铜污染对蚯蚓体重的影响与其铜富集特征

Effects of copper on earthworm in body weight and its copper accumulating characteristics

将简育湿润淋溶土和有机物料以体积分数1∶1混合,加入硫酸铜模拟成Cu2+0～200mg/kg的污染土壤。投入赤子爱胜蚓,以研究铜污染对蚯蚓生长和铜富集特征的影响。结果表明:蚯蚓体重与土壤铜污染浓度呈抛物线关系,低浓度的铜对蚯蚓生长有促进作用,Cu2+浓度>60mg/kg时对其生长有抑制作用,超过100mg/kg后铜污染浓度提高与污染接触时间延长均会加剧抑制程度,严重时出现负增长。蚯蚓表皮及肠道中铜含量与其铜吸收总量都随外源铜浓度的增加与污染暴露时间的延长而增加,且铜在肠道的积累速率大于表皮。土壤中铜浓度增加时肠道铜向表皮脂肪系统的运输增加,各处理肠道中铜含量与表皮的比值都随着土壤中铜浓度的增加呈下降趋势,但随着时间的推移有所提高。蚯蚓对污染土壤铜的有较强的富集能力,在Cu2+200mg/kg处理培养21d后,蚯蚓肠道的铜浓度是土壤环境铜浓度的2.65倍,铜富集总量达到最高值0.674毫克每10条。该结果对于探讨蚯蚓在铜污染土壤的适应机理,提高其对污染土壤的修复能力有重要意义。

The tolerant mechanism of earthworm to copper was studied in a mixed medium of soil and organic material with a volume ratio of 1：1. The medium was contaiminated with CuSO4·7 H2O and five levels of Cu^2＋ （0, 20, 60, 100,200） mg · kg^-1 were designed. Each treatment was replicated three times and 10 earthworms （Eisenia fetida） were added for each replicate. The effect of Cu on the weight of earthworm and its copper accumulation characteristicss in epidermis and the gut was studied. Result showed that ： the weight of earthworm had a parabola changing tendency with the increase of soil copper concentration. The growth of earthworm was enhanced by copper at low copper concentration and was restrained when Cu^2＋ concentration 〉 60mg/kg. If Cu^2＋ 〉 100 mg/kg, with the lengthening of the exposure period and the increasing of copper concentration, the restraining effect was more significant or even causing decline in body weight. Both of Cu content and Cu total accumulation in epidermis and gut were increased with the increasing of copper concentration and culturing time. The accumulating rate in gut was higher than that in epidermis. The increase of Cu concentration in medium could stimulate the transportation Cu from gut to epidermis sebum system. The ratio of Cu concentration in epidermis to that in gut was declined with the increase in copper dosage, but was risen by time. Earthworm had strong copper accumulation ability. The gut was 2.65 times the content of the environment when exposed in a medium with copper concentration of 200 mg/kg for 21 days, and the total accumulation reached to 0. 674 mg per lObar. The result should has an important significance in the research of the tolerant mechanism and the remediation ability of earthworm for polluted soil.