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.

Onshore research was conducted using the following methods: multi-temporal analysis and mapping of modern and raised coastal systems using airphotos, satellite imagery, LiDAR and RTK GPS surveys. Data on the sediment composition of coastal landforms was collected using graded photographs and in situ measurments of gravel samples. Shallow-water mapping of transgressive coastal systems was carried out using multibeam sonar and sub-bottom profiler primarily from the CCGS Amundsen (EM300 30 kHz) and the CSL Heron (EM3002 3.5 kHz) during the 2006 ArcticNet NCE scientific cruise and from the CCGS Henry Larsen and the CSL Heron in 2008.

Onshore research was conducted using the following methods: multi-temporal analysis and mapping of modern and raised coastal systems using airphotos, satellite imagery, LiDAR and RTK surveys. Data on the sediment composition of coastal landforms was collected using graded photographs. Shallow-water mapping of transgressive coastal systems was carried out using multibeam sonar and sub-bottom profiler primarily from the CCGS Amundsen and the CSL Heron during the 2006 ArcticNet NCE scientific cruise.

In 2017 and 2018, we sampled about 20 locations across Frobisher Bay, mostly in the deeper portions of outer Frobisher Bay that are only accessible for sampling from large ships. Sample stations were chosen to span the range of depth and slope values in the multibeam sonar dataset, and in 2018 sampling, also included gross bottom morphology, such as ridges and troughs. We also targeted some particular geomorphic features, such as suspected submarine extensions of moraines. In 2017, bottom samples were acquired using box-cores, and small scientific trawl (Agassiz trawl). In 2018, bottom samples were acquired using box-cores, combined with a drop-video camera. Agassiz trawls were collected at two stations in 2018. Sediment samples were described visually and subsamples frozen for grain size and organic content analysis. Where informative, subsamples of lithic fragments within the sediments were kept for mapping. Bottom faunal samples were enumerated and preserved in 2% formalin in seawater, except for larger faunal samples such as soft corals, which were frozen.

Air, water (grab and passive) and sediment samples were collected from on board the CCGS Amundsen in the summer of 2015 as a part of ArcticNet and the Northern Contaminants Program. These samples were collected to determine the occurrence and levels of legacy pesticides and new and emerging priority compounds under the Canadian Chemical Management Plan.

To obtain the data, water samples of vertical profiles were firstly collected from the Rosette onboard the CCGS Amundsen, and then analyzed with instruments both onboard and in the lab in University of Manitoba. The total mercury were measured on a Tekran 2600 Model with the method EPA 1631 in the Portable In-situ Laboratory for Mercury Species onboard, while the methylmercury data were analyzed with the method EPA 1630 in the Ultra-Clean Trace Element Laboratory, which is located at the University of Manitoba. The main data types are the contaminants (along with O18 isotopes and dissolved organic carbon) concentrations in vertical profiles at the study sites.

The surface temperature of the target within the passive microwave (PMW) systems field of view were collected on a high temporal resolution. An infrared transducer was positioned on the port side of the CCGS Amundsen, at a height of approximately 7 meters. Data collection occurred every 15 seconds. The instrument collected data throughout the entirety of the Amundsen Cruise at a fixed angle. Brightness temperature data of target is in degrees Celsius.

Bottom water (20 L per station) was collected at 11 stations in Baffin Bay using the CCGS Amundsen’s rosette system. Water was filtered aboard the vessel into glass microfiber (GF-F) filters for Carbon and Nitrogen stable isotopic composition analysis. These data will be used in combination with data on soft coral stable isotopic composition collected from the same region.

Agassiz trawl was deployed from the CCGS Amundsen to collect macrofauna. Catches were passed through a 2 mm mesh sieve. When possible, specimens were identified to the lowest taxonomic level, then count and weight. The unidentified specimens were preserved in a 4% seawater-formalin solution. Box corer was deployed to quantitatively sample diversity, abundance and biomass of infauna and to sample sediment. Sediments of a surface area of 0.125 m2 and 10-15 cm in depth were collected and sieved through a 0.5 mm mesh and preserved in a 4% formaldehyde solution for further identification in the laboratory. Sub-cores of sediments were collected for sediment pigment content, organic matter, sediment grain size, porosity; for sediment pigments, the top 1 cm was collected, although for sediment grain size, the top 5 cm was collected. Sediment pigment samples were frozen at -80°C, and porosity, organic matter and sediment grain size samples were frozen at -20°C.

We collected air, water, sediment samples in the summer of 2019 from on board the CCGS Amundsen in the central and eastern Canadian Archipelago. We also collected air and water (grab and passive) from the CCGS Laurier in the Beaufort Sea and the R/V William Kennedy in the western Hudson Bay and Chesterfield Inlet. Air samples were continuously collected form the very front of the bow of the ship to reduce contamination from the smoke stack. The air sampler consisted of a filter to collect the particulate followed by a cartridge containing a sandwich of polyurethane foam and XAD resin to sorb the gas phase. Several types of water samples were collected: target compounds were concentrated from grab surface samples (200-L) by filtering through a column of XAD resin. Grab samples for flame retardants were collected in glass bottles and shipped back to the lab for processing. Grab samples for per-fluorinated compounds were collected at the surface and at two-three depths in plastic bottles and shipped back to the lab for processing. Sediment samples were collected from the box corer, the top 0-5cam was collected. Samples were frozen and shipped back to the lab for processing.