Study of the presence of priority pesticides in surface water of river basins located in two areas of intensive dairy farming in the NW Spain (Galicia)

Abstract

This study provides data about the monitoring over two years of 54 target pesticides in surface water of two river catchments located in two areas of the most intensive dairy farms of Galicia (NW Spain). Solid phase extraction of water samples followed by multi-residue analysis on a triple quadrupole mass spectrometer instrument coupled to liquid chromatography (LC-MS/MS) enabled to acquire the results. The most frequently detected pesticides were acetochlor, alachlor, atrazine and terbuthylazine, as well as some of their metabolites. The concentration profiles of these four substances show a seasonal variation, the highest concentrations corresponding to the period of maize sowing and the application of herbicides. Of the seven priority pesticides evaluated, only alachlor and atrazine were detected. Their follow-up revealed that the concentration thresholds laid down by the EQS for these substances were never exceeded. The sum of the concentrations of the most detected compounds reached a maximum slightly higher than 1 µg L⁻¹. The sum of the AAC of these compounds was well below the allowed average values. Some comparisons made with studies carried out in other basins in Europe reveal that the compounds detected in the present study are usually present in rivers near intensive agricultural areas. However, the maximum concentrations of pesticides found in our survey were generally lower than those registered in these European river basins.

Keywords:

• priority pesticides
• surface water
• maize crops
• environmental quality standards

Acknowledgements

This research was supported by FEDER funds and projects PGIDIT05RAG50301PR (Ministry of research and development, Autonomic government of Galicia), RTA2007-00091 (INIA, Spanish Institute for Research on Agrarian and Food Technology).