Liu Gao, Ling Siyuan, Zhan Xiuping, Lin Zhifen, Zhang Wei, Lin Kuangfei
State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Shanghai Agricultural Extension and Service Center, Shanghai, 201103, China.
Chemosphere. 2017 Apr;173:227-234. doi: 10.1016/j.chemosphere.2017.01.022. Epub 2017 Jan 4.
Heavy metals usually cause great damage to soil ecosystem. Lead (Pb) was chosen as a research object in the present study. Here repeated exposure of Pb was designed for the soil artificially contaminated. A laboratory study was conducted to determine the changes in the Pb availability and biological activity in the presence of earthworm, and the risk assessment code (RAC) was applied to evaluate the remediated soil. Results demonstrated that Pb gradually transformed to more stable fractions (OMB- and FeMnOX-Pb) under microbial action, indicating the risk level of Pb was declined. On the other hand, Pb also caused the inhibition of soil respiration and microbial biomass, and the higher the concentration of Pb, the stronger the inhibition; While in the presence of earthworm, it could absorb Pb and facilitate microbial activity, reflected the decrease of Pb content and the increase of respiration intensity in soil, as well as microbial biomass. Additionally, a good dose-response relationship between EXCH-Pb content and respiration intensity might provide a basis for ecological risk assessment.
重金属通常会对土壤生态系统造成巨大破坏。本研究选取铅（Pb）作为研究对象。在此，针对人工污染土壤设计了铅的重复暴露实验。开展了一项实验室研究，以确定在蚯蚓存在的情况下铅的有效性和生物活性的变化，并应用风险评估代码（RAC）对修复后的土壤进行评估。结果表明，在微生物作用下，铅逐渐转化为更稳定的形态（有机结合态铅和铁锰氧化物结合态铅），这表明铅的风险水平有所下降。另一方面，铅也会抑制土壤呼吸和微生物生物量，铅浓度越高，抑制作用越强；而在有蚯蚓存在的情况下，蚯蚓能够吸收铅并促进微生物活性，这表现为土壤中铅含量降低、呼吸强度增加以及微生物生物量增加。此外，交换态铅含量与呼吸强度之间良好的剂量反应关系可能为生态风险评估提供依据。
