Effect of sterilization and experimental conditions on the isotopic exchange of nickel in two contrasting soils

• Published in: European journal of soil science 2002-12, Vol.53 (4), p.655-662
• Main Authors: Staunton, S., Barthès, M., Leclerc- Cessac, E., Pinel, F.
• Format: Article
• Language: English
• Subjects: Agricultural sciences; Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Life Sciences; Microbiology; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; Soil study; Soils; Surficial geology
• ISSN: 1351-0754; 1365-2389
• DOI: 10.1046/j.1365-2389.2002.00476.x

Summary A detailed study of the isotopic exchangeability of native nickel is presented for two contrasting soils. Non‐sterile soils were compared with γ‐sterilized soil to assess the role of microbial activity in modifying nickel speciation. The distribution coefficient, Kd, was measured in a range of suspensions and in moist soil. Solution and soil solids were separated by double centrifuging. Soils were wetted with either water or 0.01 m CaCl2 solution. The change in Kd was also recorded for the soils incubated moist over a 6‐week period. Kd values decreased markedly as suspension was more concentrated, and data obtained in moist soil followed the same trend. Data obtained at a soil:solution ratio of 1:1 are closer to those obtained for soil incubated at field capacity (or drier) than those obtained at the more usual 1:10 ratio. Sterilization caused a marked increase in nickel solubility (about a threefold decrease in Kd for one soil and a 25% decrease for the other). Soil analysis showed that sterilization modified only water‐extractable organic carbon and EDTA‐extractable Mn. The effect of solution composition on Kd was less marked. These effects are attributed largely to dissolved organic carbon and easily extractable manganese oxides. There was relatively little change in Kd over the 6‐week period, suggesting that except for strongly anoxic soils, the distribution of nickel measured after 24 hours is a good estimation of Kdin situ. Effet de la stérilisation et des conditions expérimentales sur l'échange isotopique du nickel dans deux sols contrastés Résumé Une étude détaillée de l'échangeabilité isotopique du nickel natif de deux sols contrastés est présentée. Les sols non‐stériles ont été comparés aux sols stérilisés par rayonnement‐γ pour évaluer le rôle de l'activité microbienne dans la modification de la spéciation du nickel. Le coefficient de distribution, Kd, a été mesuré dans une gamme de suspensions et dans le sol humide. La solution et la phase solide du sol ont été séparées par centrifugation en deux étapes. Les sols ont été humectés soit avec l'eau soit avec une solution de 0,01 m CaCl2. La modification du Kd a été suivie pour les sols humides sur une période de 6 semaines. Les valeurs de Kd diminuaient fortement avec l'augmentation de la teneur en solide de la suspension. Les données obtenues avec un rapport sol:solution de 1:1 sont plus proches de celles obtenues pour le sol incubéà la capacité au champ (ou plus sec) que celle obtenu au