千岛湖沉积物中碳、氮、磷的分布特征及污染评价

Distribution Characteristics and Pollution Assessment of Carbon,Nitrogen and Phosphorus in Sediments of Qiandao Lake

通过测定千岛湖柱状沉积物中有机质(OM)、总氮(TN)和总磷(TP)含量,分析其污染分布特征,并评价污染水平。结果表明,千岛湖沉积物中OM、TN、TP平均值分别为1.44%、1.86 mg/g、0.89 mg/g。空间分布差异明显,城区库湾、新安江干流沿线污染相对较重;垂直分布,OM、TN、TP整体上均从湖底由下而上呈逐步上升变化过程。相关性分析表明,该湖沉积物中OM、TN、TP具有较高的同源性,氮、磷多以有机形式存在。C/N值表明,该湖沉积物中有机质主要来自内源的水生生物分解。评价结果显示,综合污染指数范围为1.1~4.2,该湖整体上处于重度污染水平,TP污染重于TN;有机指数范围为0.04~0.52,整体上属于轻度污染水平。

In this paper,the contents of organic matter(OM),total nitrogen(TN)and total phosphorus(TP)in core sediments of Qiandao Lake were determined,the distribution characteristics were analyzed and the pollution status was evaluated.The results showed that the average contents of OM,TN and TP in sediments were 1.44%,1.86 mg/g and 0.89 mg/g,respectively.The spatial distribution differences were obvious.The pollution in urban bay area and along the main stream of Xinan River was relatively severe.In terms of vertical distribution,the contents of OM,TN and TP gradually increased from the bottom to the top of the lake.Correlation analysis showed that OM,TN and TP in sediments had high homology.Nitrogen and phosphorus mostly existed in organic form.The ratio of C/N indicated that organic matter in sediments mainly derived from endogenous decomposition of aquatic organisms.The evaluation results showed that the comprehensive pollution index ranged from 1.1 to 4.2,indicating that the lake was heavily polluted on the whole.TP pollution was heavier than TN.The organic index ranged from 0.04 to 0.52,indicating a light pollution level on the whole.