Organic UV filters are used worldwide in various personal care products as well as textiles, paints, plastic, food and adhesives. They are main ingredients in sunscreen lotions that are used heavily by beachgoers in the summer season.There is thus an increasing concern regarding the fate of organic UV filters in the environment and their impact on living organisms. Many of the UV filters in use are hydrophobic and are expected to accumulate in the sediment phase in aquatic systems, but this has yet to be validated in situ. We targeted the UV filters benzophenone 3 (BP3), butyl Methoxydibenzoylmethane (BMDBM), diethylhexyl butamido triazone (DBT), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT) and methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) in a freshwater lake and in a coastal bay in order to understand their distribution during summer 2016. Further, we examined their environmental partitioning by collecting samples from the surface water, the sediment phase and water surface microlayer (SML). We show for the first time the presence of DBT, BEMT and MBBT in environmental matrices (water, SML, and sediment). Notably, these UV filters were detected at low amounts in surface waters with maximum concentrations of 9.9 ng/L for DBT, 18.4 ng/L for BEMT and below detection limits for MBBT, and somewhat higher concentrations in the SML, with maximum concentrations of 43.3 ng/L for DBT, 5625.4 ng/L for BEMT and 45.6 ng/L for MBBT. These filters were detected at even greater concentrations in the sediments, with maximum concentrations of 652.6 ng/g for DBT, 115.0 ng/g for BEMT and 75.2 ng/g for MBBT (dry weight sediment). We also performed controlled laboratory experiments to determine their partitioning behavior and we verified the actual solubility of many of the filters. This will help in determining the environmental fate and finally lead to a better risk assessment of these compounds. Together, these results corroborate the hypothesis that hydrophobic UV filters accumulate in the sediment phase and highlight the importance of discerning whether these UV filters impact the benthic community and their potential for bioaccumulation.

Benzophenone-3 (BP3) is a widely used organic UV filter present in many environmental compartments. One way BP3 is released into the environment is through effluents from wastewater treatment plants (WWTPs). These plants are possible sources for degradation activity as WWTP sludge can potentially degrade BP3. Our goal was to identify the BP3 degrading microorganism(s) in WWTP sludge and to investigate whether the degradation was co-metabolic. Initial WWTP sludge microcosms spiked with BP3 showed 100% degradation after 20 days. Multiple 2 transfers of these microcosms, while maintaining a strong selective pressure for BP3 degradation capabilities, resulted in the dominance of one bacterial strain. This strain, Sphingomonas wittichii BP14P was subsequently isolated and shown to degrade BP3 in a growth dependent manner. Strain BP14P utilized BP3 as the sole energy and carbon source and completely degraded BP3 after 7 days in minimal media. We tested the capability of BP14P to degrade nine other UV filters, but the degradation ability seemed to be restricted to BP3. However, whether this specificity is due to the lack of degradation genes, cellular transport or low bioavailability of the other UV filters remained unclear. The efficient degradation of BP3 by a group of bacteria well known for their potential for xenobiotic degradation is an important step forward for a complete risk assessment of the long-term environmental impact of BP3.