Evaluation of Distribution and Chemical Associations between Cobalt and Manganese in Soils by Continuous‐Flow Sequential Extraction

Abstract

In this study, a strong association between cobalt (Co) and manganese (Mn) in different geochemical soil phases (fractions) was evaluated using a continuous‐flow sequential extraction technique employing a modified Tessier extraction scheme. With the flow system, detailed extraction profiles of Co and Mn in soils could be obtained by plotting concentrations of the elements extracted against extraction time (plots referred to as extractograms). Extractograms may be used as an indicator of whether the elements dissolving in the same extraction step are closely associated, or are merely extractable with the same reagent. From the soil samples studied, the coincidence of Co and Mn peaks seems to indicate a close association of these elements in the exchangeable, reducible, and oxidizable fractions. Analysis of flow extraction data suggested that the association between Co and Fe is not as strong as reported in previous studies based on the statistical analysis of batch fractionation data.

Keywords:

• Manganese oxides
• flow
• sequential extraction
• fractionation

Acknowledgments

The authors would like to gratefully thank the Royal Golden Jubilee Grant and the Thailand Research Fund for funding this project, and the Postgraduate Education and Research Program in Chemistry (PERCH) for partial support.