Overview
EN ISO 21479:2020 (ISO 21479:2019) specifies a bioanalytical method to assess soil quality by measuring the leaf fatty acid composition of plants grown in soils of interest. The method uses the Omega‑3 index (leaf fatty acid profiles, expressed as FAMEs) as a sensitive bio‑indicator of pollutant effects on soil flora. It is intended for comparative assessments between areas (e.g., contaminated vs. reference sites) and cannot establish an absolute or intrinsic soil quality threshold.
Key topics and technical requirements
- Scope and limitation
- Designed to compare soil quality across areas; not to define an optimal Omega‑3 index for a homogeneous soil.
- Applicable to contaminated soils, amended soils, soils after remediation, and soils with waste products (slurry, manure, sludge, composts).
- Sampling and sample handling
- Guidance for leaf tissue sampling strategies and contamination control.
- Only small amounts of fresh leaf tissue are required (typically 20–50 mg), minimizing plant damage.
- Plant tissues can be stored in methanol for several days before analysis.
- Analytical workflow
- Extraction and conversion to fatty acid methyl esters (FAMEs) and instrumental analysis (chromatography) of FAME composition.
- Annexes provide details on apparatus, reagents, analysis procedures, and example chromatograms.
- Quality and reproducibility
- Ring test results (Annex A) address method repeatability and reproducibility.
- Annex B describes an ex situ option: measuring the Omega‑3 index of Lactuca sativa seedlings grown under controlled (phytotronic) conditions and compared with controls.
- Safety
- Warning about handling contaminated soils - potential toxic or infectious hazards; follow occupational health precautions.
Applications
- Detecting sub‑lethal effects of metals, herbicides and organic contaminants on plant physiology.
- Monitoring the effectiveness of soil remediation or amendments by comparing pre/post-treatment soil-induced changes in plant fatty acids.
- Screening contaminated or waste‑amended soils in environmental site assessments and long‑term monitoring programs.
- Complementary tool to chemical analyses and biometric endpoints (germination, biomass), offering greater sensitivity in some cases.
Who should use this standard
- Environmental laboratories and analytical chemists performing soil bioassays.
- Soil scientists, ecotoxicologists, remediation consultants and regulatory agencies assessing contaminated land.
- Researchers studying plant responses to soil pollutants and practitioners running site monitoring programs.
Related standards
- Part of the ISO family for soil quality (developed by ISO/TC 190). Use alongside chemical and physical soil testing standards and other biological characterization standards for comprehensive site assessment.
Keywords: soil quality, ISO 21479, leaf fatty acid composition, Omega‑3 index, contaminated sites, remediation, FAMEs, Lactuca sativa.