Distribution of antibiotics in water, sediments and biofilm in an urban river (Córdoba, Argentina, LA)

In this study, we evaluated the distribution of up to forty-three antibiotics and 4 metabolites residues in different environmental compartments of an urban river receiving both diffuse and point sources of pollution. This is the first study to assess the fate of different antibiotic families in water, biofilms and sediments simultaneously under a real urban river scenario. Solid phase extraction, bead-beating disruption and pressurized liquid extraction were applied for sample preparation of water, biofilm and sediment respectively, followed by the quantification of target antibiotics by UPLC-ESI-MS/MS. Twelve antibiotics belonging to eight chemical families were detected in Suquía River samples (67% positive samples). Sites downstream the WWTP discharge were the most polluted ones. Concentrations of positive samples ranged 0.003-0.29 µg L-1 in water (max. cephalexin), 2-652 µg kg-1d.w. in biofilm (max. ciprofloxacin) and 2-34 µg kg-1d.w. in sediment (max. ofloxacin). Fluoroquinolones, macrolides and trimethoprim were the most frequently detected antibiotics in the three compartments. However cephalexin was the prevalent antibiotic in water. Antibiotics exhibited preference for their accumulation from water into biofilms rather than in sediments (bioaccumulation factors > 1,000 L kg-1d.w. in biofilms, while pseudo-partition coefficients in sediments < 1,000 L kg-1d.w.). Downstream the WWTP there was an association of antibiotics levels in biofilms with ash-free dry weight, opposite to chlorophyll-a (indicative of heterotrophic communities). Cephalexin and clarithromycin in river water were found to pose high risk for the aquatic ecosystem, while ciprofloxacin presented high risk for development of antimicrobial resistance. This study contributes to the understanding of the fate and distribution of antibiotic pollution in urban rivers, reveals biofilm accumulation as an important environmental fate, and calls for attention to government authorities to manage identified highly risk antibiotics.

This study has been co-financed by the European Union through the European Regional Development Fund (FEDER), by the Agencia Nacional de Promoción Científica y Técnica (FONCyT/PICT-2015-01784) and the International Atomic Energy Agency (CRP: D52039, CN:18849). It has also been partly supported by the Generalitat de Catalunya (Consolidated Research Group: Catalan Institute for Water Research 2014 SGR 291). Lúcia H.M.L.M. Santos thanks the Juan de la Cierva program (IJCI-2017-32747) and Sara Rodríguez-Mozaz thanks the Ramon y Cajal program (RYC-2014-16707) from the Spanish State Research Agency of the Spanish Ministry of Science, Innovation and Universities (AEI-MCIU). ICRA researchers thank funding from CERCA program.Argentinean authors would also like to thank CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas-Argentina) and Sci-Hub for useful access to knowledge.

Peer reviewed