Base de données de recherche des TNO

étiquettes: physical sciences, water quality, sediment quality, sonar survey, remediation, invertebrates

Objectif(s): To refloat and remove the Tarsuit Caissons from Lease Area 117/D11-3-7, and to conduct a side scan survey and macro invertebrate survey of the affected site and adjacent area.

Description du projet: The objective of this project is to refloat and remove the Tarsuit Caissons from Lease Area 117/D11-3-7. Following their removal, the research team will conduct the following evaluation of the affected site and adjacent area: 1) Side Scan Survey 2) Macro invertebrate Survey A sidescan/multibeam unit (Edgetech 6205, or similar) will be pole mounted on the bathymetry vessel and data will be collected at a frequency of 550kHz, and dual sidescan sonar at 550kHz. The vessel would travel along designated survey lines spaced so that both the sidescan and multibeam data swaths would be overlapped to get 100% bottom coverage. Data products would be geo-referenced images and gridded XYZ point data of the compiled swath bathymetry data and sidescan sonar mosaic, and geo-referenced image of the compiled sidescan sonar swaths. The sampling program will include the collection of physical habitat data, in-situ water chemistry data and benthic invertebrate community data. Sample sites will include: •One site in each of the 3 out of 4 caisson depressions (3 sites x 3 subsamples = 9 samples) •Three sites in the lease area adjacent to the depressed areas (3 sites x 3 subsamples = 9 samples) Sediment samples will be collected at each site and analyzed for particle size and organic content. Water chemistry profiles for temperature, pH, conductivity, dissolved oxygen and salinity will be collected at each site, along with water depth measurements and general field observations. These data will be used to assess any differences in physical habitat which may affect the distribution of benthic invertebrates. A Van Veen grab enclosing an area of 0.1 m2 will be used to collect benthic invertebrate and sediment samples. This sampler will provide consistency of data with the data collected in 2016. Three field subsamples will be collected at each site for benthic invertebrates, while a composite of three subsamples will be collected at each site for sediment analysis. Samples will be taken with care to minimize the amount of washout, shock waves and substrate disturbance. Only Van Veen grabs that are completely closed and have no loss of sediment will be accepted as a sample. Detailed field notes and photographs will be taken. The samples collected for benthic invertebrates will be sieved in the field using a 0.5 mm mesh sieve. The sieve contents will be transferred to sample containers and preserved in 5 - 10% by volume buffered formalin solution for subsequent laboratory processing. Following approximately 7 days of fixation in formalin, samples will be transferred to 70% ethanol for sample processing. Sample processing will include taxonomic identification and enumeration and will be conducted by qualified professionals from an accredited laboratory with Arctic experience. Marine Mammal Observers will ensure activities do not interfere with marine mammal movement, behavior and feeding activities. Wildlife Monitors ensure safety of program personnel in the instance of a wildlife encounter. ConocoPhillips Canada expects to provide a debrief of the 2017 caisson removal program including the results of the side scan and benthic surveys, to communities in the fall/winter of 2017. Team members will be available to respond to questions face-to-face during the community meetings, and by telephone or email outside of this period. The fieldwork for this study will be conducted from June 15, 2017 to October 31, 2017.