Micro-estuarine ecosystems have a surface area of less than 1 km² and are abundant in Mediterranean regions. Due to their small size, these systems are particularly vulnerable to the effects of chemical pollution. Fluctuating flow conditions, base flow dominated by treated wastewater effluents and flood events transporting rural and urban non-point-source pollution, place micro-estuaries under a dynamic risk regime, making it harder for them to provide ecological services. This two-year study explored the occurrence and risks of pharmaceutical contamination in the Alexander micro-estuary in Israel. Pharmaceuticals were detected in all samples (n = 280), at concentrations as high as 18 µg/L in flood events and 14 µg/L in base flow.
The pharmaceutical mixture composition was affected by flow conditions, with carbamazepine dominating base flow and caffeine dominating flood events. The median annual risk quotients for fish, crustaceans, and algae were 19.6, 5.2, and 4.5, respectively, indicating that pharmaceuticals pose a high risk to the ecosystem. Ibuprofen, carbamazepine, and caffeine contributed most to the risk quotients.
This work highlights that micro-estuary ecosystems, like the Alexander estuary, are continuously exposed to pharmaceuticals and most likely to other pollutants, placing these ecologically important systems at elevated risk compared to the more frequently studied large estuarine systems.
Citation: Topaz, T., Boxall, A., Suari, Y., Egozi, R., Sade, T., & Chefetz, B. (2020). Ecological risk dynamics of pharmaceuticals in micro-estuary environments. Environmental Science & Technology, 54, 11182–11190. https://doi.org/10.1021/acs.est.0c02434