Enrichment of organic pollutants in the sea surface microlayer (SML) at Terra Nova Bay, Antarctica: influence of SML on superficial snow composition

Abstract

Concentrations of dissolved and particle-associated n-alkanes, phthalates and polycyclic aromatic hydrocarbons (PAHs) were measured in sea surface microlayer (SML) and sub-surface water (SSL) samples collected in the coastal area of Terra Nova Bay, Antarctica, during the Austral spring 1998/1999. SML concentrations of the selected organic compounds were higher than SSL values and the enrichment factors were greater in the particulate phase than in the dissolved phase. During the same campaign, “fresh” snow samples, collected at different altitudes (from sea level up to 2670 m) near the coast on Mt Melbourne, immediately after a snowy event, were analysed in order to provide more information on air/sea exchange processes. The same classes of organic compounds found in sea water were also present in “fresh” snow samples. The surfactant fluorescent organic matter (SFOM), adsorbed on the microdrop aerosol surface, could be considered the main constituent of the enrichment and the carrier at higher altitudes of organic compounds. In fact, hydrocarbons (n-alkanes and PAHs), which are not surfactants like phthalates, could interact with SFOM and follow the same fate.