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.
Sci Total Environ. 2019 May 10;664:975-983. doi: 10.1016/j.scitotenv.2019.02.054. Epub 2019 Feb 5.
This study investigated the effect of ageing on the bioavailability and toxicity of lead nitrate (Pb(NO)) and lead oxide (PbO) to Enchytraeus crypticus in LUFA 2.2 natural soil. The potworms were exposed after 2 weeks pre-incubation and after ageing the spiked soils for 3, 6, 12 and 18 months. Survival and reproduction after 21 d exposure were related to total, 0.01 M CaCl-extractable and porewater Pb concentrations in the soil and internal Pb concentrations in the surviving animals. Pb concentration in pore water showed little change during ageing for Pb(NO) but increased strongly for PbO-spiked soils. During ageing, toxicity of Pb(NO) did not change with LC50s and EC50s for the effect on enchytraeid survival and reproduction based on total soil Pb concentrations being constant at 523-619 and 89.8-99.4 mg Pb/kg dry soil, respectively. Toxicity of PbO, however, increased with LC50s and EC50s decreasing from 4830 to 1889 mg Pb/kg dry soil and from 151 to 97.5 mg Pb/kg dry soil, respectively. When related to internal Pb concentrations LC50s did not differ for both Pb forms at different ageing periods and were 73.4-78.7 mg Pb/kg dry body wt. Survival was better explained from internal Pb concentrations in the worms than from total or available Pb concentrations in the soil. Reproduction toxicity (EC50s) and Pb uptake in the worms however, were better explained from 0.01 M CaCl-extractable Pb concentrations in the soil. The latter finding could provide a scientific basis for the ecological risk assessment of contaminated soils and the derivation of soil quality standards based on extractable concentrations.
本研究调查了老化对硝酸铅（Pb(NO₃)₂）和氧化铅（PbO）在 LUFA 2.2 天然土壤中对穴居颤蚓（Enchytraeus crypticus）生物有效性和毒性的影响。在预孵育 2 周后，将这些穴居颤蚓暴露于受污染的土壤中，并在老化处理 3、6、12 和 18 个月后进行分析。暴露 21 天后，动物的存活率和繁殖率与土壤中总铅、0.01 M CaCl 可提取态铅和孔隙水中的铅浓度以及存活动物体内的内铅浓度相关。在老化过程中，Pb(NO₃)₂的孔隙水中的铅浓度变化不大，但对于 PbO 污染土壤，其浓度增加显著。在老化过程中，基于总土壤铅浓度的 LC₅₀和 EC₅₀（分别为 523-619 和 89.8-99.4 mg Pb/kg 干土）对穴居颤蚓的存活率和繁殖率的影响保持不变，因此 Pb(NO₃)₂的毒性没有变化。然而，由于 LC₅₀和 EC₅₀分别从 4830 降至 1889 mg Pb/kg 干土和从 151 降至 97.5 mg Pb/kg 干土，因此 PbO 的毒性增加。当与体内的铅浓度相关时，两种形式的铅在不同老化期的 LC₅₀没有差异，分别为 73.4-78.7 mg Pb/kg 干体重。与土壤中总铅或可利用铅浓度相比，动物体内的铅浓度能更好地解释其存活率。然而，繁殖毒性（EC₅₀）和蚯蚓体内的铅吸收量与土壤中 0.01 M CaCl 可提取态铅浓度的关系更好。这一发现为污染土壤的生态风险评估以及基于可提取浓度制定土壤质量标准提供了科学依据。
