ISO 21226:2019

Overview

ISO 21226:2019 - Soil quality: Guideline for the screening of soil polluted with toxic elements using soil magnetometry - defines a standardized screening geophysical method that uses measurements of magnetic susceptibility (κ) to indicate potential soil pollution with trace elements associated with technogenic magnetic particles (TMPs). The standard specifies field and laboratory procedures, sampling protocols, data mapping and reporting guidelines to produce magnetic susceptibility maps that direct follow‑up geochemical analysis.

Key topics and technical requirements

• Measurement principle: Use of magnetic susceptibility as a proxy for cumulative anthropogenic deposition of potentially toxic elements (PTEs) carried by TMPs.
• Scope limitations: Applicable to TMP‑related airborne emissions (e.g., combustion, metallurgy, cement, waste landfills, transport). Not applicable to pollutants not associated with TMPs (organic contaminants, agricultural emissions) or to soils developed on bedrock with extremely high natural magnetism (rare).
• Sampling and measurement procedures:
  • Design of a measurement network for area screening.
  • Topsoil surface κ measurements in situ and vertical profile measurements using soil cores (minimum core dimensions specified in the standard).
  • Laboratory measurements (mass susceptibility, frequency dependence χfd) to identify superparamagnetic contributions and validate field data.
• Data processing and mapping: Creation of 2D/3D magnetic susceptibility maps, data analysis and discrimination of areas with elevated κ for targeted geochemical sampling.
• Reporting and validation: Requirements for a screening report and annexed guidance relating κ to trace element contamination, performance examples and validation summaries.

Practical applications and users

ISO 21226:2019 is designed for practical use where rapid, cost‑effective screening of large areas is needed to detect soil pollution from airborne, high‑temperature industrial sources. Typical users include:

• Environmental consultants and remediation practitioners performing site assessments and brownfield screening.
• Soil scientists and geochemists integrating geophysical screening with targeted chemical analysis.
• Regulators and environmental agencies planning monitoring networks and risk prioritization.
• Industrial environmental monitoring teams (metallurgy, power plants, cement works) and researchers studying long‑range transport of trace elements.

Practical benefits include reduced sampling and laboratory costs by using magnetic susceptibility mapping to focus geochemical analyses on the most affected zones and improved spatial understanding of deposition patterns from TMP‑related emissions.

Related standards (if applicable)

ISO 21226:2019 complements other soil quality and geochemical sampling standards and geophysical survey guidance used by environmental professionals. Users should integrate this screening method with validated geochemical analyses and local regulatory frameworks when assessing soil contamination.