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Trace metals in water soluble fraction of marine aerosols

In the frame of the project funded by Croatian science foundation „The Sulphur and Carbon Dynamics in the Sea- and Fresh-water Environment“(SPHERE), we are studying sulphur (S) and carbon (C) dynamics between different environmental compartments (atmosphere, water, sediment, biota) of the sea- and fresh-water environment. A main focus is on distribution between organic, inorganic, dissolved, colloidal and nanoparticulate fraction. Important part of the project is focused on characterization of marine aerosols for the presence of organic, sulphur and trace metal species by electrochemical, chromatographic and ICPMS methods. The atmospheric deposition of mineral dust is one of the most important pathways by which trace metals reach the ocean. Recently, it has been recognized that trace metals such as Fe, Mn, Zn, Cu, Co, and Cd are essential for phytoplankton growth. The fraction of atmospherically deposited trace metals especially iron which dissolves in seawater, or becomes available to phytoplankton for growth, is a key determinant of primary productivity in many open ocean regions. Atmospheric dust concentrations, and hence the dry or wet deposition of dust to the ocean, are highly variable in both space and time but in the context of this discussion are relatively well understood. Much less well constrained is the fraction of the trace metals contained in atmospheric deposition which is soluble in seawater and/or available to marine photosynthetic organisms. The unique, eutrophic, and euxinic marine lake, Rogoznica Lake, in the central Dalmatia is selected as one of the important study site for monitoring of the total deposition fluxes of trace metals to the water column of the lake. This lake is considered as an extreme seawater system which feels all effects of the Adriatic atmospheric and ocean conditions. Influence of these conditions due to the lake semiclosed nature might be several times stronger than in other coastal and open sea Adriatic waters. The aerosol samples (aerodynamic diameter <2.5 μm) were collected on the glass fiber GF/F and teflon filters (φ=47 mm) by low volume sampler (2.3 m3/h, sampling time: 24 h). Trace metals in the water soluble aerosol fraction were measured by ICPMS. In parallel samples surface active substances and reduced sulphur species were characterizated by electrochemical methods, while total and dissolved organic carbon (TOC, DOC) were measured by high temperature catalytic oxidation (HTCO). The first preliminary results will be presented and discussed.

PM2.5 ; trace metals ; marine aerosols ; Adriatic Sea

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