密云水库上游铁矿区重金属在胡敏酸中的分布特征研究

Distribution of Heavy Metals in Humic Acids of Iron Mine Soil in Upper Area of Miyun Reservoir, Beijing

以北京市密云水库上游铁矿区为研究对象,研究了不同深度(0~20 cm和20~40 cm)土壤样品和胡敏酸中重金属的分布特征以及重金属与胡敏酸之间的相关性。根据国际腐殖质协会提供的胡敏酸提取方法从土壤样品中提取胡敏酸,使用ICP-MS测定了土壤样品和胡敏酸中重金属V、Cr、Co、Ni、Cu、Zn、Cd和Pb的含量,并使用相关性分析法和富集因子法研究了重金属和胡敏酸之间的相互关系。结果表明:土壤样品中V、Cr、Co、Ni、Cu、Zn、Cd和Pb在0~20 cm的平均含量高于20~40 cm;胡敏酸中V、Co、Ni、Cu、Zn和Pb在0~20 cm的平均含量高于20~40 cm,Cr和Cd则相反。相关性分析表明V、Cr、Co、Ni、Cu、Cd和Pb的含量与有机质含量和胡敏酸含量均表现出显著相关性,V、Co、Cu、Cr、Ni和Zn的含量与胡敏酸和有机质含量之比(HA/OM)呈负相关。富集因子分析表明胡敏酸对V、Cr、Ni、Zn和Pb的结合能力不强,而对Cu元素的结合能力很强;0~20 cm的胡敏酸对V、Cr、Co、Ni、Cu、Zn和Pb的富集程度高于20~40 cm,Cd则在20~40 cm的胡敏酸中富集程度更高。

Interaction of heavy metals with humic acid(HA)in soils may affect their movement and bioavailability. Here we measured the concentrations of heavy metals in iron mine soils and humic acids extracted from the soils at the depth of 0 to 20 cm and 20 to 40 cm in the upper area of Miyun reservoir, Beijing. Humic acids were extracted with a method from International Humic Substance Society(IHSS). The concentrations of heavy metals and humic acids were determined by ICP-MS. The relationship between humic acids and heavy metals was analyzed by correlation analysis and enrichment factor analysis. The results show that the average concentrations of V, Cr, Co, Ni, Cu, Zn,Cd and Pb in the soils samples were higher at 0 to 20 cm than at 20 to 40 cm. The average concentrations of Cr and Cd in humic acids were lower at 0 to 20 cm than at 20 to 40 cm, but those for other metals were just opposite. Soil depth affected heavy metal association with humic acids. Significant positive correlations were found between V, Cr, Co, Ni, Cu, Cd, and Pb and organic matter and HA, while significant negative correlations existed between V, Co, Cu, Cr, Ni, and Zn and the ratio of HA to OM(HA/OM). The enrichment factor analysis showed that Cu had a greater affinity, but V, Cr, Ni, Zn and Pb a weaker affinity for humic acids. Compared to soils at 20 to 40 cm, V, Cr, Co, Ni, Cu, Zn and Pb had a stronger enrichment but Cd had a weaker accumulation in the humic acids of soils at 0 to 20 cm. These results indicate that soil humic acids from different depths have different metal accumulation characteristics.