metallifraktio

Metallifraktio is a term used in geochemistry and environmental science to describe how metals exist within solid materials such as soils, sediments, dust, or mine residues in distinct fractions or phases. The concept captures metal speciation and potential mobility, and it is used to assess bioavailability, environmental risk, and the effectiveness of remediation.

The distribution of metals into fractions is typically investigated with sequential extraction procedures that separate metals into operationally defined fractions. Common fractions include exchangeable, carbonate-bound, iron and manganese oxide-bound, organic-bound, and residual. The exact reagents and steps vary between schemes, with foundational approaches like Tessier et al. (1979) and later BCR methods guiding many studies. These schemes aim to provide a reproducible estimate of how metals partition among different solid-phase associations.

Applications of metallifraktio include risk assessment of contaminated sites, tracing contamination sources, evaluating remediation strategies, and predicting metal uptake by organisms. The resulting fraction distribution helps prioritize remediation, monitor progress, and inform management decisions, especially regarding potential mobility and bioavailability under changing environmental conditions.

Limitations exist because fractions are operationally defined and may not perfectly reflect natural processes. Extraction steps can alter speciation, metals may redistribute during analysis, and results can be influenced by sample handling and matrix effects. Consequently, metallifraktio is best used as a comparative or qualitative tool rather than a direct measurement of bioavailability. In Finnish-language literature, the term metallifraktio is common; in English, the concept is often described as metal fractionation or metal speciation.