title: A Comparative Study on the Uptake and Toxicity of Nickel Added in the Form of Different Salts to Maize Seedlings.
abstract: 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.
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. niejing816@126.com.|State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. niejing816@126.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Nie
authors.affiliation: Key Laboratory of Farming System, Ministry of Agriculture, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China. panyuqiang111@163.com.
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Department of Safety Engineering, China Institute of Industrial Relations, Beijing 100048, China. shijing8008@163.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Shi
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. yan.guo@cau.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. yanzg@craes.org.cn.
authors.forename: Zengguang
authors.initials: Z
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. duan_jasmine@126.com.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. xumeng@craes.org.cn.
authors.forename: Meng
authors.initials: M
authors.lastname: Xu
mesh_terms: D002681:China; D009532:Nickel / Q000032:analysis* / Q000633:toxicity*; D018517:Plant Roots / Q000737:chemistry; D012492:Salts / Q000032:analysis* / Q000737:chemistry; D036226:Seedlings / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D003313:Zea mays / Q000737:chemistry*
chemical_list: D012492:Salts; D012989:Soil Pollutants; D009532:Nickel
keywords: maize; nickel accumulation; nickel salts; nickel toxicity; soil contamination