改性纳米碳黑修复镉污染土壤对蚯蚓的毒理效应

Toxicological effects of modified nano-carbon black on earthworms in Cd-contaminated soil

为评估改性纳米碳黑(modified nano-carbon black,MCB)应用于镉(Cd)污染土壤修复对蚯蚓的毒理效应,通过土壤培养试验和体外毒性试验比较纳米碳黑(nano-carbon black,CB)与MCB、Cd与MCB+Cd/MCB-Cd处理对蚯蚓个体存活率、生理生化指标、体腔细胞存活率和DNA损伤的差异.结果显示:(1)CB本身对蚯蚓个体及体腔细胞毒性较小.(2)与CB相比,施加1.5%MCB显著促进了蚯蚓体内过氧化氢酶(CAT)活力,降低了还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)比值(P<0.05),且100 mg/L MCB悬浮液比CB悬浮液对体腔细胞的DNA损伤程度更大.(3)土壤Cd含量为5.31 mg/kg时对蚯蚓个体存活率和CAT活力无显著影响,显著增加了乳酸脱氢酶(LDH)活力,降低了GSH/GSSG值(P<0.05).培养液Cd浓度为2.3 mg/L时对体腔细胞存活率和DNA损伤无显著影响.(4)MCB+Cd处理显著降低了土壤中Cd有效态含量(P<0.05),但没有显著降低蚯蚓对Cd的吸收;MCB+Cd处理与对照相比,蚯蚓个体存活率14 d显著下降32.1%(P<0.05),28 d下降51.9%,与单一Cd处理相比CAT活力显著抑制(P<0.05);MCBCd吸附产物处理组与对照组相比,体腔细胞存活率显著下降16.4%(P<0.05),与Cd处理相比体腔细胞DNA损伤程度显著增加(P<0.05).由于MCB对蚯蚓个体和体腔细胞的生理生化指标影响增强,并且Cd被MCB吸附后对蚯蚓体腔细胞存活率和DNA损伤影响加剧,因此需慎重选择MCB应用于土壤重金属污染修复.

To evaluate the toxicological effects of modified nano-carbon black(MCB)applied to Cd-contaminated soil on earthworms,earthworm(Eisenia fetida)soil incubation tests and in vitro cell toxicity tests were conducted.The effects of nano-carbon black(CB)and MCB on the survival and physiological and biochemical parameters of earthworms,and the survival and DNA damage to earthworm coelomocytes were compared.Additionally,the effects of Cd,MCB+Cd,and MCB-Cd treatments on these parameters were compared.The results showed that CB was less toxic than MCB to individuals and coelomocytes of earthworms,while the application of 1.5%MCB compared with CB significantly promoted catalase(CAT)activity and decreased the glutathione(GSH)/oxidized glutathione(GSSG)value(P<0.05).Moreover,the DNA damage to coelomocytes was significantly aggravated by 100 mg/L MCB in vitro(P<0.05).Cd appeared to have no significant effects on the survival and CAT activity of individual earthworms but significantly increased the lactic dehydrogenase(LDH)activity and decreased the GSH/GSSG value(P<0.05)at 5.31 mg/kg in soil.No significant effect of Cd in culture medium(2.9 mg/L)on coelomocytes was found.The available fraction of Cd in soil was significantly reduced(P<0.05)by MCB+Cd treatment,however the uptake of Cd by earthworms was not significantly reduced.This treatment also decreased the survival rate of earthworms by 32.1%(P<0.05)at 14 d and by 51.9%at 28 d,while significantly inhibiting CAT activity compared with that in the control.The MCB-Cd adsorption product significantly reduced the survival rate of coelomocytes by 16.4%(P<0.05)compared with that in the control and significantly(P<0.05)exacerbated coelomocyte DNA damage compared with that in the Cd treatment.Overall,the effects of MCB on the biochemical parameters of earthworms and coelomocytes were enhanced due to surface modification,and the effects of Cd on the coelomocyte survival rate and DNA damage were intensified following combination with MCB.It is therefore necessary to be cautious when choosing MCB for the remediation of heavy metal pollution in soil.