Simazine, metribuzine and nitrates in ground water of agricultural areas of Portugal

Abstract

From 1996 to 1998, residues of simazine, metribuzine and nitrates in ground water (irrigation and drinking) were monitored in wells of the main vineyard, apple and pear orchards, potato and tomato growing areas of “Ribatejo e Oeste”;, an important agricultural region of Portugal. Of a total of 214 samples collected in nine different areas, simazine was the most frequently detected herbicide. It was measured in 96 water samples (44.9%) and reached a maximum concentration of 0.43 μg/L. Metribuzine was found in 15.4% of the samples with a maximum concentration of 1.45 ug/L. Levels of metribuzine and simazine above 0.1 ug/L were found respectively in 4.7% and 6.1% of the total number of analysed samples. Only residues of simazine were detected in ground water for human consumption. Nitrates were also analysed and levels above the maximum concentration of 50 mg/L were found in some areas, reaching a maximum concentration value of 276mg/L.