Transport of organic contaminants in subsoil horizons and effects of dissolved organic matter related to organic waste recycling practices
2016
Chabauty, Florian | Pot-Genty, Valerie | Deschamps, Marjolaine | Bernet, Nathalie | Labat, Christophe | Benoit, Pierre | Ecologie fonctionnelle et écotoxicologie des agroécosystèmes (ECOSYS) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | Université Paris-Saclay | European Commission [226536]; Ile-de-France region; Veolia Environment group Funding Text : The work was carried as part of the GENESIS project on groundwater systems financed by the European Commission 7thFP contract 226536. The authors also acknowledge the Ile-de-France region for funding for ultra-performance liquid chromatography/MS-MS analyses, and the useful help of Jean-Noel Rampon for field sampling. Finally, we acknowledge the Veolia Environment group for the financial support of the QualiAgro field site.
Compost amendment on agricultural soil is a current practice to compensate the loss of organic matter. As a consequence, dissolved organic carbon concentration in soil leachates can be increased and potentially modify the transport of other solutes. This study aims to characterize the processes controlling the mobility of dissolved organic matter (DOM) in deep soil layers and their potential impacts on the leaching of organic contaminants (pesticides and pharmaceutical compounds) potentially present in cultivated soils receiving organic waste composts. We sampled undisturbed soil cores in the illuviated horizon (60-90 cm depth) of an Albeluvisol. Percolation experiments were made in presence and absence of DOM with two different pesticides, isoproturon and epoxiconazole, and two pharmaceutical compounds, ibuprofen and sulfamethoxazole. Two types of DOM were extracted from two different soil surface horizons: one sampled in a plot receiving a co-compost of green wastes and sewage sludge applied once every 2 years since 1998 and one sampled in an unamended plot. Results show that DOM behaved as a highly reactive solute, which was continuously generated within the soil columns during flow and increased after flow interruption. DOM significantly increased the mobility of bromide and all pollutants, but the effects differed according the hydrophobic and the ionic character of the molecules. However, no clear effects of the origin of DOM on the mobility of the different contaminants were observed.
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