Observational evidence for the formation of DMS-derived aerosols during Arctic phytoplankton blooms

Ki-Tae Park,Sehyun Jang,Kihong Park,Jung-Ho Kang,Kyung-Hoon Shin,Bang-Yong Lee,Kitack Lee,Min-Seob Kim,Young Jun Yoon,Hee-Joo Cho,Roberto Udisti

doi:10.5194/acp-17-9665-2017

Abstract

Abstract. The connection between marine biogenic dimethyl sulfide (DMS) and the formation of aerosol particles in the Arctic atmosphere was evaluated by analyzing atmospheric DMS mixing ratio, aerosol particle size distribution and aerosol chemical composition data that were concurrently collected at Ny-Ålesund, Svalbard (78.5° N, 11.8° E), during April and May 2015. Measurements of aerosol sulfur (S) compounds showed distinct patterns during periods of Arctic haze (April) and phytoplankton blooms (May). Specifically, during the phytoplankton bloom period the contribution of DMS-derived SO42− to the total aerosol SO42− increased by 7-fold compared with that during the proceeding Arctic haze period, and accounted for up to 70 % of fine SO42− particles (< 2.5 µm in diameter). The results also showed that the formation of submicron SO42− aerosols was significantly associated with an increase in the atmospheric DMS mixing ratio. More importantly, two independent estimates of the formation of DMS-derived SO42− aerosols, calculated using the stable S-isotope ratio and the non-sea-salt SO42− ∕ methanesulfonic acid ratio, respectively, were in close agreement, providing compelling evidence that the contribution of biogenic DMS to the formation of aerosol particles was substantial during the Arctic phytoplankton bloom period.

Highlights

Aerosols are known to have influenced the Earth’s radiation budget by scattering and absorbing incoming solar radiation or forming cloud condensation nuclei (CCN) (Charlson et al, 1992; Haywood and Boucher, 2000)
45 % of the variability in the 3-day mean concentrations of nucleation-mode particles can be explained by overall variations in the concentrations of dimethyl sulfide (DMS) and methanesulfonic acid (MSA); some of the remaining variability will be associated with variations in the intensity of solar radiation, which influences the efficiency of photochemical oxidation of DMS
As all chemical species that are directly involved in the nucleation process were not measured during the observational periods of the present study, we are unable to pinpoint the major contributor; these strong correlations between DMS and small aerosol particles indicate that these newly formed particles were probably derived from recently released biogenic DMS

Summary

Introduction

Aerosols are known to have influenced the Earth’s radiation budget by scattering and absorbing incoming solar radiation or forming cloud condensation nuclei (CCN) (Charlson et al, 1992; Haywood and Boucher, 2000). Large uncertainty remains in assessing the effects of aerosols on radiative forcing (IPCC, 2013). Both field and laboratory studies have indicated that sulfate (SO24−) is an aerosol component that principally contributes to the formation of CCN (Kulmala, 2003; Boy et al, 2005; Sipilä et al, 2010). Most SO24− particles originate from three sources: anthropogenic SOx, seasalt SO24−, and marine biogenic emissions (biogenic SO24−). The last of these is exclusively produced from the oxidation of dimethyl sulfide (DMS) (Simó, 2001).

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