澳门城市垃圾焚烧底灰的重金属淋溶及其遗传毒性评价

应用美国国家环境保护局推荐的毒性特性溶出程序(toxicitycharacteristicleachingprocedure,TCLP),以及ICP-MS和ICP-AES技术研究了澳门城市垃圾焚烧底灰中重金属的淋溶,并结合蚕豆根尖微核试验评价了其潜在的生态与健康风险.结果显示,该底灰淋溶出来的重金属元素:铝(Al)、锰(Mn)、钴(Co)和汞(Hg)的浓度低于0.01mg·L-1,铁(Fe)、铜(Cu)和钼(Mo)的浓度低于0.1mg·L-1,而铬(Cr)、锌(Zn)、硒(Se)、锶(Sr)、钡(Ba)和铯(Cs)的浓度在0.11mg·L-1￣2.19mg·L-1之间.需要注意的是淋溶液中铅(Pb)的浓度异常高,最高可达19.06mg·L-1,超过了美国相关标准的上限(5mg·L-1);对比不同条件下底灰中重金属的淋溶情况,表明溶解作用和淋溶液的pH值是影响其淋溶的2个重要因素.蚕豆根尖微核试验显示各淋溶液处理组根尖细胞微核率明显升高,与阴性对照组相比具有显著性差异(p<0.05),表明各淋溶液具有遗传毒性;随着淋溶液中重金属浓度的增加,蚕豆根尖细胞所表现出来的毒性效应增强,表明重金属是淋溶液具有遗传毒性的重要原因.

The Leaching Behavior and Genotoxic Assessment of Heavy Metals in the Municipal Solid Waste Incineration Bottom Ashes from Macao

In this study, toxicity characteristic leaching procedure(TCLP)was carried out on the municipal solid waste incineration bottom ashes from Macao. Heavy metals in the leachates were determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS)and Inductively Coupled Plasma Atomic Emission Spectrometry(ICP-AES), and genotoxicity of the leachates was also evaluated by micronucleus(MN) assay with Vicia faba root tip cells. The results showed that the concentrations of aluminium (Al), manganese (Mn), cobalt (Co), cadmium (Cd) and mercury (Hg) in the leachates were less than 0.01mg·L-1, and those of iron(Fe), copper(Cu) and molybdenum(Mo) were less than 0.1mg·L-1. The concentrations of chromium (Cr), zinc (Zn), selemium (Se), strontium (Sr), barium (Ba) and caesium (Cs) were between 0.11mg·L-1 and 2.19mg·L-1. Lead (Pb) concentrations, in particular, reached as high as 19.6mg·L-1, significantly exceeding the maximum concentration limit(5mg·L-1 for lead by TCLP). The different leaching behavior of heavy metals under different conditions implied that the pH values of leachates and the dissolution were two of the main factors that determine the leaching process in this study. Compared with the negative group, a significant increase of micronucleus frequencies was observed in the leachate-exposed groups(p<0.05). With the increase of heavy metals in the leachates, the toxic effects on the Vicia faba root tip cells increased, implying that heavy metals were the main factors causing the genotoxic effects.