Base de données de recherche des TNO

étiquettes: physical sciences, geology, hydrocarbon exploration

Objectif(s): To ascertain the formation of marine pock marks, which are circular depressions on the sea floor thought to have formed from the release of methane gas.

Description du projet: The research goals are to ascertain the formation of marine pock marks, 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 the release of methane from degrading or thawing offshore permafrost. The research team intend to document the sea bed characteristics, measure gas release and water column properties and to ascertain if any unique marine habitat are associated with the pock mark features. This research will take place onboard a ~50’ long private research vessel called the Ukpik (https://rvukpik.com/) from Prudhoe Bay Alaska. This vessel was chosen as it has shallow draft and will be brought to the area by Alaskan and Canadian researchers studying bowhead whales. 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 also do some research while travelling to and from Tuktoyaktuk to assist with mapping the marine approaches to Tuktoyaktuk Harbour. Bathymetric surveys to map sea bottom and water column will be conducted. A shallow water pole mounted multibeam sounder will be used to map the bottom morphology and detect evidence of gas discharge. This equipment is being provided by the Canadian Hydrographic Service and is used routinely by Fisheries and Oceans Canada for bottom mapping. Remotely Operated Vehicle (ROV) Surveys will be conducted. On an opportunity basis the research team will conduct remotely operated vehicle (ROV) dives to photograph the sea bottom and gas discharges. The ROV is powered via an umbilical from a small generator on the ship. The ROV is small with dimensions of ~30 cm x 30 cm x 20 cm. Water Sampling will be conducted. Sea water samples (~50 samples, each less than 1 litre in size) will be collected using a small water sampling (conductivity, temperature, and depth) CTD rosette at various locations within the study area. The rosette will document water column characteristics and capture sea water samples for later analysis, including methane concentration. Sea floor moorings will be deployed. The research team will deploy small oceanographic moorings to monitor changes in the water column that could be caused by gas or fluid release. These electronic devices are deployed on a small anchor and retrieved after the period of investigation. The anchor (a small steel plate or links of heavy chain) will be left on the sea floor. The teamanticipate most of the moorings will be retrieved after the one week field program, however two moorings may be left on site and retrieved next summer. The moorings will be within 50 cm of the sea bottom in 9 to 20 m water depths. Aurora Research Institute (ARI) technician will participate in the program. Research team will be based and provisioned in Tuktoyaktuk. Copies of publications will be provided to ARI and the communities through the Hunters and Trappers Committees. The fieldwork for this study will be conducted from August 17, 2018 to September 2, 2018.