） in surficial sediments is remarkably positively correlated with the PO^3-4 concentration of overlaying water, to which Fe-P content contributes the most with the correlation index 0.72. In spatial phosphorous species distribution, the discrepancy of potential active species（Ex-P, Al-P and Fe-P） is greater than those inert ones（ Oc-P, Ca-P and De-P）, and Org-P is only second to those potential active species.