Abstract
Pesticides have become an integral part of modern intensive agriculture and are applied extensively on a wide range of crops. Viticulture is one of the most pesticide intensive forms of agriculture due to the vines susceptibility for fungal diseases like powdery mildew. Although the use of pesticides has apparent benefits,
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it poses a risk for human health and non-target species in surrounding ecosystems. Since the introduction a lot of improvements have been made on the toxicity and environmental persistence of pesticides, but there is still a lot unknown about the environmental fate and community level effects of different compounds. The behavior of pesticides in soils is often poorly understood because laboratory results don’t translate to field conditions. Pesticides are believed to be immobile once they are sorbed to soil particles, but can be transported with particulate matter following erosion processes. This study aims to determine the levels of pesticide residues present in vineyard soils after years of pesticide application and to quantify the particle- facilitated transport of pesticide residues driven by soil erosion caused by runoff events.
Three study sites with different soil types were selected in the Sao Lourenço sub-basin in Portugal. Plots were installed and soil and sediment samples were collected following runoff events. Collected samples were analyzed for pesticide residues using liquid chromatography mass spectrometry (LC MS/MS).
Residues of six commonly applied fungicides (dimethomorph, pyrimethanil, pyraclostrobin, metalaxyl, penconazole and tebuconazole), one herbicide (glyphosate) and one metabolite (AMPA) were detected in the collected samples. Except for 4 samples of 1 site, all samples contained quantifiable levels of at least 1 compound. Except for dimethomorph at humic cambisol, no patterns of degradation were detected during the study period. Concentrations of glyphosate and AMPA were the highest of the detected compounds and were at least one order of magnitude higher than for the other compounds. Residue concentrations for glyphosate and AMPA were significantly higher in sediment than in soil and were related to particle size and organic matter content. Transport of particle-bound pesticide residues was highest at the site with the highest sediment export. The results of this study indicate that especially for glyphosate and AMPA, particle facilitated transport is a serious concern in areas with high erosion rates.
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