DMS emissions from the Arctic marginal ice zone

Abstract

Phytoplankton blooms in the Arctic marginal ice zone (MIZ) can be prolific dimethylsulfide (DMS) producers, thereby influencing regional aerosol formation and cloud radiative forcing. Here we describe the distribution of DMS and its precursor dimethylsulfoniopropionate (DMSP) across the Baffin Bay receding ice edge in early summer 2016. Overall, DMS and total DMSP (DMSPt) increased towards warmer waters of Atlantic origin concurrently with more advanced ice-melt and bloom stages. Relatively high DMS and DMSPt (medians of 6.3 and 70 nM, respectively) were observed in the surface layer (0–9 m depth), and very high values (reaching 74 and 524 nM, respectively) at the subsurface biomass maximum (15–30 m depth). Microscopic and pigment analyses indicated that subsurface DMS and DMSPt peaks were associated with Phaeocystis pouchetii, which bloomed in Atlantic-influenced waters and reached unprecedented biomass levels in Baffin Bay. In surface waters, DMS concentrations and DMS:DMSPt ratios were higher in the MIZ (medians of 12 nM and 0.15, respectively) than in fully ice-covered or ice-free conditions, potentially associated with enhanced phytoplanktonic DMSP release and bacterial DMSP cleavage (high dddP:dmdA gene ratios). Mean sea–air DMS fluxes (µmol m–2 d–1) increased from 0.3 in ice-covered waters to 10 in open waters (maximum of 26) owing to concurrent trends in near-surface DMS concentrations and physical drivers of gas exchange. Using remotely sensed sea-ice coverage and a compilation of sea–air DMS flux data, we estimated that the pan-Arctic DMS emission from the MIZ (EDMS, MIZ) was 5–13 Gg S yr–1. North of 80°N, EDMS, MIZ might have increased by around 10 ± 4% yr–1 between 2003 and 2014, likely exceeding open-water emissions in June and July. We conclude that EDMS, MIZ must be taken into account to evaluate plankton-climate feedbacks in the Arctic.

Variability of dimethyl sulphide (DMS), methanethiol and other trace gases in context of microbial communities from the temperate Atlantic to the Arctic Ocean

“…Previously reported DMS levels in polar oceans varied between 3 to 18 nM (Mungall et al, 2016;Jarníková et al, 2018;Uhlig et al, 2019), with up to 74 nM in the sub-surface Chl a maximum of the Baffin Bay (Galí et al, 2021). Hence, these are overall in the same range as our values.…”

Marine biogenic emissions of benzene and toluene and their contribution to secondary organic aerosols over the polar oceans

“…A total of 24 depth profiles were measured during this deployment. In the marginal ice zone in summer and spring, the sea ice cover controls the biogeochemistry and the physical structure of the water column, including the distribution of Chl a and density (48) as well as bacterial activity (49). Thus, exactly as in Wohl et al (50), vertical profiles were classified by sea ice cover (SIC) at the time of sampling (Figure 3).…”

Data-driven exploration of the variability, controls and future changes of dimethyl sulfide in the global surface ocean

“…In addition, both seasonal and decadal observations showed that enhanced Atlantification led to an increase in the summertime proportion of Phaeocystis pouchetii and decrease of diatoms (Nöthig et al, 2015;Orkney et al, 2020;Reigstad et al, 2002). Phaeocystis is likely one of major contributors to dimethylated sulfur compounds at high latitudes (Galí et al, 2021). Therefore, the close link between major DMSP-producing phytoplankton and saline Atlantic waters may partly explain why the SSS is a key influencing factor of the spatiotemporal variations of DMS in the Arctic region.…”

“…Therefore, the close link between major DMSP-producing phytoplankton and saline Atlantic waters may partly explain why the SSS is a key influencing factor of the spatiotemporal variations of DMS in the Arctic region. It should be noted that salinity change and water stratification caused by sea-ice melt may also affect phytoplankton biomass and community structure (Ardyna and Arrigo, 2020;Galí et al, 2021), but the specific influence of sea-ice melt on DMS remains to be studied. Our results show that the coastal and Arctic regions belong to bloom-forced regime for DMS cycling, which is consistent with previous statements (Toole and Siegel, 2004).…”