Study of the presence of pesticides in surface waters in the Ebro river basin (Spain).

This work studies the presence of a total number of 44 substances found in waters of the Ebro river basin (Spain), all included in the Pesticides Control Network, whose purpose is to monitor diffuse pollution of surface waters caused by pesticides contained in some of the dangerous substances lists established in existing legislation and their high degree of use in the basin. Most of the pesticide sampling points are located in the sections of river that receive run-off waters from various agricultural areas shortly before opening out onto the main river (the Ebro), in areas of special agricultural importance. Water samples are subjected to a solid-liquid extraction as a previous step to their analysis by GC/MS (gas chromatography/mass spectrometry). Pesticides most frequently found and in greater concentrations in the waters of the Ebro river basin are 3,4-dichloroaniline, molinate, desethylatrazine, dimetoate, simazine, atrazine, metolachlor and chlorpyrifos. There are certain compounds that are not detected or their concentrations are below the quantification limit, such as 4-isopropylaniline, ametryn, beta-HCH, delta-HCH, aldrin, isodrin, dieldrin, heptachlor epoxide, endosulfan and endosulfan-sulfate. Diuron appears at specific points in some of the stations.