Pesticide residues in groundwaters and soils of agricultural areas in the Águeda River Basin from Spain and Portugal

Abstract

This research has evaluated the agricultural impact of the use of pesticides in small agricultural areas in the Águeda river basin, which straddles the Spanish-Portuguese border. Sixteen pesticides frequently used in the area, including herbicides, fungicides and insecticides and some of their degradation products, were monitored in 52 groundwater samples and 42 soil samples taken around them, using a developed multi-residual analytical method based on SPE-LC-MS. Sampling was carried out in two different seasons (winter and summer). The results indicated the presence of pesticides at several levels, both in groundwaters and soils. Thirteen of the pesticides studied were detected in one or more of the groundwater samples analysed, but only three pesticides were detected in the soil samples. Terbuthylazine, cyprodinil, tebuconazole and chlorpyrifos were the pesticides most frequently detected in groundwaters, whereas terbuthylazine, metalaxyl and tebuconazole were the sole compounds detected in soils. The distribution of the concentrations in groundwaters indicated that up to 80% and 70% of the samples collected in the summer on the Spanish and Portuguese sides, respectively, exceed the quality standards of 0.1 µg L⁻¹ for one or more individual compounds and, in turn, up to 64% and 40% exceed the quality standards of 0.5 µg L⁻¹ for all compounds. The presence of pesticide residues in the groundwaters and soils analysed may well be explained by the use of these compounds in agricultural practices.

Keywords:

• agricultural impact
• groundwater
• multi-residue analysis
• pesticide
• soil

Acknowledgements

This work was funded by the EU and co-financed by FEDER and the POCTEP Programme 2007–2013 (Ref. EC: 0410_AGUEDA_3_E). E. Herrero-Hernández thanks CSIC for his JAE-Doc, and E. Pose-Juan and A. Álvarez-Martín thank the Spanish Ministry of Science and Innovation for their Juan de la Cierva contract and FPI fellowship, respectively.

This work was first presented at the 7th European Conference on Pesticides and Related Organic Micropollutants in the Environment and 13th Symposium on Chemistry and Fate of Modern Pesticides, 7–10 October 2012, Porto, Portugal.