草型湖区沉积物营养盐分布与污染评价

Distribution and Pollution Assessment of Nutrients in the Surface Sediments of a Macrophyte-Dominated Zone in Lake Taihu

为阐明太湖草型湖区表层沉积物营养盐的空间分布及其污染特征,测定了胥口湾60个表层沉积物样中的总氮(TN)、总磷(TP)、碱解氮(AN)、有效磷(AP)和有机质(OM)的含量,分析其污染水平与来源.结果表明,胥口湾表层沉积物中TN、TP、AN、AP和OM平均含量分别为1 027. 5、423. 2、46. 4、15. 3和17 096. 6 mg·kg-1,且在空间分布上均呈现出胥口湾东北部湖区高于其他湖区的特点.胥口湾表层沉积物中TN和TP单项评价指数(STN和STP)平均值分别为1. 75和0. 91,表明TN和TP分别处于中度和轻度污染状态;综合污染指数(FF)的平均值为1. 57,整体上处于中度污染状态.在有机指数和有机氮评价中,整体上处于清洁状态. C/N比值表明胥口湾表层沉积物中生物沉积的有机质主要来源为无纤维束植物和浮游植物.相关性分析表明,胥口湾表层沉积物中有机质与总氮具有同源性,但与总磷不具有同源性.

To clarify the spatial distribution and pollution status of nutrients in the surface sediments from a macrophyte-dominated zone in Lake Taihu,total nitrogen(TN),total phosphorus(TP),alkali nitrogen(AN),available phosphorus(AP),and organic matter(OM)were measured at 60 sampling sites in Xukou Bay.A pollution evaluation and source apportionment analysis of these nutrients was also carried out.The average contents of TN,TP,AN,AP,and OM in the surface sediments of Xukou Bay were 1 027.5,423.2,46.4,15.3,and 17 096.6 mg·kg-1,respectively,with the OM content being significantly higher in the northeast zone than in other areas of the bay.The average value of STNand STPwas 1.75 and 0.91,respectively,indicating that TN and TP represent moderate and mild levels of pollution,respectively.The average comprehensive pollution index(FF)was 1.57,indicated that the surface sediment was moderately polluted.The observed organic pollution index indicated that the surface sediments in Xukou Bay were generally clean.Based on C/N values,organic matter in the surface sediments is derived from the bio-deposition of non-fibrous plants and phytoplankton.Based on correlation analysis,OM and TN in the surface sediments of Xukou Bay are derived from the same source,while TP is derived from an alternative source.