Xia Xiaoqian, Lin Siyuan, Zhao Jun, Zhang Wei, Lin Kuangfei, Lu Qiang, Zhou Bingsheng
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.
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.
Chemosphere. 2018 Feb;192:43-50. doi: 10.1016/j.chemosphere.2017.10.146. Epub 2017 Oct 26.
Nickel (Ni)-contamination impairs soil ecosystem, threatening human health. A laboratory simulation of Ni-polluted farmland soil study, in the presence or absence of earthworm, was carried out to investigate the toxic responses of soil microorganisms, including microbial biomass C (MBC), soil basal respiration (SBR), metabolic quotient (qCO), urease (UA) and dehydrogenase activities (DHA). Additionally, the variations of Ni bioavailability were also explored. Results manifested that MBC and SBR were stimulated at 50 and 100 mg·kg of Ni but inhibited by further increasing Ni level, showing a Hormesis effect. Earthworm input delayed the occurrence of a maximum SBR inhibition rate under the combined double-factors of time and dose. No specific effect of Ni concentration on the qCO was observed. UA was significantly suppressed at 800 mg·kg Ni (P < 0.05 or 0.01), whereas DHA was more sensitive and significantly inhibited throughout all the treatments (P < 0.01), indicating a pronounced dose-response relationship. The addition of earthworm facilitated all the biomarkers above. The time-dependent of dose-effect relationship (TDR) on MBC and SBR inhibition rates suggested that the peak responsiveness of microorganisms to Ni stress were approximate on the 21st day. The bioavailable form of per unit Ni concentration declined with time expanded and concentration increased, and the changeable process of the relative amount of bioavailability was mainly controlled by a physicochemical reactions.
镍（Ni）污染会损害土壤生态系统，威胁人类健康。开展了一项在有或没有蚯蚓存在的情况下对镍污染农田土壤进行的实验室模拟研究，以调查土壤微生物的毒性反应，包括微生物生物量碳（MBC）、土壤基础呼吸（SBR）、代谢商（qCO）、脲酶（UA）和脱氢酶活性（DHA）。此外，还探讨了镍生物有效性的变化。结果表明，在镍含量为50和100mg·kg时，MBC和SBR受到刺激，但随着镍含量进一步增加而受到抑制，呈现出毒物兴奋效应。蚯蚓的引入延迟了在时间和剂量双重因素作用下SBR最大抑制率的出现。未观察到镍浓度对qCO有特定影响。在镍含量为800mg·kg时，UA受到显著抑制（P<0.05或0.01），而DHA更敏感，在所有处理中均受到显著抑制（P<0.01），表明存在明显的剂量-反应关系。蚯蚓的添加促进了上述所有生物标志物的变化。MBC和SBR抑制率的剂量-效应关系的时间依赖性（TDR）表明，微生物对镍胁迫的峰值反应在第21天左右。单位镍浓度的生物可利用形式随时间延长和浓度增加而下降，生物有效性相对量的变化过程主要受物理化学反应控制。
