Occurrence of Waste Herbicides in Surface Water from North of São Paulo (Brazil)

The incorrect use of herbicides can cause the contamination of soil and aquatic ecosystems. In this study, we evaluated the contamination of surface water samples from the northern state of São Paulo, Brazil. Samples were collected from rain, streams and lakes in three seasons in different agricultural areas. Liquid chromatography coupled with high performance mass spectrometry was used to analyze water contamination by the following herbicides: ametryn, amicarbazone, clomazone, diclosulam, diuron, hexazinone, imazapic, imazapyr, isoxaflutole, s-metolachlor, sulfentrazone, sulfometuron-methyl and tebuthiuron. According to the method, the limits of quantification were 3.13 μg L-1 for diuron and 0.391 μg L-1 for the other herbicides. It was observed that 82% of all the samples contained at least one herbicide, and clomazone was the most common product. The highest quantized values were found for streams: s-metolachlor (10.2 hg L-1), diuron (7.65 and 5.49 μg L-1) and hexazinone (4.3 μg L-1). The results indicate that surface water from the north of São Paulo contains residual herbicides in quantifiable levels.