Nie Jing, Pan Yuqiang, Shi Jing, Guo Yan, Yan Zengguang, Duan Xiaoli, Xu Meng
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Int J Environ Res Public Health. 2015 Nov 30;12(12):15075-87. doi: 10.3390/ijerph121214972.
In soil ecotoxicological studies, a toxic metal is usually added in the form of either an inorganic or organic salt with relatively high solubility. Nitrate, chloride, acetate, or sulfate are commonly considered as valid options for that aim. However, recent studies have shown that different salts of the same metal at the same cationic concentration may exhibit different toxicities to plants and soil organisms. This information should be considered when selecting data to use for developing toxicological criteria for soil environment. A comparative study was carried out to evaluate the toxicity of five nickel (Ni) salts: NiCl₂, NiSO₄, Ni(II)-citrate, Ni(CH₃COO)₂, and Ni(II)-EDTA (ethylenediaminetetraacetate), on maize seedlings. The plant metrics used were plant height, shoot and root biomass, leaf soluble sugars and starch, and the Ni contents of the shoots and roots. The results indicated that when Ni was added to the soil, toxicity varied with the selected anionic partner with the following toxicity ranking NiSO₄ < Ni(CH₃COO)₂ < Ni(II)-citrate < NiCl₂ < Ni(II)-EDTA. Taking the plant-height metric as an example, the effective concentrations for 50% inhibition (EC50) were 3148 mg·kg(-1) for NiSO₄, 1315 mg·kg(-1) for NiCl₂, and 89 mg·kg(-1) for Ni(II)-EDTA. Compared with the Ni in the other salts, that in Ni(II)-EDTA was taken up the most efficiently by the maize roots and, thus, resulted in the greatest toxic effects on the plants. Nickel generally reduced leaf soluble sugars, which indicated an effect on plant carbohydrate metabolism. The outcome of the study demonstrates that different salts of the same metal have quite different ecotoxicities. Therefore, the anionic counterpart of a potentially toxic metal cation must be taken into account in the development of ecotoxicological criteria for evaluating the soil environment, and a preferred approach of leaching soil to reduce the anionic partner should also be considered.
在土壤生态毒理学研究中，有毒金属通常以溶解度相对较高的无机盐或有机盐形式添加。硝酸盐、氯化物、醋酸盐或硫酸盐通常被视为实现该目的的有效选择。然而，最近的研究表明，相同阳离子浓度下同一金属的不同盐类对植物和土壤生物可能表现出不同的毒性。在选择用于制定土壤环境毒理学标准的数据时，应考虑这一信息。开展了一项比较研究，以评估五种镍（Ni）盐：NiCl₂、NiSO₄、柠檬酸镍（II）、Ni(CH₃COO)₂和乙二胺四乙酸镍（II）（乙二胺四乙酸）对玉米幼苗的毒性。所使用的植物指标包括株高、地上部和根部生物量、叶片可溶性糖和淀粉，以及地上部和根部的镍含量。结果表明，当镍添加到土壤中时，毒性随所选阴离子伴侣的不同而变化，毒性排序如下：NiSO₄ < Ni(CH₃COO)₂ < 柠檬酸镍（II） < NiCl₂ < 乙二胺四乙酸镍（II）。以株高指标为例，50%抑制率的有效浓度（EC50）对于NiSO₄为3148 mg·kg(-1)，对于NiCl₂为1315 mg·kg(-1)，对于乙二胺四乙酸镍（II）为89 mg·kg(-1)。与其他盐中的镍相比，乙二胺四乙酸镍（II）中的镍被玉米根吸收的效率最高，因此对植物产生的毒性影响最大。镍通常会降低叶片可溶性糖含量，这表明对植物碳水化合物代谢有影响。该研究结果表明，同一金属的不同盐类具有截然不同的生态毒性。因此，在制定评估土壤环境的生态毒理学标准时，必须考虑潜在有毒金属阳离子的阴离子对应物，还应考虑采用淋洗土壤以减少阴离子伴侣的优选方法。
