Does fresh organic matter addition to an industrial soil have an impact on soil structure and on PAH concentration, repartition and availability?

Abstract

A simulation of 10 years of maize culture was performed by incubation of industrial soilhighly contaminated by polycyclic aromatic hydrocarbons (PAH) and containing exclusivelyanthropogenic organic matter (OM) mixed with maize residue. The aim was to evaluate theimpact of the fresh OM incorporation on the soil structure and consequently on thecontaminants repartition, concentration and availability. Water granulodensimetricfractionation was carried out to isolate five water stable material fractions (coarse and finesands, coarse and fine silts and clays). The evolution of the added maize repartition in thesefractions was followed using δ13C. Total and available PAH content in the bulk soil as well asin the different fractions were determined by solvent and Tenax® resin extractionrespectively. The monitoring of soil structure showed an aggregation process in the amendedsoil after 3 months of incubation probably due to the promoting of microbial activity. Amongthe different fractions, fine silts distinguished themselves by enrichment in total organiccarbon and in δ13C due to the added carbon. However, the results showed no significantimpact on pollution, which remained stable in terms of concentration, distribution andavailability. This experiment suggests that a culture on this soil wouldn’t mobilize thepollution