泸沽湖大草海湖滨带表层土壤的多环芳烃污染状况及其生态风险评价

Pollution Status and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Soils in the Lakeshore of Dacaohai of Lugu Lake, Sichuan Province

于2019年3月12~13日,在四川省泸沽湖大草海湖滨带的41处采样地中,采集表层(0~20 cm深度)土壤样品,分析测试土样的多环芳烃含量;根据多环芳烃含量的分级标准,确定表层土壤的多环芳烃污染状况,并评价其生态风险。研究结果表明,菜地、果园、林地、耕地和季节性湿草甸表层土壤中的16种多环芳烃质量比之和分别为1 565.98 ng/g、1 463.28 ng/g、676.93 ng/g、591.66 ng/g和583.03 ng/g,菜地表层土壤中多环芳烃含量相对最高;大部分采样地表层土壤属于多环芳烃轻微污染,分布在道路边、人流量较大的地方、居民住宅旁的菜地和污染沟渠附近的采样地表层土壤属中度和重度多环芳烃污染;采样地表层土壤中的多环芳烃来源主要以生物质能源燃烧和交通源为主;多环芳烃对儿童的致癌风险指数小于10^-6,处于安全范围,成人通过皮肤接触途径造成的多环芳烃致癌风险指数最大值和总致癌风险指数都大于10^-6,故成人存在致癌风险。

In order to investigate polycyclic aromatic hydrocarbons contamination and ecological risks of surface soil(0-20 cm depth) in the lakeshore of Dacaohai of Lugu Lake in the Liangshan Autonomous Prefecture of Sichuan province, 41 sampling sites were set, and the soil samples were collected on March 12-13, 2019, and contents of polycyclic aromatic hydrocarbons were determined using high performance liquid chromatographer. According to the classification standard of polycyclic aromatic hydrocarbons content, the pollution condition of 16 kinds of polycyclic aromatic hydrocarbons in the surface soil was defined and ecological risks were evaluated. The results showed that the total contents of the 16 kinds of polycyclic aromatic hydrocarbons in the surface soil of the vegetable patches, the fruit orcharding, artificial forest land,corn fields and seasonal lakes were 1 565.98 ng/g, 1 463.28 ng/g, 676.93 ng/g, 591.66 ng/g and 583.03 ng/g,respectively. The contents of 16 kinds of polycyclic aromatic hydrocarbons in the surface soil of vegetable patches were the highest. In the study, in accordance of total contents of polycyclic aromatic hydrocarbons,56.10% of the soil samples were little contaminated, 17.07% moderately contaminated and 26.83% heavily contaminated. Moderately and heavily contaminated sampling sites were mainly located near the roadside, the places of large flow of people, vegetable patches near the house and lands near the polluted ditches or streams.Diagnostic ratios showed that the main possible source of polycyclic aromatic hydrocarbons in the surface soil in the lakeshore of Dacaohai could be combustion of biomass burning emissions(eg: coal, fire woods) and traffic emissions(such as oil spills, oil burning). The cancer risks values were less than 10^-6 for children,indicating no potential cancer risk. In addition, the maximum cancer risk value and the total cancer risk value of polycyclic aromatic hydrocarbons were more than 10^-6 though the dermal contact pathway for the adults,respectively, and showed that there were potential cancer risks for the adults.