First-year sea ice leads to an increase in dimethyl sulfide-induced particle formation in the Antarctic Peninsula

Eunho Jang,Ki-Tae Park,Young Jun Yoon,Kitae Kim,Yeontae Gim,Hyun Young Chung,Kitack Lee,Jinhee Choi,Jiyeon Park,Sang-Jong Park,Ja-Ho Koo,Rafael P Fernandez,Alfonso Saiz-Lopez

doi:10.1016/j.scitotenv.2021.150002

Abstract

Dimethyl sulfide (DMS) produced by marine algae represents the largest natural emission of sulfur to the atmosphere. The oxidation of DMS is a key process affecting new particle formation that contributes to the radiative forcing of the Earth. In this study, atmospheric DMS and its major oxidation products (methanesulfonic acid, MSA; non-sea-salt sulfate, nss-SO42–) and particle size distributions were measured at King Sejong station located in the Antarctic Peninsula during the austral spring–summer period in 2018–2020. The observatory was surrounded by open ocean and first-year and multi-year sea ice. Importantly, oceanic emissions and atmospheric oxidation of DMS showed distinct differences depending on source regions. A high mixing ratio of atmospheric DMS was observed when air masses were influenced by the open ocean and first-year sea ice due to the abundance of DMS producers such as pelagic phaeocystis and ice algae. However, the concentrations of MSA and nss-SO42– were distinctively increased for air masses originating from first-year sea ice as compared to those originating from the open ocean and multi-year sea ice, suggesting additional influences from the source regions of atmospheric oxidants. Heterogeneous chemical processes that actively occur over first-year sea ice tend to accelerate the release of bromine monoxide (BrO), which is the most efficient DMS oxidant in Antarctica. Model-estimates for surface BrO confirmed that high BrO mixing ratios were closely associated with first-year sea ice, thus enhancing DMS oxidation. Consequently, the concentration of newly formed particles originated from first-year sea ice, which was a strong source area for both DMS and BrO was greater than from open ocean (high DMS but low BrO). These results indicate that first-year sea ice plays an important yet overlooked role in DMS-induced new particle formation in polar environments, where warming-induced sea ice changes are pronounced.

Highlights

Dimethyl sulfide (DMS) is mostly of a marine origin and is the largest source of natural sulfur to the atmosphere (Simó, 2001)
The air masses assigned for Antarctic open ocean (AOO) (n = 1983), western Antarctic Peninsula (WAP) (n = 1675), and eastern Antarctic Peninsula (EAP) (n = 1358) showed different origins: AOO mostly originated from the open ocean, while WAP and EAP were characterized by longer air mass exposures to ice-related areas (Fig. 1c)
The WAP and EAP were most exposed to the first-year ice zone during the study period; the WAP had the highest exposure to the first-year ice zone, at 9.1- and 1.5-fold greater than that of the AOO and EAP, respectively

Summary

Introduction

Dimethyl sulfide (DMS) is mostly of a marine origin and is the largest source of natural sulfur to the atmosphere (Simó, 2001). Marine algae metabolize DMSP as a defense mechanism that acts as an osmolyte, cryoprotectant, antioxidant, and predator suppressor (Kirst et al, 1991; Strom et al, 2003; Sunda et al, 2002). The Southern Ocean has a greater potential for DMS and DMSP production during the austral spring–summer period, largely owing to a massive bloom of strong DMS producers (Curran and Jones, 2000; Lana et al, 2011). Sea surface DMS concentrations in the Southern Ocean are estimated to be the highest on the globe, with mean values of >5 nM during the austral spring-summer period (Jarníková et al, 2018; Lana et al, 2011)

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Discussion

Conclusion