Identification of contaminants of concern in the upper Tagus river basin (central Spain). Part 1: Screening, quantitative analysis and comparison of sampling methods

Andreu Rico; Alba Arenas-Sánchez; Covadonga Alonso-Alonso; Isabel López-Heras; Leonor Nozal; David Rivas-Tabares; Marco Vighi

doi:10.1016/j.scitotenv.2019.02.250

Identification of contaminants of concern in the upper Tagus river basin (central Spain). Part 1: Screening, quantitative analysis and comparison of sampling methods

Sci Total Environ. 2019 May 20:666:1058-1070. doi: 10.1016/j.scitotenv.2019.02.250. Epub 2019 Feb 21.

Authors

Andreu Rico¹, Alba Arenas-Sánchez², Covadonga Alonso-Alonso², Isabel López-Heras², Leonor Nozal³, David Rivas-Tabares², Marco Vighi²

Affiliations

¹ IMDEA Water Institute, Science and Technology Campus of the University of Alcalá, Avenida Punto Com 2, 28805, Alcalá de Henares, Madrid, Spain. Electronic address: andreu.rico@imdea.org.
² IMDEA Water Institute, Science and Technology Campus of the University of Alcalá, Avenida Punto Com 2, 28805, Alcalá de Henares, Madrid, Spain.
³ IMDEA Water Institute, Science and Technology Campus of the University of Alcalá, Avenida Punto Com 2, 28805, Alcalá de Henares, Madrid, Spain; Institute of Applied Chemistry and Biotechnology (CQAB), University of Alcalá, Madrid, Spain.

PMID: 30970472
DOI: 10.1016/j.scitotenv.2019.02.250

Abstract

Pesticides and point source contaminants (primarily pharmaceuticals) were monitored in 16 sampling sites of the upper Tagus river basin during spring, summer and autumn of 2016. A qualitative screening analysis was performed using a library of 430 compounds. Next, a novel method was implemented for the selection and quantification of contaminants with LC-MS/MS. The method is based on the frequency of detection in the screening, ecotoxicity data and the potential use in the watershed. Moreover, the efficacy of grab samples and passive samples (POCIS) in detecting compound-specific exposure patterns was compared during the summer sampling campaign. The screening method detected the presence of 268 compounds in the study area, out of which 52 were selected for the quantitative analysis (20 pesticides and 32 point source chemicals). Although very helpful in the prioritization exercise, the qualitative screening demonstrated some biases and the need for improvement by using more effective instruments for confirming positive results. Grab samples proved not to be fully suitable for contaminants with discontinuous exposure such as pesticides, which may be underestimated, but offer a sufficient basis for the characterization of contaminants coming from urban wastewaters. All selected chemicals showed a very high concentration variability due to differences among sampling sites, which are related to agricultural intensity and demographic pressure. Some insecticides (chlorpyrifos, dimethoate, imidacloprid), herbicides (diuron, metribuzine, simazine, terbuthylazine), and fungicides (carbendazim) were measured at concentrations exceeding 100 ng/L; while paracetamol, ibuprofen, some antibiotics (azithromycin, sulfamethoxazole, trimethoprim) and life-style compounds (caffeine, paraxanthine, nicotine) were found at very high concentrations (up to several μg/L). The results of this work represent the basis for the development of an ecological risk assessment for the aquatic ecosystem in the upper Tagus river basin and for the identification of basin-specific contaminant mixtures of environmental concern.

Keywords: Liquid chromatography-mass spectrometry; Passive sampling; Pesticides; Pharmaceuticals; River monitoring; Screening.