沙颍河表层沉积物中氮与重金属的分布特征及污染评价

为揭示沙颍河沉积物中氮及重金属的分布和污染特征,于2015年6—9月采集了沙颍河干支流主要站点的表层沉积物及上覆水样品,分析了其中氮的赋存形态和重金属的分布,探讨了水体-沉积物氮的转化机制及重金属的来源。结果表明:沙颍河表层沉积物中NO-3-N、NH+4-N、ON(有机氮)和TN的质量比分别为21.47~53.60 mg/kg、1.702 3~3.066 1 mg/kg、1 050~2 390 mg/kg和1 071~2 488 mg/kg,ON占TN的97.17%以上;表层沉积物中Cd、Cu、Zn和As质量比分别为1.583~3.533 mg/kg、21.98~64.60 mg/kg、148.5~165.5 mg/kg和1.527~2.416 mg/kg。Pearson相关性分析表明:表层沉积物中氮主要存在于有机物中,表层沉积物释放NH+4-N已经成为影响沙颍河水体NH+4-N浓度的一个重要因素;沙颍河大部分站点的表层沉积物有机指数和ON分别处于Ⅱ、Ⅳ级,有机碳污染较轻,ON污染严重;潜在生态评价中重金属Cd已经达到了很强-极强的污染程度,其余重金属则处于轻微污染水平;重金属潜在生态风险指数IR显示沙颍河表层沉积物重金属潜在风险已经到了很强-极强的水平,其中Cd对IR的贡献达97.22%。

Characterization and ecological risk assessment of nitrogen and heavy metal pollution in surface sediments of Shaying River

To assessment pollution of heavy metal and nitrogen in surface sediments of the Shaying River, sampling had been conducted during the period from June to September of 2015. The nitrogen occurrence characteristics and its transformation mechanism in surface sediments of the Shaying River were studied, as well as the distribution of heavy metal. Results showed that the contents of NO^-₃-N, NH⁺₄-N, organic nitrogen(ON)and total nitrogen(TN)in sediment were 21. 47~53. 60 mg/kg, 1. 702 3~3. 066 1 mg/kg, 1 050~2 390 mg/kg and 1 071~2 488 mg/kg, respectively, and ON accounted for 97. 17% of TN. While the contents of Cd, Cu, Zn, and As were 1. 583~3. 533 mg/kg, 21. 98~64. 60 mg/kg, 148. 5~165. 5 mg/kg and 1. 527~2. 416 mg/kg, separately. Pearson correlation analysis showed nitrogen in surface sediments were mainly existed in organic matter, while sediment could be an important source to the NH⁺₄ in the water body. Organic index and organic nitrogen of sediments, fell into the level II and the level IV, respectively, implying light organic carbon pollution but serious nitrogen pollution in the sediments. The potential ecological risk(I_R)of heavy metals showed that potential ecological risk of heavy metals has reached very high potential ecological risks, in which the contribution of Cd to I_R was about 97. 22%.