Using soil health to assess ecotoxicological impacts of pollutants on soil microflora

Microorganisms are essential for a properly functioning soil ecosystem. However, few methods allow an ecotoxicological evaluation of pollutant impact on the soil microbial community. This review proposes the use of the concept of soil health as an ecotoxicological evaluation tool for soil microflora. Initially limited to sustainable agriculture, the concept of soil health is now being applied to novel situations including contaminated and remediated soils. A large amount of work has been published in the last few decades on soil health indicators, and a review of the most relevant studies is presented here. The most cited work is that of the S-5518 committee set up in 1997 by the Soil Science Society of America (SSSA), which proposed to define soil quality as being "the capacity of a soil to function within the limits of an ecosystem, to support biological production, to maintain environmental quality and to support fauna and flora health." The soil health indicators reviewed here are the ones based on this definition because it relates well to sustainability and durability of the soil functions. Several indicators proposed in these studies could be employed in the evaluation of the ecotoxicological impact of pollutants on the soil microbial community, including microbial diversity, microbial activity, and functional stability. However, research is still required to unify the concept, to set threshold values, and to standardize methodologies.