Metal Ecotoxicity Studies with Artificially Contaminated versus Anthropogenically Contaminated Soils: Literature Review, Methodological Pitfalls and Research Priorities

Abstract: Most ecotoxicological studies on the toxicity of metals in soil are conducted using artificially contaminated soils, i.e., originally uncontaminated soils to which increasing amounts of metals are added in the form of soluble salts in a laboratory setting. This approach has been rightly criticized because of the difficulty of extrapolating the results to real field situations. In our literature review, all studies without exception demonstrated a higher toxicity of metals in artificially contaminated soils than in anthropogenically contaminated soils exposed to pollution a few decades ago. Therefore, the traditional approach to the analysis of metal toxicity in soils, which is based on metal enrichment, has become outdated; new studies with such soils cannot provide any original insights at this time. We encourage researchers of metal pollution from anthropogenic emissions to analyze dose-effect relationships using native field-collected soils, rather than adopting the standard approach, which is based on artificially contaminated soils.