污泥农用对痕量元素在小麦－玉米轮作体系中的积累及转运的影响

利用田间试验初步研究了污泥农用对小麦、玉米大田作物及土壤环境影响以及污泥中痕量元素在土壤与植物可食部分之间转移规律.结果表明,施用污泥后,尤其是36t·hm~(-2)施用量时,土壤中Zn、Cu、Cd、Pb、As和Hg的含量均显著增加,但是施用污泥4.5至36 t·hm~(-2)后,除小麦籽粒中Zn、Cu含量和玉米籽粒中Zn、Cr含量显著增加外,其他痕量元素在小麦和玉米籽粒中的含量没有显著增加.作物籽粒中Zn含量与土壤中污泥施加量之间存在着显著的线性回归关系,土壤中增施1t·hm~(-2)污泥,小麦和玉米籽粒中Zn的含量分别增加0.570和0.118 mg·kg~(-1).小麦和玉米籽粒除Ni和Pb的富集系数相近外,对其他痕量元素而言,小麦籽粒的富集系数显著高于玉米籽粒.从痕量元素的累积速率和现行土壤环境质量标准考虑,北京污泥中Hg是优先考虑控制的元素,但是污泥中Hg对食品安全的影响还需要进行长期的大田实验研究.

Effects of Biosolid on the Accumulation and Transfer of Trace Elements in Soil-Wheat/Maize System

A field experiment was carried out to investigate the phytoavailability of trace elements in soils amended with biosolid and the transfer of trace elements in sludge from soil to the edible parts of plants. The results showed that land application of biosolid, especially at high rates, increased significantly the concentrations of Zn, Cu, Cd, Pb, As and Hg in soils. However, except for the increase in the concentra-tions of Zn and Cu in wheat grains and Zn and Cr in com grains, the concentrations of other trace elements in crop grains were not increased significantly by application of biosolid at the rates from 4.5 t·hm~(-2) to 36 t·hm~(-2). There was a significant linear relationship between the con-centrations of Zn in crop grains and the application rates of biosolid in soils; the concentrations of Zn in wheat and corn grains were increased by 0.57 and 0.118 mg·kg~(-1), respectively, when biosolid of 1 t·hm~(-2) was added to the soil. Except for similar accumulation factors between wheat and corn grains for Ni and Pb, for other trace elements the bioaccumulation factors of wheat grains were found to be higher than those of com grains. According to the accumulation rates of different trace elements and current soil environmental criteria, Hg in biosolid in Beijing was the element of high risk for soil environment quality. However, the effects of trace elements in biosolid in Beijing on food safety need to be investigated through further long-term field experiments. The results provided a scientific basis for developing a reasonable standard of biosolid application on agricultural land.