【作者】 张荣；

【导师】 张卫；

【作者基本信息】 华东理工大学 ， 环境科学与工程， 2016， 硕士

【摘要】 十溴联苯醚(BDE209)和铅(Pb)是电子垃圾拆解场地周边土壤中两种典型的污染物。目前,针对这两种物质生态毒理效应的评价多采用一次暴毒方式进行室内模拟研究。然而,实际环境中污染物通常是以逐步累积的方式进入土壤,因此需要针对重复暴毒模式的生物毒性开展研究。本论文以土壤微生物为研究对象,探究BDE209和Pb复合胁迫重复暴露条件下微生物的毒性响应及其对目标污染物的转化规律。研究结果将为电子垃圾拆解场地土壤BDE209和Pb生态风险评估和生物修复提供科学依据和技术支持。主要结论如下：(1)Pb单一及与BDE209的复合胁迫对脱氢酶和蔗糖酶均表现为促进作用,而对脲酶由先抑制再转为促进作用,污染物与酶活性间的剂量效应关系不明显。总体上看,重复暴毒对三种酶的毒性作用高于一次暴毒。两种污染物联合作用类型为脱氢酶和蔗糖酶中协同和拮抗作用共存,而脲酶以协同作用为主。(2)90 d培养过程中,两种暴毒方式处理下BDE209含量无明显变化,表明其在土壤中降解缓慢,而Pb主要以CAR-Pb 和FeMnOX-Pb两种形态存在,并在培养后期逐渐向RES-Pb转化。250mg kg-1 Pb重复暴毒土壤中,各形态百分比含量顺序为：FeMnOX-Pb> CAR-Pb>RES-Pb> OMB-Pb> EXCH-Pb,500 mg kg-1 Pb处理组对应为：CAR-Pb> FeMnOX-Pb> RES-Pb> OMB-Pb> EXCH-Pb,与一次暴毒组相比具有差异性。BDE209共存会影响土壤中Pb形态的分布。结合强度系数(IR)和再分配系数(Uts)在培养后期(>60 d)逐渐增大,重复和一次性暴毒相比,IR和Uts值呈现一定差异。皮尔逊相关性分析表明,IR值与三种土壤酶活性显著相关(p<0.05)。(3)不同暴毒方式和BDE209添加均会对土壤微生物多样性和群落组成产生影响。BDE209-Pb复合胁迫重复暴毒土壤中微生物多样性参数(Shannon)相较于一次处理显著下降(p<0.05)。100 mg kg-1 BDE209共存会导致重复暴毒土壤中微生物多样性和丰度显著降低(p<0.05)。门水平上优势菌群为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)和拟杆菌门(Bacteroidetes),属水平上主要优势类群为γ-变形菌纲(Proteobacteria)下的溶杆菌属(Lysobacter)和热单胞菌属(Thermomonas)。更多还原

【Abstract】 Decabromodiphenyl (BDE209) and lead (Pb) were two kinds of typical pollutants in soil around electric waste (e-waste) recycling sites (EWRSs). Recently, the study was conducted in the laboratory with one-off exposure treatments to determine the ecological effects of the two contaminants. However, in the real environment, pollutants usually gradually accumulated into soil, and it was essential to carry out the research to reveal the biotoxicity of repeated pollution events. In our study, the experiments were conducted to explore the toxic response of microorganisms after joint exposure of repeated BDE209 and Pb in soil as well as the transformation of target contaminants. Such observations would provide useful information for the ecological risk assessment and bioremediation of BDE209 and Pb at EWRSs. The results were as follows:(1) Pb alone or joint exposure with BDE209 both facilitated dehydrogenase and sucrase activity, but showed inhibited and then turned to stimulated effects on urease. The dose-effect relationship between soil contaminants and enzymes was not obvious. Compared to one-off exposure treatments, the enzymes were lower in repeated exposure groups. For dehydrogenase and sucrase, the interaction between BDE209 and Pb were antagonistic and synergistic, while for urease, synergistic role was dominant.(2) During the entire incubation, no obvious changes of BDE209 concentrations were observed in two exposure treatments, suggesting that it was hard to be degraded. Pb mainly existed in the form of CAR-Pb and FeMnOX-Pb, and with the incubation time extended, Pb gradually transformed to RES-Pb. In the 250 mg kg-1 Pb repeated treatments, the percentage of different fractions followed the order:FeMnOX-Pb> CAR-Pb> RES-Pb> OMB-Pb> EXCH-Pb. But in the 500 mg kg-1 Pb repeated treatments, the order was:CAR-Pb> FeMnOX-Pb> RES-Pb> OMB-Pb> EXCH-Pb. Compared to the repeated pollution events, the distribution of Pb speciation in one-off exposure groups was a little different. Moreover, the addition of BDE209 influenced the distribution of Pb speciation in soil. The parameter of Ir (Reduced Partition Index) and Uts (Whole-soil Redistribution Index) increased at the end of incubation period, and different exposure modes had an influence on Ir and Uts values. Besides, significant correlations between Ir and the soil enzymes were observed (p< 0.05).(3) Different Pb exposure modes and exogenous BDE209 input could influence soil microbial diversity and community composition. Sequence analysis showed that repetitive BDE209-Pb exposure caused significant lower microbial diversity indices (Shannon) compared to one-off treatments (p< 0.05).100 mg kg-1 BDE209 input elicited a significant reduction of microbial diversity and abundance in repeated exposure groups (p< 0.05). The results also illustrated that Proteobacteria, Acidobacteria and Bacteroidetes were predominant phyla. And the predominant genus were Lysobacter and Thermomonas (under Gammaproteobacteria level).更多还原