Tracing water-soluble, persistent substances in the Black Sea

Area of Science:

• Environmental Chemistry
• Oceanography
• Water Quality Modeling

Background:

• Persistent organic pollutants (POPs) pose risks to marine ecosystems.
• Understanding the fate of water-soluble POPs in the Black Sea is crucial for environmental management.
• Previous studies have focused on bioaccumulative substances, leaving knowledge gaps for non-bioaccumulative POPs.

Purpose of the Study:

• To simulate the transport and fate of water-soluble, non-bioaccumulative persistent substances in the Black Sea.
• To establish a correlation between the degradation half-life (DT50) and average concentration of these substances.
• To estimate the DT50 and riverine concentrations of specific pharmaceuticals and pesticides in the Black Sea.

Main Methods:

• Coupling a tracer model with a 3D circulation model to simulate pollutant transport.
• Utilizing specified degradation times and riverine concentrations to build concentration-DT50 correlations.
• Performing simulations from 2000 to 2019 with real atmospheric forcing and river runoff data.
• Validating model estimates using existing observational data for specific compounds.

Main Results:

• A clear exponential dependence was found between average Black Sea concentration and DT50.
• Seasonal cycles were observed in average shelf concentrations, but not in deep-water concentrations.
• Estimated DT50 and riverine concentrations for carbamazepine, sulfamethoxazole, and terbuthylazine.
• Evidence suggests long-term accumulation of atrazine and simazine due to slow degradation.

Conclusions:

• The developed model effectively predicts the distribution of water-soluble persistent substances based on their DT50 and riverine input.
• The findings highlight the importance of considering degradation rates in assessing the environmental risk of POPs.
• Specific pharmaceuticals and pesticides are identified as contaminants of concern in the Black Sea, requiring further monitoring and management strategies.