城市湖泊表层沉积物中PAHs的分布、来源及风险评价——以武汉市汤逊湖为例

Distribution, Source and Risk Assessment of PAHs in Surface Sediments of Urban Lakes: A Case Study of Tangxun Lake in Wuhan

作为中国最大的城中湖,汤逊湖受人类活动影响较大。为探究汤逊湖沉积物中多环芳烃(PAHs)污染情况,于2020年8月采集汤逊湖表层沉积物样品23个,使用GC-MS分析16种优控多环芳烃含量。结果表明:汤逊湖表层沉积物中PAHs含量介于219.13~3 917.36 ng·g^(-1)之间,平均含量715.58±809.80 ng·g^(-1),外湖污染程度高于内湖。沉积物中TOC含量与PAHs含量呈显著正相关,且与高环PAHs相关性最为显著。表层沉积物中PAHs以4~6环化合物为主,占∑PAHs总量的78.05%,单体成分以Fla、Phe、Pyr、BhiP和Chr等占比最高。与国内其他湖泊相比,汤逊湖整体处于中度污染水平。利用特征比值法和主成分-线性回归法(PCA-MLR)进行PAHs源解析,结果表明,汤逊湖表层沉积物中PAHs主要以燃烧源为主(石油燃烧、煤炭及生物生物质燃烧),少部分来自石油产品泄漏,其中交通排放源贡献率为62.62%,煤炭和天然气燃烧及石油泄漏混合源贡献率为37.38%。沉积物质量标准法(SQSs)的分析结果表明,研究区域沉积物PAHs整体呈较低生态风险水平,存在部分中等风险区域,有关部门需对中等污染区域加强监控和治理。

Tangxun Lake is the largest urban lake in China, which is greatly affected by human activities. In order to investigate the pollution status of polycyclic aromatic hydrocarbons(PAHs) in Tangxun Lake, a total of 23 surface sediment samples were collected in August 2020, and the contents of 16 PAHs were detected by GC-MS. The results showed that the concentration of PAHs in the surface sediments from Tangxun Lake ranged from 219.13 to 3917.36 ng·g^(-1), with a mean of 715.58±809.80 ng·g^(-1), the pollution degree of the outer lake was higher than that of the inner lake. The PAHs concentrations were significantly positively correlated with the total organic carbon(TOC) content in sediment, and the correlation between TOC and high molecular weight PAHs was more significant.The 4-6 rings PAHs were the main components in the surface sediment, accounting for 78.05% of the total PAHs, and Fla, Phe, Pyr, BghiP and Chr were the highest components. Compared with other domestic lakes, the PAHs pollution of Tongxun Lake was at a medium level. PAHs source analysis were carried out by a isomerratio method and principal component analysis and multiple linear regression(PCA-MLR), and the results showed that the PAHs were mainly originated from combustion sources(petroleum combustion, coal combustion and biomass combustion), and a small part of PAHs came from petroleum product leakage. The contribution ratio of traffic emission sources were 62.62%, and the contribution ratio of mixed sources of coal and natural gas combustion and oil leakage were 37.38%.The results of sediment quality standards(SQSs) showed that the overall level of ecological risk of PAHs in sediments of Tangxun lake was relatively low, and there were some areas with medium risk. The relevant departments should strengthen monitoring and treatment of the medium polluted areas.