Department of Resources and Environment, Baotou Teachers' College, Inner Mongolia University of Science & Technology, Qingshan District, Baotou City, Inner Mongolia Autonomous Region, 014030, China; Department of Ecological Science, Faculty of Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
Department of Ecological Science, Faculty of Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
Chemosphere. 2018 Feb;193:412-420. doi: 10.1016/j.chemosphere.2017.11.040. Epub 2017 Nov 10.
This study determined the toxicity of lanthanum, one of the most commonly used rare earth elements (REEs), to five representative soil invertebrates after 3-4 weeks exposure. Toxicity was related to total, 0.01 M CaCl-extractable and porewater concentrations in the standard LUFA 2.2 soil, and for earthworms also to body concentrations. La sorption to LUFA 2.2 soil, estimated by relating total soil concentrations to CaCl-extractable or porewater concentrations seemed to reach saturation at >1000 mg La/kg dry soil. Isopod (Porcellio scaber) growth was the most sensitive endpoint, followed by earthworm (Eisenia andrei), enchytraeid (Enchytraeus crypticus), springtail (Folsomia candida) and oribatid mite (Oppia nitens) reproduction, with ECs of 312 (95% confidence interval: 5.6-619), 529 (295-762), 1010 ((>377 < 3133), 1220 (1180-1250) and 1500 (1250-1750) mg La/kg dry soil, respectively. ECs related to CaCl-extractable concentrations ranged between 1.3 (0.046-2.6) and 15.6 (5.6-25.7) mg La/kg dry soil, while porewater-based ECs were 3.5 (-) and 10.2 (-) mg/L for the springtails and mites, respectively. La uptake in the earthworms linearly increased with increasing exposure concentration with bioaccumulation factors ranging between 0.04 and 0.53 (average ± SE: 0.24 ± 0.032). EC for effects on earthworm reproduction related to internal concentrations was 184 (61-301) mg La/kg dry body weight. A risk assessment based on the available toxicity for soil invertebrates, bacteria and plants resulted in an HC of approx. 50 mg La/kg dry soil, suggesting that La may affect soil ecosystems at concentrations slightly above natural background levels (6.6-50 mg La/kg dry soil) in non-polluted soils.
本研究在 3-4 周暴露后，确定了最常用的稀土元素（REEs）之一镧对五种代表性土壤无脊椎动物的毒性。毒性与标准 LUFA 2.2 土壤中的总浓度、0.01 M CaCl-可提取浓度和孔隙水浓度有关，对于蚯蚓，还与体内浓度有关。通过将土壤总浓度与 CaCl-可提取浓度或孔隙水浓度相关联，镧对 LUFA 2.2 土壤的吸附似乎在 >1000 mg La/kg 干土时达到饱和。等足目（Porcellio scaber）的生长是最敏感的终点，其次是蚯蚓（Eisenia andrei）、真蚓目（Enchytraeus crypticus）、弹尾目（Folsomia candida）和甲螨目（Oppia nitens）的繁殖，其 EC50 值分别为 312（95%置信区间：5.6-619）、529（295-762）、1010（>377 <3133）、1220（1180-1250）和 1500（1250-1750）mg La/kg 干土。与 CaCl-可提取浓度相关的 EC50 值范围为 1.3（0.046-2.6）和 15.6（5.6-25.7）mg La/kg 干土，而基于孔隙水的 EC50 值分别为 3.5（-）和 10.2（-）mg/L，用于弹尾目和甲螨目。蚯蚓体内镧的摄取量随暴露浓度的增加呈线性增加，生物积累因子在 0.04 至 0.53 之间（平均值±SE：0.24±0.032）。与蚯蚓体内浓度相关的对蚯蚓繁殖的影响的 EC50 值为 184（61-301）mg La/kg 干体重。基于土壤无脊椎动物、细菌和植物的现有毒性进行的风险评估得出 HC 值约为 50 mg La/kg 干土，这表明在无污染土壤中，镧的浓度略高于自然背景水平（6.6-50 mg La/kg 干土）时，可能会影响土壤生态系统。
