Presence and Distribution of Sun-Blocking Agents in the Danube River: Implications for Aquatic Ecosystem Health

Organic sun-blocking agents are recognized as emerging pollutants of the aquatic environment. The consequences and effects of these harmful substances on aquatic organisms are not fully understood, particularly in the context of Romania. This study examines the presence and environmental hazards posed by ten UV filters found in the Danube River. Six of the ten targeted contaminants were detected in surface water samples: 2-hydroxy-4-methoxy-benzophenone (BP-3), 2,4-dihydroxy benzophenone (BP-1), 2,3,4-trihydroxy benzophenone (234HBP), 2,2′-dihydroxy-4-methoxy-benzophenone (BP-8), 2-hydroxy-4-methoxy-4′-methyl-benzophenone (BP-10), and benzyl salicylate (BS). In sediment samples, seven of the ten compounds were identified: BS, BP-3, 4-hydroxybenzophenone (4HBP), BP-1, 234HBP, 2,2′,4,4′-tetrahydroxybenzophenone (BP-2), and BP-10, with different frequencies. The correlation coefficients showed strong relationships between benzophenone derivatives in surface water samples and a common contamination source for BP-3 and BS in sediment samples. In the assessment, the risk quotient (RQ) for BP-1 in fish was determined to be 1.81. Similarly, RQ values for BP-3 were calculated as 1.24 for Daphnia magna and 57 for fish, suggesting that these UV filters could potentially present substantial hazards to the aquatic ecosystem. The study findings indicate that additional research is needed to investigate the presence and potential risks of organic sun-blocking agents in surface waters, with a particular emphasis on densely populated areas in Romania.