Contaminants of emerging concern in the Basque coast (N Spain): Occurrence and risk assessment for a better monitoring and management decisions

The study of the presence in the aquatic environment of certain substances considered as contaminants of emerging concern (CEC) is a preliminary step to the analysis of the possible harmful effects on aquatic ecosystems and the establishment of the corresponding environmental quality standards. In order to monitor the occurrence of CECs in the aquatic environment, the European Commission established in 2015 and 2018 two watch-list of substances for Union-wide monitoring in the field of water policy (Decision (EU) 2015/495 and Decision (EU) 2018/840). In the coast of the Basque Country, southeast of the Bay of Biscay, 19 of these watch list substances were monitored quarterly from May 2017 to March 2019. Water samples were collected at the effluent of three wastewater treatment plants and five control points associated with receiving waters (transitional and coastal water bodies). The most frequently quantified substances were azithromycin (91%), imidacloprid (82%), clarithromycin (80%), diclofenac (78%) and erythromycin (73%), with frequencies of quantification higher in wastewaters (83–100%) than in receiving waters (70–85%). In general, concentrations in wastewater were also higher than in receiving waters, indicating a dilution effect in the environment. In receiving waters, six out of the nineteen substances monitored exceeded their respective Predicted No-Effect Concentrations: azithromycin (34%), imidacloprid (9%), 17β-estradiol (E2) (9%), clarithromycin (7%), ciprofloxacin (7%), and diclofenac (5%); and therefore, their levels could pose an environmental risk.

This work was supported by the Basque Water Agency (URA) through the project “Network for monitoring the ecological and chemical status of transitional and coastal waters of the Basque coast”, and partly by the Generalitat de Catalunya (Consolidate Research Group 2017-SGR-14) and the Ministry of Science and Innovation of Spain (Project CEX2018-000794-S). Biotage is acknowledged for the gift of ISOLUTE® Na2SO4 drying cartridges. The authors acknowledge the help of the entities in charge of the management of the three studied WWTPs (Consorcio de Aguas Bilbao Bizkaia, Consorcio de Aguas de Busturialdea and Aguas del Añarbe), as well as the work of all sampling and laboratory technicians. This is contribution number 1002 from the Marine Research of AZTI-BRTA (Basque Research and Technology Alliance).

Peer reviewed