研究了在蚯蚓影响下Pb、Cd 添加量不同(Pb:500 ~1 700 μg·g^-1 ;Cd:1 ~30 μg·g^-1 )的土壤中Pb 和Cd 有效态及其含量的变化以及小白菜(Brassica chinensis L.)对土壤中Pb 和Cd 的富集和转移作用。结果显示,在蚯蚓的影响下,Pb 添加量为500 ~1 400 μg·g^-1 的土壤中酸提取态和可还原态Pb 含量显著提高,有效态Pb 总含量也随土壤中Pb 添加量的提高逐渐增加;Cd 添加量为5 ~20 μg·g^-1 的土壤中酸提取态Cd 含量显著提高,有效态Cd 总含量也随土壤中Cd 添加量的提高而逐渐增加;当土壤中Pb 和Cd 添加量分别达到1 700 和30 μg·g^-1 时,蚯蚓对Pb和Cd 基本无活化作用。在蚯蚓的影响下,小白菜地上部分Pb 含量显著提高,对Pb 的转移系数也均高于各自的对照,地上部分和地下部分对Pb 的富集系数分别为0. 037 ~0. 061 和0. 401 ~0. 628。在蚯蚓影响下,在Cd 添加量较低(1 ~5 μg·g^-1 )的土壤中小白菜地上部分和地下部分的Cd 含量以及对Cd 的富集系数均高于各自的对照;而在Cd 添加量较高(10 ~30 μg·g^-1 )的土壤中小白菜地上部分和地下部分的Cd 含量以及对Cd 的富集系数均低于各自的对照,并随土壤中Cd 添加量的提高逐渐降低;小白菜地上部分和地下部分对Cd 的富集系数分别为1. 196 ~11. 516 和1. 744 ~20. 425;各处理组小白菜对Cd 的转移系数与各自的对照差异不显著。研究结果显示,蚯蚓主要对土壤中酸提取态和可还原态Pb 以及酸提取态Cd 有活化作用,并且可促进Pb 由小白菜地下部分向地上部分的转移,但对Cd 的转移无明显促进作用;此外,小白菜对Pb 的富集作用不明显,但对Cd 有一定的富集能力,这种能力的大小与土壤Cd 含量有关。

As affected by earthworm, the changes of Pb and Cd available states and their contents in soil with different addition amount of Pb and Cd (Pb: 500-1 700 μg·g^-1; Cd: 1-30 μg·g^-1 ) were studied, and their enrichment and transfer abilities of Brassica chinensis L. to Pb and Cd were also researched. The results show that as affected by earthworm, contents of acid extractable Pb and reducible Pb in soil with addition amount of 500-1 400 μg·g-1 Pb are increased significantly, and total content of available Pb increases gradually with increasing of Pb addition amount in soil. The acid extractable Cd content enhances obviously in soil with addition amount of 5-20 μg·g^-1 Cd and total content of available Cd increases gradually with increasing of Cd addition amount in soil. While earthworm generally has no activation effect on Pb and Cd in soil with addition amount of 1 700 μg·g^-1 Pb or 30 μg·g^-1 Cd. As affected by earthworm, Pb content in above-ground part of B. chinensis enhances obviously and Pb transfer coefficients in treatment groups all are higher than those in control groups. And the Pb enrichment coefficient of above-ground and under-ground parts of B. chinensis is 0. 037-0. 061 and 0. 401-0. 628, respectively. As affected by earthworm, Cd content and its enrichment coefficient in above-ground and under-ground parts of B. chinensis are higher than those of control groups in soil with lower addition amount of Cd (1-5 μg·g^-1 ), while those are lower than those of control groups in soil with higher addition amount of Cd (10-30 μg·g^-1), and Cd enrichment coefficient gradually decreases with increasing of Cd addition amount. And Cd enrichment coefficient in above-ground and under-ground parts of B. chinensis is 1. 196-11. 516 and 1. 744-20. 425, respectively. There is no obvious difference in Cd transfer coefficients between the treatment and control groups. It is revealed that earthworm has an activation effect to acid extractable Pb, reducible Pb and acid extractable Cd in soil, and promotes Pb transfer from under-ground part to above-ground part of B. chinensis, but has no obvious promoting effect on Cd transfer. Moreover, B. chinensis has no obvious effect on Pb enrichment, while has a certain Cd enrichment capability which relates to Cd content in soil.