The origin of particulate organic carbon in the marine atmosphere as indicated by its stable carbon isotopic composition

Abstract

Organic carbon concentration and isotopic composition were determined in samples of atmospheric particulate matter collected in 1979 at remote marine locations (Enewetak atoll, Sargasso Sea) during the SEAREX (Sea‐Air Exchange) program field experiments. Atmospheric Particulate Organic Carbon (POC) concentrations were found to be in the range of 0.3 to 1.2µg.m−3, in agreement with previous literature data. The major mass of POC was found on the smallest particles (r<0.5µm). The 13C/12C of the small particles is close to the one expected (δ13C = 26 ± 2‰) for atmospheric POC of continental origin. For all the samples analysed so far, it appears that more than 80% of atmospheric POC over remote marine areas is of continental origin. This can be explained either by long‐range transport of small sized continental organic aerosols or by the production of POC in the marine atmosphere from a vapor phase organic carbon pool of continental origin. The POC in the large size fraction of marine aerosols (<20% of the total concentration) is likely to have a direct marine origin since its carbon isotopic composition is close to the expected value (δ13C = −21 ± 2‰) for POC associated with sea‐salt droplets transported to the marine atmosphere.

Distributions of low molecular weight dicarboxylic acids, ketoacids and α-dicarbonyls in the marine aerosols collected over the Arctic Ocean during late summer

“…The δ 13 C values are relatively small, ranging from −24.7 ‰ to −29.7 ‰ with an average of −26.5 ‰. These low values suggest that the aerosol carbon may be derived from organic matter of terrestrial plant origin (Chesselet et al, 1981;Cachier et al, 1986;Kawamura et al, 2004;Narukawa et al, 2008). Because the surface waters in the Canadian Shelf of the Beaufort Sea are significantly influenced by the freshwater inflow from the Mackenzie River (Carmack et al, 2004), terrestrial organic materials are supplied to the surface ocean and then emitted to the air by bubble bursting processes associated with wind action.…”

Elemental and isotopic characterization of dissolved and particulate organic matter in a unique California upwelling system: Importance of size and composition in the export of labile material

“…(1) the influence of sub-micron aeolian particles in smaller POM with lighter carbon signatures (d 13 C 5 226.5% to 226.7%; Chesselet et al 1981); (2) changes in relative terrestrial OM contribution (Hernes and Benner 2002); or (3) fundamental differences in stable isotopic fractionation between small vs. larger marine unicellular organisms, such that POM size fractions may reflect differences in primary producer community composition (i.e., eukaryotic vs. prokaryotic; Close et al 2011;A. Pearson pers.…”

Transport and diagenesis of dissolved and particulate terrigenous organic matter in the North Pacific Ocean

“…Indications are that the 0.1-0.7 mm size fraction could account for as much as 40-50% of suspended POC Altabet, 1990). Studies have shown that carbon associated with aerosol particles are largely in this size fraction (Hoffman and Duce, 1977;Chesselet et al, 1981) and that the d 13 C of aerosols (À26.5 to À26.7%) over the Pacific and Atlantic Oceans indicate a terrigenous origin (Chesselet et al, 1981). A simple mixing model, in which all particles greater than 0.7-0.8 mm are considered marine with a d 13 C of À22%, and all smaller particles are considered terrestrial with a d 13 C of À27%, results in total particulate d 13 C values more depleted than À24%.…”