蚯蚓对土壤中重金属的富集作用研究

Effects of Earthworm Accumulation of Heavy Metals in Soil Matrix

通过向供试土壤中添加CuSO4、ZnSO4、Pb(Ac)2、HgCl2以模拟受污土壤,研究接种于其中的微小双胸蚯蚓对重金属的富集作用。以不加重金属盐类为对照,分别研究了不同培养时间和不同重金属浓度对富集量的影响。结果表明,蚯蚓对各种重金属的富集量随着培养时间的增加而变化,且对不同重金属最大富集量的出现时间也不相同。在第2周时蚯蚓对Cu、Pb富集量达到最大,而对Zn的富集量在第4周时达到最大。与Cu、Zn、Pb的富集量相比,蚯蚓对Hg没有明显的富集作用,且对Hg的最大富集量时间不明显。在其耐受浓度范围内,蚯蚓对重金属的富集量随着重金属浓度的增加而增加,且蚯蚓对重金属的吸收顺序为:Zn>Cu>Pb>Hg,说明了微小双胸蚯蚓对Cu、Zn、Pb、Hg4种元素有一定的忍耐和富集能力,但其对重金属的忍耐和富集能力是有选择性的,说明不同重金属表现出的毒性是不一样的。研究结果初步推断,影响蚯蚓对重金属富集作用的主要原因可能是体内酶的作用,不同重金属可以从多方面干扰了动物机体内的生理生化功能。

The objective of this work was to investigate the effects of earthworm（Bimastus parvus ）on the accumulation of heavy metals in the contaminated soil by adding CuSO4, ZnSO4, Pb（Ac）2 and HgC12. Through the comparison between adding and without adding the heavy metal salts into soil for control, the influences of the different incubation time and different concentrations on accumulation of heavy metals were studied. The results showed that the accumulation of heavy metals in earthworm body varied with the increased incubation time when the maximum accumulation times were variously determined for the different heavy metals added. The maximum accumulation of copper and lead could reach the maximum for two weeks, but four weeks for zinc. However, accumulation of mercury, in comparison with Cu, Zn and Pb, appeared to be unobvious and did not have the significant differences with time too. The results also proved that the accumulation of heavy metals in earthworm increased with the increase of heavy metal concentrations within its tolerance limitation. The heavy metals were absorbed by earthworm in priority following the order as Zn〉Cu〉Pb〉Hg. It certified that the earthworm had the capability of tolerance and accumulation to copper, zinc, lead and mercury, but these capabilities had the apparent selectivity, indicating that the different heavy metals showed a big difference in toxicity. On basis of the research results, it could be inferred that the main reason influencing the heavy metal accumulation might be the effect of enzyme in earthworm body. The different heavy metals could interfere with the physiological and biochemical functions of animals from various aspects.