Impact of agricultural practices on groundwater quality: Case of Gharb region-Morocco

International audienceFertilizer and pesticide use due to agricultural activities is the most sensitive cause of groundwater contamination. Research in the Mnasra area on district in the coastal zone of Gharb plain in northwest Morocco sought to determine spatial and temporal variability of groundwater nitrate (NO-3) and pesticide concentrations in 2012. The monitoring has focused on shallow groundwater near agricultural fields (9 locations). Total of 36 groundwater samples were collected (March, April, May and September) and analyzed for NO-3 concentrations by ionic chromatography and pesticides residues by accelerated solvent extraction (ASE). For all groundwater samples, NO-3 concentrations were exceeding the critical value of 50 mg.L-1. Three pesticides benalaxyl, chlorpyrifos and cypermethrin have been followed. No pesticide molecules were detected, what can be explained by the low quantity applied of these compounds in the area, the use of foliar spray products or the degradation of molecules on the top soil before reaching the groundwater