Suscreen components in coastal marine watersenvironmental implications

Résumé

1. A new procedure for the analysis of titanium by MSFIA-LWCC previous digestion with K2S2O8 in coastal seawater, marine sediments and marine macrophytes has been developed. The method implies low consumption of reagent, good linearity (up to 1 μM), limit of detection (9.2 nM) and quantification (30.8 nM) respectively and high repeatability (RSD of 1.8 %). 2. Concentrations of organic UV-filters (i.e. BZ-3 and 4-MBC) have been quantified in coastal marine waters. 3. Organic and inorganic compounds included in the formulation of sunscreen are enriched in the sea surface microlayer. 4. Under solar radiation commercial sunscreens produce significant amounts of hydrogen peroxide in seawater, a strong oxidizing agent that generates high levels of stress on marine phytoplankton. 5. Photoexcitation of inorganic UV-filters (i.e. TiO2 and ZnO nanoparticles) are the main responsible of hydrogen peroxide production in the shallow water of touristic beaches. Hydrogen peroxide concentrations are enriched in the surface microlayer and near the sediments. 6. Sunscreens have a negative effect on the growth of the marine diatom Chaetoceros gracilis. EC50 calculated for different sunscreen ranged between 45 ± 2 mg L-1 for spray sunscreen to 218 ± 17 mg L-1for solar milk. 7. Conservative estimation for a Mediterranean beach reveals that tourist activities during a summer day may release the amount of 4 Kg of TiO2 nanoparticles to the water and produce an increment on the concentration of H2O2 of 270 nM per day. 8. Results presented here, together with the data provided by tourism records in the Mediterranean, point to sunscreen as an important pollutant to coastal waters, with direct ecological consequences to the ecosystem.