Ecological Risk Dynamics of Pharmaceuticals in Micro-Estuary Environments

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Estuarine Ecology

Background:

• Micro-estuaries (<1 km² surface area) are common in Mediterranean regions and highly susceptible to chemical pollution.
• Fluctuating flow conditions, influenced by wastewater and non-point-source pollution, create dynamic risk regimes in these systems.
• Ecological services in micro-estuaries are compromised due to continuous exposure to various pollutants.

Purpose of the Study:

• To investigate the occurrence and ecological risks of pharmaceutical contamination in the Alexander micro-estuary, Israel.
• To analyze how flow conditions (base flow vs. flood events) affect pharmaceutical composition and concentrations.
• To assess the risk posed by detected pharmaceuticals to different trophic levels within the ecosystem.

Main Methods:

• A two-year monitoring study was conducted in the Alexander micro-estuary.
• Pharmaceuticals were quantified in water samples collected during base flow and flood events (n=280).
• Risk quotients (RQ) were calculated for fish, crustaceans, and algae to evaluate ecological risk.

Main Results:

• Pharmaceuticals were detected in all samples, with concentrations up to 18 μg L⁻¹ during floods and 14 μg L⁻¹ during base flow.
• Carbamazepine dominated base flow samples, while caffeine was more prevalent during flood events.
• Median annual risk quotients indicated high risk to fish (19.6), crustaceans (5.2), and algae (4.5), with ibuprofen, carbamazepine, and caffeine being major contributors.

Conclusions:

• Micro-estuaries like the Alexander estuary face continuous pharmaceutical exposure, posing a significant ecological risk.
• Pharmaceutical contamination levels and composition vary with hydrological conditions, highlighting the impact of pollution sources.
• These findings underscore the elevated vulnerability of micro-estuaries to pollution compared to larger estuarine systems.