模拟黑麦草根系有机酸参与下炼锌废渣对斑马鱼抗氧化酶和神经毒性的影响

Effects of zinc smelting residue after simulated addition of ryegrass root organic acids on antioxidant enzymes and neurotoxicity of zebrafish

为评价多金属矿山废渣堆场生态修复过程中,废渣在先锋修复植物根系分泌的机酸参与下浸出液对周边环境生物的影响.以斑马鱼(Danio rerio)为受试生物,通过模拟添加典型先锋植物(黑麦草)根系分泌的有机酸(草酸和酒石酸)处理贵州威宁土法炼锌废渣,以废渣浸出液对受试生物抗氧化酶和乙酰胆碱酯酶(AchE)的不同响应为评价指标,研究各处理组对斑马鱼抗氧化系统、神经系统及组织学的影响.结果表明,两种有机酸的参与均会不同程度地降低炼锌废渣浸出液的pH,并导致废渣释放出更多重金属;暴露于有机酸参与的废渣浸出液14 d后,受试生物组织中的抗氧化酶受到显著影响,并因无法克服长时间的氧化应激最终引起丙二醇(MDA)在组织中累积;有机酸参与下废渣浸出液对斑马鱼具有明显的神经毒性,长时间暴露后受试生物出现游动迟缓、呼吸慢和鳃盖张合频率降低的现象;鳃组织存在上皮细胞水肿、增生或脱落、鳃丝充血和鳃小片扭曲或断裂的现象,而肌肉组织中出现更多肌纤维核增大、固缩和碎裂的现象.综上,选用适生性和耐受性较强、根系发达且有机酸分泌量较大的先锋植物来修复多金属废渣场地将可能促进废渣中重金属的释放并引起环境生物抗氧化系统和神经系统的损伤.着眼于某些高适应高耐受劣境的先锋植物修复所带来快速复绿效果的同时,其根系分泌的有机酸可能带来的环境生态风险也应引起重视.

In order to evaluate the influence of waste residue leaching solution of waste residue after adding organic acid secreted by pioneer plant roots on surrounding environmental organisms in the process of ecological restoration of waste residue yard in polymetallic mines. In this paper,zebrafish(Danio rerio)was used as the subject. The organic acids(oxalic acid and tartaric acid)secreted by the roots of a typical pioneer plant(ryegrass)were used to treat the waste residue of native zinc smelting in Weining,Guizhou Province. And the effects of different treatments on the antioxidant system,nervous system,and histology of zebrafish were reflected by taking the different responses of the leachate to the tested biological antioxidant enzymes and acetylcholinesterase(AchE)as the evaluation index. The results showed that the participation of two kinds of organic acids can reduce the pH of the leaching solution of zinc smelting slag in different degrees,and more heavy metals can be released from the waste slag. Fourteen days after exposure to the waste residue leaching solution with the participation of organic acids,the antioxidant enzymes in the tested biological tissues were significantly affected,and the accumulation of propanediol(MDA)in the tissues was finally caused by the inability to overcome long-term oxidative stress. The leaching solution of waste residue with the participation of organic acid had obvious neurotoxicity to zebrafish. After long-term exposure,the tested organisms showed slow swimming,slow breathing,and decreased operculum opening frequency. There were edema,proliferation,or exfoliation of epithelial cells,hyperemia of gill filaments,and twisted or broken gill fragments in gill tissue,while more muscle fiber nuclei enlarged,pyknotic and fragmented in muscle tissue. Anyway,the heavy metals in the waste residue can be released and cause damage to the environmental biological antioxidant system and nervous system,through the selection of pioneer plants with strong adaptability,strong tolerance,a developed root system,and a large amount of organic acid secretion to repair the polymetallic waste site. While focusing on the rapid greening effect brought by some pioneer phytoremediation with high adaptability and high tolerance,attention should also be paid to the possible environmental and ecological risks caused by organic acids secreted by their roots.