Base de données de recherche des TNO

étiquettes: physical sciences, sediment chemistry, bathymetry, methane, seabed mapping

Objectif(s): To ascertain the formation of marine pockmarks, document the seabed characteristics, measure gas release and water column properties and to ascertain if any unique marine habitat are associated with the pockmark features.

Description du projet: The goals of this research are to ascertain the formation of marine pockmarks, which are circular depressions on the sea floor thought to have formed from the release of methane gas. The hypothesis is that these features are actively releasing gas to the atmosphere and that they are formed from degrading or thawing offshore permafrost. The research team intend to document the seabed characteristics, measure gas release and water column properties and to ascertain if any unique marine habitat are associated with the pockmark features. This research will take place onboard a 29 m long Parks Canada research vessel called the RV David Thompson. The science team will embark and disembark the vessel in Tuktoyaktuk for a 5-7 day marine research program. This work builds on marine research expeditions onboard the Canadian Coast Guard vessel Sir Wilfrid Laurier conducted in 2010, 2012, 2013 and 2016.Summaries of the geohazard research in the Beaufort Sea was presented to the Inuvialuit Game Council in March 2019. The Kugmallit Pock Mark Field is located approximately 35 km northwest of Tuktoyaktuk (69° 45'N, 133° 21.5'W), outside of the Kittigaryuik Marine Protected area. The research team will concentrate the studies in this area, but will also do some research while travelling to and from Tuktoyaktuk to assist with mapping the marine approaches to Tuktoyaktuk Harbour. The research team will conduct bathymetric surveys to map sea bottom and water column. A shallow water hull-mounted multibeam echo-sounder system will be used to map the bottom morphology and detect evidence of gas discharge. The pockmarks were previously surveyed in 2004, 2005, and 2008. The goal of this survey will be to detect change and provide a basis to assess the activity of the features. The team will also map the occurrence of gas plumes in the water column. On an opportunity basis, the team will conduct remotely operated vehicle (ROV) dives to photograph the sea bottom and gas discharges. The small ROV is powered via an umbilical from a small generator on the vessel. Sea water samples (~50 samples, each less than 1 litre in size) will be collected using a small water sampling CTD rosette at various locations within the study area. The rosette will document water column characteristics and capture seawater samples for later analysis, including methane concentration Seafloor sediment samples will also be collected (~5 samples, each ~10 cm in diameter x 30 cm in length) using a small coring device deployed from the vessel to document sediment properties. An instrument will be installed on the mast of the vessel to continuously measure methane concentrations in the air. Methane concentrations in the seawater will also be measured through a continuous intake. The sea water flows through the instrument, the measurement is taken, then the water returns to the ocean. Copies of publications will be provided to Aurora Research Institute and the communities through the Hunters and Trappers Committees. The research team are also planning a community science day in Tuktoyaktuk for August 1, 2019 in conjunction with other federal and territorial government departments, the Aurora Research Institute and the Hamlet office. The team hope this will be a venue for many researchers who work in the Tuktoyaktuk area to share their research with the community. The fieldwork for this study will be conducted from July 25, 2019 to August 6, 2019.