Investigation of the presence of glyphosate and its major metabolite AMPA in Greek soils.

Glyphosate is a broad-spectrum, non-selective, post-emergence herbicide that controls weeds by inhibiting their ability to synthesize amino acids. It is characterized by high persistence and adsorption to soil, with its dissipation to be highly correlated to the climatic conditions. After its degradation in soil, aminomethylphosphonic acid (AMPA) is the sole and major metabolite produced, characterized also by high persistence and adsorption. Both substances have the potential to remain in soil rather than move to other environmental compartments. Considering the recent intense debate during the EU renewal of glyphosate along with its wide use, it is apparent that both glyphosate and AMPA require further attention and information on their occurrence and distribution in EU soils. The present study does constitute the first extended soil monitoring survey of glyphosate and AMPA with samples derived during the years 2013-2015, from the highest extent of the Greek territory. Specific attention was given to areas of high agricultural production as well as to urban areas, since glyphosate-containing products are also registered for non-professional uses. The positive samples represented the 36.7% for glyphosate and 44.9% for AMPA, while the detected residues fluctuated from 0.026 to 40.6 μg g-1 and from 0.01 to 2.5 μg g-1 for glyphosate and AMPA, respectively. Our findings can constitute a basis for the determination of the background concentration levels of glyphosate and its metabolite in the Greek territory. As such, apart from being the first study for glyphosate monitoring in Greece, the most significant highlights recognized in the present work are the following:The high levels of glyphosate and AMPA residues in urban areas that indicate possible misuse of pesticidesThe generally low detection in the main agricultural basins and particularly near water recipientsThe fact that a potential for misuse of herbicides cannot be excluded even in the case of agricultural areas (considering that the maximum detection was in an olive grove and exceeded the model-predicted concentrations by 13 times).