干旱区绿洲土壤中重金属的形态分布及生物有效性研究

Experiments on speciation and bioavailability of selected heavy metals in arid oasis soil,northwest China

测定了Cd、Pb、Zn和Ni等重金属在不同处理土壤中的全量和各赋存形态,以及它们在盆栽试验油菜(Brassica cole)中的质量分数,并利用Pearson相关系数分析了该区土壤-油菜体系的生物有效性。结果表明,供试绿洲土壤原状土中,Cd、Pb、Zn和Ni均以稳定的残渣态形式存在;而在处理土壤中,重金属被钝化的量有限,Cd的存在形式主要以碳酸盐态为主,Pb、Zn和Ni则主要以铁锰氧化态为主。根据相关性分析,油菜根部和叶部的Ni质量分数均与土壤中Ni的各非残渣态分布系数有相关性,表明当土壤中Ni以非残渣态存在时,活动性Ni的质量分数较高,其被生物吸收利用的可能性也较大;油菜根部的Zn质量分数与土壤中Zn的碳酸盐结合态分布系数显著的正相关性;油菜各部位Cd和Pb的质量分数与土壤中Cd和Pb的各形态分布系数之间无显著相关关系。

Pot experiments were conducted on cole（Brassica cole）grown in amended soils treated with the four heavy metals：cad-mium,lead,zinc,and nickel.The metal contents and speciation distribution coefficients of the four heavy metals were investigated in amended soils.Accumulation of the selected heavy metals in the tissues of cole were also measured,and the bioavailability of the selected metals in soil to cole was analyzed by employing Pearson coefficients.The results showed that the metal content of the amended soils was higher than that of the unamended soil for all the selected heavy metals.The findings suggested that cadmium,lead,zinc,and nickel were not uniformly absorbed by cole in arid oasis soils.According to the results of the Pearson coefficients,by comparing accumulations of heavy metals in the tissues of cole and the speciation distribution coefficients of the heavy metals in soil,the exchangeable fractions of cadmium,lead,zinc and nickel and the carbonate bound fractions of zinc and nickel were the most bioavailability to cole.