北江流域横石河-翁江沿岸土壤重金属污染特征分析

采集了北江流域翁源县境内受大宝山矿区影响的横石河-翁江沿岸13个土壤剖面共49个土样,分析了河流沿岸土壤中重金属As、Cd、Cr、Cu、Fe、Mn、Ni、Pb和Zn的含量,讨论了土壤重金属含量的空间变化特征、污染程度以及潜在生态风险.结果表明:横石河沿岸(I区)土壤重金属污染较翁江沿岸(II区)严重,I区As、Cd、Cu、Zn的含量分别为26.6~430,1.99~11.9,31.7~765,63.5~646mg/kg; II区As、Cd、Cu、Zn的含量分别为4.16~51.3,0.830~4.67,3.99~103,17.6~83.7mg/kg;重金属含量差异分析显示,土壤重金属污染与污染源类型(大宝山矿山开采、农业、交通污染、生活垃圾等)、河水-地下水交互作用以及土壤理化性质(有机质含量、微粒组分)有关;As、Cu、Cd是研究区内主要的重金属污染元素,尤其以Cd污染最为严重,I区、II区Cd的地累积系数分别为6.13和4.84,属于极度污染和强-极度污染水平;土壤毒性单位评价结果显示,I区土壤(S23除外)剖面毒性单位(∑TU)均大于4,属于中毒性;II区土壤剖面∑TU普遍较低.

Characteristics analysis of heavy metal pollution in soil alongside Hengshihe and Wengjiang river in Beijiang Basin

To investigate the potential effects of heavy metal pollution in soil and water bodies, heavy metal content (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of 49 soil samples collected from 13soil profiles alongside river were analyzed. Spatial variation of heavy metal content was discussed and the potential ecological risks of polluted soil and water bodies were assessed as well. The results showed that the levels of As, Cd, Cu and Zn content were 26.6~430mg/kg, 1.99~11.9mg/kg, 31.7~765mg/kg and 63.5~646mg/kg in zone I which were significantly higher than that in zone II (4.16~51.3mg/kg, 0.830~4.67mg/kg, 3.99~103mg/kg and 17.6~83.7mg/kg). The spatial variation of heavy metal content was resulted from different pollution sources (mining activities in Dabaoshan Mine, agricultural activities, traffic load and domestic wastes, etc.), the interactions between contaminated river water and groundwater, and the physical-chemical properties of soils (soil organic matter and fine particles component).As, Cu and Cd were identified as major pollutant,with Cd which being the most serious pollutant The index of geo-accumulation (Igeo) for Cd in zone I and II were 6.13 and 4.84, respectively, which exceeded the severe pollution level. The toxic unit (∑TU) of all soil profiles in zone I was higher than 4 which was considered as moderately toxic.