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不同性质农田土壤中铜的可提取性与生物有效性及毒性
朱 侠1, 李连祯1, 涂 晨1, 骆永明2
1.中国科学院海岸带环境过程与生态修复重点实验室(烟台海岸带研究所);2.中国科学院大学
摘要:
以重金属总量为基础的土壤环境质量标准已不适用于当前土壤管理的需求,基于重金属生物有效性的生态风险评估和环境阈值研究对土壤重金属环境质量标准的修订具有重要的指导意义。本研究选取黑土、潮褐土和脱潜水稻土3种不同性质的农田土壤,开展模拟铜(Cu)污染的生物毒性试验,采用HNO3、EDTA-Na2、NH4OAc和CaCl2 4种不同浸提能力的化学试剂进行土壤有效态Cu提取,探讨Cu可提取性与生物有效性及毒性的关系;并通过敏感性生态物种生菜和赤子爱胜蚓的Cu暴露试验,推导基于化学提取有效态的土壤Cu生态毒性阈值。研究结果表明:HNO3(41.4%)和EDTA-Na2(56.8%)对3种土壤中Cu的平均提取效率显著高于NH4OAc(0.12%)和CaCl2(8.70%)。CaCl2提取态Cu含量与生菜Cu富集量和毒性效应之间存在显著或极显著相关,HNO3提取态Cu含量则能很好地指示蚯蚓Cu富集量和30 d死亡率。不同生态受体毒性终点对土壤可提取态Cu的敏感性存在差异,选用物种最敏感指标推导3种土壤中Cu的有效态毒性阈值EC20和EC50,结果显示,基于不同化学提取态Cu含量的生菜毒性阈值EC20范围分别是90.5 ~ 170 mg/kg(HNO3)、103 ~ 195 mg/kg(EDTA-Na2)、3.97 ~ 20.1 mg/kg(NH4OAc)和0.21 ~ 8.68 mg/kg(CaCl2),EC50范围分别是110 ~ 188 mg/kg(HNO3)、119 ~ 230 mg/kg(EDTA-Na2)、5.69 ~ 32.2 mg/kg(NH4OAc)和0.26 ~ 9.62 mg/kg(CaCl2);基于不同化学提取态Cu含量的赤子爱胜蚓死亡率毒性阈值EC20范围分别是138 ~ 193 mg/kg(HNO3)、108 ~ 226 mg/kg(EDTA-Na2)、8.92 ~ 11.6 mg/kg(NH4OAc)和0.36 ~ 10.6 mg/kg(CaCl2),EC50范围分别是183 ~ 221 mg/kg(HNO3)、180 ~ 331 mg/kg(EDTA-Na2)、13.1 ~ 18.3 mg/kg(NH4OAc)和0.54 ~ 13.2 mg/kg(CaCl2)。研究结果可为我国农田土壤重金属有效态化学提取方法的比选与优化提供科学依据,同时对基于生物有效性的土壤重金属环境质量基准与标准的研究和制定具有重要意义。
关键词:  土壤    可提取性  生物有效性  生物毒性  阈值
DOI:10.13758/j.cnki.tr.2020.05.006
分类号:X825
基金项目:国家重点研发计划项目(2016YFD0800405、2016YFE0106400)和中国科学院STS项目(KFJ-STS-ZDTP-005)资助。
Extractability, Bioavailability and Toxicity of Cu in Farmland Soils with Different Properties
ZHU Xia1, LI Lianzhen1, TU Chen1, LUO Yongming2
1.Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences;2.University of Chinese Academy of Sciences
Abstract:
The environmental quality standards based on total contents of heavy metals can’t meet the requirements of current soil management, studies on risk assessment and toxicity threshold that considering the bioavailability of heavy metals have great significance for the revision of corresponding standards. In this study, three farmland soils with different properties, i.e, black soil, meadow cinnamon soil, unsubmerged paddy soil, were selected and biological toxicity tests were conducted by simulating Cu pollution, four chemical extractants with different extraction capacities, including HNO3, EDTA-Na2, NH4OAc and CaCl2, were used to extract bioavailable Cu, the relationship between Cu extractability, bioavailability and toxicity were analyzed, and the toxicity thresholds of Cu were deduced for lettuce and earthworm Eisenia foetida. The results showed that HNO3 (41.4%) and EDTA-Na2 (56.8%) had strong Cu extraction ability, but NH4OAc (0.12%) and CaCl2 (8.70%) had weak ability. Cu extracted by CaCl2 significantly correlated with Cu accumulated in lettuce, the toxic effect, and the acute mortality of earthworms, while Cu extracted by HNO3 significantly correlated with the chronic toxicity and Cu accumulated in earthworms. Based on the effective concentration of different extractable Cu, the deduced EC20 for lettuce ranged from 90.5 mg/kg to 170 mg/kg based on HNO3, 103 mg/kg to 195 mg/kg based on EDTA-Na2, 3.97 mg/kg to 20.1 mg/kg based on NH4OAc and 0.21 mg/kg to 8.68 mg/kg based on CaCl2, while the deduced EC20 for earthworm Eisenia foetida ranged from 138 mg/kg to 193 mg/kg based on HNO3, 108 mg/kg to 226 mg/kg based on EDTA-Na2, 8.92 mg/kg to 11.6 mg/kg based on NH4OAc and 0.36 mg/kg to 10.6 mg/kg based on CaCl2. The deduced EC50 for lettuce ranged from 110 mg/kg to 188 mg/kg based on HNO3, 119 mg/kg to 230 mg/kg based on EDTA-Na2, 5.69 mg/kg to 32.2 mg/kg based on NH4OAc and 0.26 mg/kg to 9.62 mg/kg based on CaCl2, while the deduced EC50 for earthworm Eisenia foetida ranged from 183 mg/kg to 221 mg/kg based on HNO3, 180 mg/kg to 331 mg/kg based on EDTA-Na2, 13.1 mg/kg to 18.3 mg/kg based on NH4OAc and 0.54 mg/kg to 13.2 mg/kg based on CaCl2. The results have great significance for the selection and optimization of effective extraction methods of heavy metals in soils and the revision of environmental quality standards based on heavy metals bioavailability.
Key words:  Soil  Cu  Extractability  Bioavailability  Toxicity  Threshold

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