Assessing drugs of abuse distribution in Turia River based on geographic information system and liquid chromatography mass spectrometry.

Drugs of abuse are continuously discharged into wastewaters as part of their elimination process. Pollution at very low concentrations appears to be broad in environmental compartments near populated areas. A total of 42 drugs of abuse and metabolites were analysed in surface water samples collected in 2012 and 2013 by solid phase extraction and liquid chromatography coupled to mass spectrometry. Analytical results of target compounds were georeferenced and integrated into a geographical information systems (GIS). Ecotoxicological risk of drugs of abuse detected in the Turia River was evaluated in this study by calculating risk quotient (RQ). In 2012, 6 compounds were detected in a total of 22 points. In 2013, 7 compounds were found in a total of 31 sampling sites, 4 of them also detected in 2012. The most frequent compound was benzoylecgonine, detected in 9 sampling points in 2012 and 8 in 2013, at an average concentration of 25.4ng/L and 14.02ng/L. Codeine reached the maximum concentration of detected compounds (101ng/L) in 2013. GIS provided the spatial incidence of drugs of abuse along the Turia River basin. The distribution of these compounds in 2012 and 2013 shows that the highest concentrations and frequency of drugs of abuse run into places with the highest population density. The RQ obtained from measured concentrations of detected drugs predict that no short-term environmental risk might be expected. Further research including multi-stressors studies with more potentially persistent or pseudo-persistent organic pollutants in surface waters is needed to establish relationships with human pressure in a river basin.