吉林中部黑土区重金属元素生态地球化学特征

基于吉林省中部黑土区地球化学调查数据,分析统计As、Cd、Cr、Cu、Ni、Zn 6种可造成重金属污染的元素在土壤--作物系统中的生态地球化学特征。通过吉林省部分地区土壤样品与玉米籽实样品采样,采用元素有效系数与元素累积系数的方法,计算出采样点的土壤重金属元素全量、有效量和玉米籽实含量特征,从而研究重金属元素生态地球化学特征。结果表明:(1)研究区土壤重金属元素全量虽然较吉林省土壤元素背景值增加明显,但土壤与玉米籽实均未达到污染状态。(2)重金属元素有效系数均值由小到大依次为As Cr Zn Cu Ni Cd,在研究区的空间分布差异性较大;玉米籽实积累系数均值由小到大依次为Cr As Ni Cd Cu Zn,在的空间分布差异性相对较小。(3)吉林省中部黑土区的玉米籽实重金属元素积累程度均较低,在未发生土壤重金属元素污染的清洁土壤中,Cu与Zn对于玉米植株来说,属于必需营养元素范畴;重金属元素中Cd的有效系数大,作物可食部分积累程度较高,应注意其预防与治理工作; As与Cr的有效系数较小,可能是导致其在玉米籽实中积累程度较低的主要影响因素之一; Ni在土壤中有效态转化程度较高,玉米籽实Ni吸收量相对较低。(4)多数重金属元素在玉米籽实中的累积程度与其在土壤中的有效系数呈正相关关系。

Ecological geochemistry characteristics of heavy metals in black soil region in central Jilin

Based on the geochemical survey data of the black soil region of central Jilin Province, the authors analyze the ecological geochemistry of six elements (As, Cd, Cr, Cu, Ni and Zn) that can cause heavy metal pollution in the soil crop system. By sampling the soil and corn seeds in parts of Jilin Province, using the method of element effective coefficient and element accumulation coefficient, the total heavy metal elements, effective amount and corn grain content were calculated to understand the ecological geochemistry of heavy metals. The research results indicated that:① the soil and corn seed samples were not polluted by heavy metals, even though the total concentration of soil heavy metals evidently exceeded the background value of Jilin Province. ② The metal bioavailable factors (MBFs) of As, Cr, Zn, Cu, Ni and Cd were in an ascending order, and varied greatly in spatial distribution. Other than that, the bioaccumulation factors (BAFs) of Cr, As, Ni, Cd, Cu, Zn were in an ascending order, and the BAFs mostly varied slightly in spatial distribution. ③ It is concluded that the heavy metals were mostly slightly accumulated by the corn seeds in studied area. Furthermore, the BAFs of Cu and Zn were relatively higher than the rest, indicating that Cu and Zn remained as soil nutrients when the soil was not polluted. Among all heavy metals, the MBF of Cd is the highest, meanwhile, it is also substantially accumulated in corn seeds. Thus, pollution prevention of soil Cd should be conducted preferentially. The MBFs of As and Cr were relatively low, which may then result in the less accumulation in corn seeds. The MBF of Ni was relatively high, however, the BAF was much lower when compared to other heavy metals. ④ The majority of MBFs of heavy metals were positively associated with the corresponding BAFs.