Overview
EN ISO 12782-2:2012 (CEN adoption of ISO 12782-2:2012) defines a standardized laboratory method for determining the content of reactive crystalline iron oxides and hydroxides in soils and other materials (including waste) by dithionite extraction. The measured “reactive” iron fraction is intended as an input parameter for geochemical modelling of leaching and speciation, helping translate laboratory leaching data into field-relevant predictions of mobility and bioavailability of trace constituents.
Key topics and technical requirements
- Scope and principle: Method targets well-crystallized iron (hydr)oxides (e.g., goethite, haematite) using a dithionite-based extraction specific to crystalline phases.
- Apparatus and reagents: Standard lists for laboratory equipment and chemicals required to perform the extraction (specified in the standard).
- Sample pretreatment: Guidance on representative sample size, particle size reduction and determination of water content before extraction.
- Extraction procedure: Stepwise protocol for preparing the dithionite extraction solution and performing the extraction (including centrifugation/filtration guidance in an informative annex).
- Analytical determination and calculation: Procedures for quantifying extracted iron, calculating results and expressing reactive iron content for model input.
- Reporting: Required elements of the test report to ensure traceability and reproducibility.
Practical applications
- Geochemical modelling: Provides a measured parameter representing crystalline iron (hydr)oxide surfaces used in models of leaching, speciation and adsorption.
- Environmental risk assessment: Improves prediction of contaminant mobility and bioavailability in soil, landfill and waste scenarios.
- Material characterization: Used in assessment of soils, soil amendments, slags, ashes and recycled materials where iron minerals influence contaminant behaviour.
- Remediation and regulatory support: Supplies standardized data for comparison across sites and for regulatory decision-making.
Who uses this standard
- Environmental and soil testing laboratories
- Geochemists and soil scientists performing model inputs
- Waste characterization and recycling specialists
- Remediation consultants and regulatory agencies involved in risk assessment
Related standards
- ISO 12782-1: Extraction of amorphous iron oxides (ascorbic acid)
- ISO 12782-3: Extraction of aluminium oxides (ammonium oxalate/oxalic acid)
- ISO 12782-4 and ISO 12782-5: Extraction of humic substances (solid and aqueous)
- ISO/TS 21268-4: pH-dependent leaching tests (referenced for modelling workflows)
Keywords: soil quality, geochemical modelling, dithionite extraction, crystalline iron oxides, iron hydroxides, reactive iron, leaching, speciation, EN ISO 12782-2:2012, CEN.
