新型溴代阻燃剂十溴二苯乙烷和蚯蚓的相互作用机制

With the rapid development of E-wastes (electronic wastes) recycling industry, novel brominated flame retardants (NBFRs) released from the wastes processing have caused significant threat on soil health and biological safety at e-wastes recycling sites (EWRSs). Thus studies on their eco-toxicological effects and the associated remediation technique have become a hot topic. However, although NBFRs are present in many EWRSs, there has been nearly no study on their toxic effects on earthworms, and the evolution mechanism of remediation potential in soil. Aiming to modelling the real environmental exposure, this study will select decabromodiphenyl ethane (DBDPE) (i.e. typical NBFRs) as a target contaminant, and apply Eisenia fetida as an organism model; the soil samples will be exposed using the unique toxicant exposure mode, such as low dose and repetitive exposure trials (more appropriate for a real contaminated site). The indoor experiments will be conducted: (1) to observe the toxicological effects of DBDPE on Eisenia fetida from individual to molecular levels; and then screen the sensitive biomarkers for soil risk evaluation; (2) to explore the dynamics of DBDPE bioavailability and microbial community structure in soil based on 14C isotope tracer and DNA fingerprinting; and then investigate the evolution process of the remediation potential for both earthworms own and promoting soil microorganism that gradually adapting to the environmental pollution. The achievements of this research will comprehensively state the molecular mechanisms of the interaction between DBDPE and earthworm, and provide scientific evidences and technical supports for soil risk assessment and bioremediation at EWRSs.

伴随电子垃圾资源化快速发展，拆解过程中新型溴代阻燃剂（NBFRs）释放对土壤环境健康构成了严重威胁。本项目针对NBFRs与蚯蚓相互作用机制研究几乎空白的现状，选择十溴二苯乙烷（DBDPE）作为目标污染物，赤子爱胜蚓作为模式生物，首次采用低剂量重复暴露的独特染毒方式（更符合实际场地环境）针对蚯蚓毒性响应和修复潜能开展研究：（1）从个体到分子水平探究DBDPE对赤子爱胜蚓的毒性效应，筛选能用于污染场地风险评价的敏感生物标志物；（2）基于14C同位素示踪和DNA指纹图谱技术研究DBDPE生物可利用性和土著微生物功能菌群结构演变规律，探明蚯蚓自身及促进土著微生物形成修复潜能的进化过程。课题成果将揭示NBFRs典型代表DBDPE和蚯蚓相互作用的分子机制，为电子垃圾拆解场地土壤风险评价和生物修复提供科学依据和技术支持。

伴随电子垃圾资源化快速发展，拆解过程中新型溴代阻燃剂十溴二苯乙烷（DBDPE）释放对土壤环境健康构成了潜在威胁。本项目针对DBDPE与蚯蚓相互作用机制研究几乎空白的现状，主要围绕DBDPE暴露下模式生物赤子爱胜蚓毒性响应和修复潜能开展研究：（1）探究了DBDPE对蚯蚓的毒性效应，筛选出能用于污染场地风险评价的敏感生物标志物；（2）探究了DBDPE生物可利用性和土著微生物功能菌群结构演变规律，阐明了蚯蚓自身及促进土著微生物形成修复潜能的进化过程。主要研究结果如下：（1）DBDPE暴露28天未导致蚯蚓死亡，但对蚯蚓造成氧化应激压力与神经毒性，导致其组织损伤及体腔细胞凋亡。蚯蚓体内超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽转移酶（GST）活性降低，总抗氧化能力（T-AOC）和色素P450（CYP450）含量减少，乙酰胆碱酯酶、Na+/K+-ATP酶、Ca2+/Mg2+-ATP酶和羧酸盐酶活性提高，丙二醛（MDA）、活性氧（ROS）、钙和谷氨酸含量增加。（2）相较于表皮接触，肠道吸收是蚯蚓富集DBDPE的主要途径。富集因子（BAFs）值为0.028-0.213，清除速率常数（ke）为0.323-0.452（day-1），半衰期（t1/2）介于1.53-2.14之间。在蚯蚓体内发现了至少4种DBDPE脱溴产物。（3）与一步暴露相比，重复暴露提升了蚯蚓对DBDPE环境胁迫的抵抗能力与自身修复潜能，使DBDPE生物累积量减少了56.13%。（4）DBDPE降低了土壤-蚯蚓体系中微生物量碳（MBC）、代谢熵（qCO2）及脲酶活性，同时减少了土壤微生物群落多样性与γ变形菌纲丰度。（5）不同微塑料（ABS、PLA、PP和PE）共暴露促进了DBDPE在蚯蚓组织中的累积并加剧DBDPE对蚯蚓的组织损伤。（6）RT-qPCR及转录组学分析表明蚯蚓对DBDPE的分子应对机制包括激活线粒体电子运输、重组细胞骨架以及启动细胞自噬；一步暴露和重复暴露DBDPE导致不同的基因异常表达；MPs对DBDPE在蚯蚓体内的毒性效应影响机制包括干扰蚯蚓的溶酶体、吞噬体、化合物代谢、炎症及免疫系统等通路。项目研究成果揭示了DBDPE和蚯蚓相互作用的分子机制，将为电子垃圾拆解场地土壤风险评价和生物修复提供科学依据和技术支持。