长潭水库水体沉积物营养盐分布特征及其污染评价

Distribution Characteristics of Nutrients and Pollution Status Evaluation of Sediments in Changtan Reservoir

探究长潭水库库区沉积物中碳(C)、氮(N)、磷(P)含量特征及其污染状况,可为区域水环境质量提升提供理论依据。研究于2021年9月在水库中心区及8条入库支流断面设置28个采样点,对表层沉积物中的总有机碳(TOC)、总氮(TN)、总磷(TP)含量进行测定,并采用单因子指数法、综合污染指数法和有机污染指数法对库区污染状况进行了评价。结果表明:库区表层沉积物中TOC,TN和TP含量分别为(13.67±3.81) g/kg,(1.46±0.37) g/kg,(0.43±0.17) g/kg;其中,以柔极溪(RJR)含量较高,其TOC含量显著高于库中心区与其余入库支流(p<0.05)。表层沉积物中C/N,C/P,N/P比值范围分别为7.72~15.07,15.28~63.20,1.66~6.26。由单因子指数法和综合污染指数法分析可知,整个库区水体沉积物TN污染严重,基本属于重度污染;有机氮评价结果进一步表明库区整体处于Ⅲ级污染水平(尚清洁),其中以库中心区和RJR污染较重,存在有机氮污染(等级为Ⅳ级)。长潭水库存在一定的内源污染,且以有机污染为主。未来应加强库区水体沉积物营养盐含量动态的监测研究。

The aim of this study is to investigate the characteristics of the contents of carbon(C), nitrogen(N) and phosphorus(P) in the sediments of Changtan Reservoir and the pollution status, thus to provide theoretical basis for the improvement of regional water environment quality. This study set up 28 sampling points within the reservoir in September 2021, which included 8 inlet tributary sections and the central area of the reservoir. The surface sediments were selected to measure the contents of total organic carbon(TOC), total nitrogen(TN), and total phosphorus(TP). Meanwhile, the pollution status of the reservoir was evaluated by single factor index method, integrated pollution index method, and organic pollution index method. Results showed that the contents of TOC, TN and TP in the surface sediments of the reservoir area were(13.67±3.81) g/kg,(1.46±0.37) g/kg, and(0.43±0.17) g/kg, respectively;specifically, the TOC content in RJR was significantly higher than that in other sampling sites(p<0.05);the C/N, C/P and N/P ratios in the surface sediments ranged from 7.72 to 15.07, 15.28 to 63.20, and 1.66 to 6.26, respectively;according to the single factor index and comprehensive pollution index, the whole reservoir was suffering from heavy TN pollution;the organic nitrogen index further indicated that the reservoir was at the levelⅢ, among which the central area and RJR were heavily polluted by organic nitrogen(level Ⅳ);there was a certain amount of endogenous pollution in Changtan Reservoir, mainly for the organic pollution. More attentions should be paid to the dynamics of nutrients in the sediments of Changtan Reservoir.