North Atlantic marine organic aerosol characterized by novel offline thermal desorption mass spectrometry approach: polysaccharides, recalcitrant material, secondary organics

Abstract

<jats:p>Abstract. The composition of organic compounds in marine aerosols and the relative contributions of primary and secondary organic compounds remain uncertain. We report results from a novel approach to characterize and quantify organic components of the marine aerosol. Size-segregated discrete aerosol filter samples were collected at sea in the North Atlantic from both ambient aerosol and artificially generated primary sea spray over four cruises timed to capture the seasonal phytoplankton bloom dynamics. Samples were analyzed by Fourier transform infrared spectroscopy (FTIR), extracted into water, and analyzed by offline thermal desorption chemical ionization mass spectrometry (TDCIMS) and ion chromatography (IC). A positive matrix factorization (PMF) analysis identified several characteristic aerosol components in the TDCIMS mass spectra. Among these is a “polysaccharide factor” representing about 10–30 % of the submicron organic aerosol mass. An unquantified “recalcitrant factor” of highly thermally stable organics showed significant correlation with FTIR-measured alcohol groups, consistently the main organic functional group associated with sea spray aerosol. We hypothesize that this factor represents recalcitrant dissolved organic matter in seawater. The recalcitrant factor showed little seasonal variability in its contribution to primary marine aerosol. The relative contribution of polysaccharides was highest in late spring and summer in the smallest particle size fraction characterized ( </jats:p>

Seasonal Differences in Submicron Marine Aerosol Particle Organic Composition in the North Atlantic

“…The aMA OM concentrations were not statistically different between seasons (p 0.01 and Supplementary Table 9), but the maximum value was observed in Winter (0.30 ± 0.22 µg m −3 , n = 8) and the minimum in Early Spring (0.1 µg m −3 , n = 1) (Table 1). Hydroxyl group concentrations were strongly correlated (r = 0.9) with Na concentrations obtained from thermal desorption chemical ionization mass spectrometry (TDCIMS) (Lawler et al, 2020;Saliba et al, 2020). This finding supports the interpretation that the hydroxyl group is from a marine source (Bahadur et al, 2010;Russell et al, 2010Russell et al, , 2011Frossard et al, 2014).…”

New Insights Into the Composition and Origins of Ultrafine Aerosol in the Summertime High Arctic

“…On average, about half of the sampled Aitken mode mass could be quantified with calibrated species. The unaccounted-for mass likely includes compounds to which the TDCIMS is less sensitive, for example, non-polysaccharide primary marine organic aerosol (Lawler et al, 2020), but it could also partly arise from uncertainties in particle shape, density, and collection efficiency, or an overestimate of SOA sensitivity (see Text S1.1 in Supporting Information S1).…”