engleski

Atmospheric deposition impacts on the sea surface microlayer in the coastal environment

Atmospheric deposition (AD) is an important source of pollutants and nutrients, including trace metals (TM), for surface waters, especially so in oligotrophic areas, which make up for up to 60% of the global ocean. To assess AD impacts of biologically relevant TM (Zn, Cu, Co, Ni, Cd, Pb) on the sea surface responses in an oligotrophic coastal region, while considering the role of the sea surface microlayer (SML), samples of aerosol (PM10), bulk deposition (BD), the SML and underlying water (ULW) were collected during a field campaign at the middle Adriatic between February and July 2019 (HRZZ IP-2018-01-3105 project). Middle Adriatic is part of the Mediterranean Sea, under a combined influence of marine and continental air masses, and high to very high risk of forest fires. Our data show that the three open-fire biomass burning (BB) events recorded caused considerable concentration increases of all PM10 TM, which was reflected in the TM levels and enrichment in the SML samples. Saharan dust intrusion in spring increased Co concentration in PM10 ten times, and strongly affected the Co BD flux. Combined impact of Saharan dust event and three BB events showed that a small number of such extreme events could be responsible for most of the AD in the coastal environment. By our estimation, AD presents a significant source of TM for the shallow middle Adriatic coastal area compared to local riverine inputs, stressing the need to further explore the atmosphere – sea surface links, and deepen our understanding of their biogeochemistry and impacts on the aquatic microbial communities.

Aerosol ; Bulk deposition ; Sea surface microlayer ; Trace metals ; Adriatic sea ; Biomass burning

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