植烟土壤重金属的有效性及影响因素研究

Availability of Heavy Metals and Its Influencing Factors in Tobacco Grown Soils

通过野外采样和室内分析,研究了植烟土壤中As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的有效态含量特征及其影响因素。结果表明,植烟土壤中8种重金属的有效态平均含量分别为0.92、0.075、0.75、1.62、0.004、1.89、1.14、1.94 mg·kg^-1;重金属有效态含量属于中等变异,变异系数在48.97%～95.64%之间,其中尤以有效Hg和Pb变化最为明显,分别为95.64%和90.56%,元素分布极为不均。相关分析表明有效As、Cd、Ni、Pb、Zn与8种元素中大部分元素都呈现较高的相关性,是伴随污染较多的元素,而有效Cr与其他元素的相关性很弱;主成分分析反映了土壤重金属有效性受工业和生活污染、农业污染和大气沉降污染影响较明显。通过分析有效态重金属与土壤pH和有机质的相关性发现,有效Cd、Pb与土壤pH呈极显著性负相关,有效Cr与pH呈显著性负相关;有效Cd、Pb与有机质呈极显著性正相关,有效As、Zn和Ni与有机质呈显著性正相关。

Research has showed that total contents of heavy metals in soils are not a good indicator of their eco-environmental impacts. Here availability of heavy metals including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in 440 tobacco grown soils was investigated and possible sources of heavy metals were also explored. The average available concentrations of heavy metals were 0.92, 0.075, 0.75, 1.62, 0.004, 1.89, 1.14 mg·kg^-1, and 1.94 mg·kg^-1 for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively. The coefficient of variation（CV）of heavy metal contents ranged from 48.97% to 95.64%, with the greatest variation for Hg and Pb（CV was 95.64% and 90.56%, respectively）. These data suggested that available Hg and Pb in soils were largely influenced by human activities, causing extremely uneven distribution. Each of available As,Cd, Ni, Pb, and Zn was highly correlated with most of these 8 elements, implying that they had common sources; while available Cr had very weak correlation with other metals, showing its unique sources. Principal component analysis showed that the availability of heavy metals was strongly influenced by industrial and agricultural sources as well as atmospheric deposition. In addition, soil properties influenced metal availability：soil pH was significantly negatively correlated with available Cd and Pb（P〈0.01）and available Cr（P〈0.05）; soil organic matter had significantly positive correlation with available Cd and Pb（P〈0.01）, and available As, Zn and Ni（P〈0.05）, implying that soil organic matter was an important factor influencing the availability of heavy metals.