施用碳酸钙对土壤铅、镉、锌交换态含量及在大豆中累积分布的影响

Influence of Application CaCO_3 on Content of Pb,Cd,Zn Exchangeable in Soil and the Cumulative Distribution of Soybean Plants

在重金属复合污染的土壤中,通过施用不同水平的碳酸钙对土壤进行改良,研究土壤中Pb、Cd、Zn交换态含量的变化以及在大豆植株中的累积分布。结果表明:(1)在污染土壤中施用碳酸钙,能够降低土壤中Pb、Cd、Zn交换态含量,且随着碳酸钙施用量的增加,土壤中这3种重金属交换态含量呈明显降低趋势。在土壤中施用碳酸钙改善了大豆植株的生长状况,有效地抑制大豆植株对土壤Pb、Cd、Zn的吸收,从而减缓了重金属对大豆植株的毒害作用。(2)2.0 g/kg为碳酸钙的最佳施用量,能使大豆籽粒增产47.5%,籽粒中Pb含量降低73.0%,Cd含量降低53.8%,但在这个重金属污染矿区土壤中施用碳酸钙仍无法使籽粒中的重金属含量达到国家粮食卫生标准中Pb、Cd低于0.2 mg/kg的标准。

The purposes of these experiments were to study the effects of calcium carbonate addition on exchangeable Pb,Cd,Zn contents in the tested soils,to analyze and compare the effects of calcium carbonate addition on biomass of soybean plants and accumulation and distribution of heavy metals in each organs of soybean plants.The primary results of the experiments were as follows：（1） Application of calcium carbonate to contaminated soils reduced contents of exchangeable Pb,Cd,and Zn in the soils,and exchangeable Pb,Cd,and Zn contents in soils decreased obviously with increase in amount of calcium carbonate.The growth conditions of soybean plants were improved greatly,and the absorption of Pb,Cd,Zn from soils onto soybean plants were inhibited effectively due to addition of calcium carbonate,so as to reduce toxicity of soil heavy metals to soybean plants and biomass soybean increase greatly.（2） The optimal amount of calcium carbonate was 2.0 g/kg,which made yields of soybean seeds increased 47.5%,Pb and Cd contents in soybean seeds decreased 73.0% and 53.8%,respectively.Although application of calcium carbonate to the contaminated soils could reduce effectively heavy metal contents in soybean seeds,Pb and Cd contents in soybean seeds were still higher than the national standards in foods of 0.2 mg/kg.