Présentations Colloques

Flash Poster
Session 5.04: Emerging contaminants in the water cycle and risk to Groundwater
Meritxell Gros
Occurrence and fate of antibiotics in soils fertilized with manure and evaluation of their persistence and potential to migrate to groundwater bodies
Animal manure is extensively used as fertilizer in agriculture because it contains essential nutrients for plant growth. However, fertilization of crops using animal manure may lead to contamination of groundwater resources by the introduction of organic pollutants, such as antibiotics and pharmaceuticals used in veterinary medicine. Once animal manure is applied as fertilizer in agricultural soils, recalcitrant pharmaceuticals may persist and accumulate in the soil while others may leach to groundwater bodies. In the present work, the occurrence, distribution and fate of 40 multiple-class antibiotics and veterinary pharmaceuticals was investigated in two field experiments fertilized with animal manure at a rate of 170 kg N ha per year, one with dairy cattle manure and the other with pig slurry (plots size- 3x8 m and 3x10 m, respectively), including control plots without fertilization. Soils under study were very deep, sandy loam textured and calcareous. The fields were cultivated with wheat and barley, alternatively, since 2001. Soil sampling was performed in December 2015, prior to fertilization, and in February and June 2016, two and six months after fertilization, respectively. Moreover, manure used as soil amendment was also analyzed. Soil samples were taken at different soil depths, covering from 0-30 cm, 30-60 cm, 60-90 cm and 90-120 cm. Analysis of veterinary antibiotics and pharmaceuticals was performed by liquid chromatography tandem mass spectrometry to investigate the persistence and mobility of target substances along the soil column. Antibiotics and pharmaceuticals detected in manure (ng g – Ig kg range) were matched with those detected in soil samples (found at low ng g levels). Differences in pollutant concentrations before and after fertilization indicated that repeated fertilization may contribute in building up persistent residues that accumulate in the soil over time. Moreover, the analysis at different depths was useful to identify the pollutants with the highest mobility and those that are more liable to leach to groundwater bodies and deteriorate the quality of aquifers.