Fine-scale time series of surface dimethylsulfide concentrations across ice-covered and ice-free waters of the Canadian Arctic Archipelago in summer, 2017
Ship: CCGS Amundsen CA
Principal Investigator: Levasseur, Maurice
Start Date: 12-07-2017
End Date: 16-08-2017
Citation: Levasseur, M., St-Onge, J., Lizotte, M., Massé, G. and Tremblay, J-E (2018). Fine-scale time series of surface dimethylsulfide concentrations across ice-covered and ice-free waters of the Canadian Arctic Archipelago in summer, 2017. Canadian Cryospheric Information Network (CCIN). Unpublish data.
Abstract: This study presents sea surface concentrations of marine dimethylsulfide (DMS) measured across the Labrador Sea and the Canadian Arctic Archipelago during summer of 2017 (July-August). Using a novel automated instrument (ACT-MIMS) more than 2500 DMS observations were collected at high frequency alongside ancillary measurements of salinity, temperature, fluorescence (chlorophyll a proxy), solar radiation, ice concentration and the algal precursor of DMS, dimethylsulfoniopropionate. DMS concentrations ranged from ca. 1 to 32 nmol L-1 (average of 6 nmol L-1) in 2017 over an area covering a wide range of contrasting marine environments from coastal to open ocean, ice-free waters, as well as under-ice waters. Surface water DMS hotspots were measured in association with thermohaline oceanographic features in high productivity coastal waters, as well as with the presence of ponded first-year ice (FYI). Nighttime increases and daytime decreases of DMS concentrations were also observed in productive areas of the Labrador Sea and Davis Strait continental shelf. The association of DMS concentrations with diurnal solar radiation variation suggests the involvement of photobiological processes. Overall, our results strengthen the view that aqueous DMS cycling in the Arctic is intimately linked with sea ice dynamics and physiological responses to light. As such, future changes in the seasonality of the Arctic cryosphere will likely play an important role in shaping DMS emissions, although the sign and magnitude of the change remain highly uncertain. The objective of this project is to characterize the distribution of oceanic dimethylsulfide (DMS) on a large scale and to link it with the physicochemical and biological parameters of the environment as well as the dynamics of the ice (type, spatial coverage, presence of pond cast iron on the surface). The development of a high-resolution continuous measurement instrument and its deployment aboard the CCGS Amundsen will significantly improve the spatial and temporal resolution of DMS measurements in different contrasting environments (open water, under and around the ice pack, coastal environments) of the Canadian Arctic. Ancillary data for salinity, surface temperature, fluorescence (chlorophyll a proxy), O2 / Ar ratio (net community production proxy) as well as composite images at 360oC contiguous to the vessel and satellite images of the canopy cover ice, will be exploited.