Combining an effect-based methodology with chemical analysis for antibiotics determination in wastewater and receiving freshwater and marine environment

Two different methodologies were combined to evaluate the risks that antibiotics can pose in the environment; i) an effect-based methodology based on microbial growth inhibition and ii) an analytical method based on liquid-chromatography coupled to mass spectrometry (LC-MS). The first approach was adapted and validated for the screening of four antibiotic families, specifically macrolides/β-lactams, quinolones, sulfonamides and tetracyclines. The LC-MS method was applied for the identification and quantification of target antibiotics; then, the obtained results were combined with ecotoxicological data from literature to determine the environmental risk. The two methodologies were used for the analysis of antibiotics in water samples (wastewater, river water and seawater) and biofluids (fish plasma and mollusk hemolymph) in two monitoring campaigns undertaken in the Ebro Delta and Mar Menor Lagoon (both in the Mediterranean coast of Spain). Both approaches highlighted macrolides (azithromycin) and quinolones (ciprofloxacin and ofloxacin) as the main antibiotics in wastewater treatment plant (WWTP) effluents with potential risk for the environment. However, no risk for the aquatic life was identified in the river, lagoon and seawater as antibiotic levels were much lower than those in WWTP effluents. Fish from Ebro River were the organisms presenting the highest antibiotic concentration when compared with bivalves (mussels) from the Mediterranean Sea and gastropods (marine snails) from the Mar Menor Lagoon. The effect-based methodology successfully determined antibiotic risk in wastewater, but its applicability was less clear in environmental waters such as seawater, due to its high detection limits. Improving sample preconcentration could increase the method sensibility. Overall, combination of both methodologies provides comprehensive insights in antibiotic occurrence and risk associated in areas under study.

This work has received funding from the Spanish Ministry of Economy and Competitiveness through the PLAS-MED (CTM2017-89701-C3-2-R) project. Authors acknowledge the support from the Economy and Knowledge Department of the Catalan Government through Consolidated Research Group (ICRA-ENV 2017 SGR 1124 and 2017-SGR-1404-Water and Soil Quality Unit). The authors acknowledge the IEO & CSIC staff for their help in the sampling campaigns. Albert Serra-Compte acknowledges the FI-DGR research fellowship from the Catalan Government (2018FI_B2_00170) and the Nereus Cost Action grant. Sara Rodriguez-Mozaz acknowledges the Ramon y Cajal program (RYC-2014-16707) and Diana Álvarez-Muñoz the support of the project XENOMETABOLOMIC (CTM2015-73179-JIN) (AEI/FEDER/UE). Authors kindly acknowledge Generalitat DGPAM (Fisheries Department). The authors also acknowledge support from CERCA Programme/Generalitat de Catalunya.

Peer reviewed