三门湾沿岸土壤潜在有毒元素分布、来源及环境风险评价

土壤中潜在有毒元素(PTEs)易通过食物链的累积对人体健康构成严重威胁，探究其浓度对于生态环境安全具有重要意义。为查明浙江三门湾沿岸土壤中PTEs含量、分布特征及主要来源，在三门湾沿岸4个小流域采集了36个站位土壤样品，进行了土壤黏土矿物、土壤酸碱度、10种PTEs及Si、Al、Fe和TOC含量分析。利用相关性和主成分分析进行了来源分析，并采用《土壤环境质量》（GB 15618—2018）、富集因子（EF）、内梅罗污染指数（PI）及潜在生态风险污染指数（RI）评价模型进行了环境风险评价。结果表明，不同地貌单元土壤黏土矿物组成差异明显，山间平原土壤高岭石和绿泥石占比相对高(平均值>30%)，海积平原伊利石占比相对高（>60%）。山间平原土壤主要为原地母岩风化成壤，而海积平原区土壤主要为历史时期长江来源沉积物改造而成。土壤PTEs整体上呈现流域上游向下游增加的分布趋势。平均富集程度依次为Hg>Cd>Sb>As>Pb>Ni>Cr>Co>Zn> Cu。Hg元素轻微富集、中等富集和中等严重富集站位占比分别为27.8%、2.8%和2.8%。Cd、Sb、As和Pb分别有13.9%、8.3%、8.3%和16.7%的站位为轻微富集。PI值显示，5.6%的站位为严重和重度污染。RI值显示，16.7%的站位处于中生态风险水平，其中Hg和Cd分别贡献了44.8%和25.9%。相关性及主成分分析表明，Cu、Zn、Cr、Ni、Co、As、Sb主要是自然来源，受到成土母质、土壤机械组成、土壤pH等因素的影响。Pb、Cd、Hg主要为工业、农业及交通等人类活动来源。

Distribution,sources and environmental risk assessment on potential toxic elements in soils along coast of Sanmen Bay

The accumulation of potential toxic elements (PTEs) in soil through the food chain poses a serious threat to human health. Therefore, it is important to investigate the concentration of PTEs in soil for ecological and environmental safety. To identify the content, distribution, and main sources of PTEs in soils along coast of Sanmen Bay, Zhejiang, soil samples were collected in 36 sites in four sub-basins along Sanmen Bay. The analyses of clay minerals, pH, 10 PTEs, Si, Al, Fe, and TOC in the soils were performed. Source analysis of PTEs was performed using correlation and principal component analysis. Assessment on environmental risk of PTEs based on the Soil Environmental Quality (China National Standard GB 15618—2018), Enrichment Factor (EF), Nemerow Pollution Index (PI), and Potential Ecological Risk Pollution Index (RI) was conducted. Results show that the clay mineral composition of soils in different geomorphic units varied significantly. In comparison, the proportions of kaolinite and chlorite in the intermontane plain soils were relatively high (>30% on average), and that of illite in the marine plain was relatively high (>60%). The intermontane plain soils are mainly from local weathered parent rocks, while the marine accumulation plain soils are mainly modified by sediment from the Changjiang (Yangtze) River during the historical period. The concentration of soil PTEs shows an increasing trend from upstream to downstream in all sub-basins. The order in average enrichment of PTEs from high to low was Hg, Cd, Sb, As, Pb, Ni, Cr, Co, Zn, and Cu. In addition, 27.8%, 2.8%, and 2.8% of the sites were in minor enrichment, moderate enrichment, and moderately-severe enrichment in Hg, respectively; 13.9%, 8.3%, 8.3%, and 16.7% of the sites were in minor enrichment in Cd, Sb, As, and Pb, respectively. PI values showed that 86.1%, 2.8%, and 2.8% of the sites were moderately polluted, heavily polluted, and severely polluted, respectively. RI values showed that 16.7% of the sites ranked in ecological grade of moderate risk, whose Hg and Cd were amounted to 44.8% and 25.9%, respectively. The correlation and principal component analysis suggested that Cu, Zn, Cr, Ni, Co, As, and Sb were mainly in natural origination from soil-forming parent rocks, soil mechanical composition, soil pH, etc. On the other hand, Pb, Cd, and Hg were mainly anthropogenic from activities of industry, agriculture, and transportation.