Total oxygen uptake and TCO2 release from core incubation experiments on marine sediments - Caswell Sub-basin, Browse Basin Marine Survey (GA0345/GA0346/TAN1411)

Full description

Geoscience Australia (GA) conducted a marine survey (GA0345/GA0346/TAN1411) of the north-eastern Browse Basin (Caswell Sub-basin) between 9 October and 9 November 2014 to acquire seabed and shallow geological information to support an assessment of the CO2 storage potential of the basin. The survey, undertaken as part of the Department of Industry and Science's National CO2 Infrastructure Plan (NCIP), aimed to identify and characterise indicators of natural hydrocarbon or fluid seepage that may indicate compromised seal integrity in the region.
The survey was conducted in three legs aboard the New Zealand research vessel RV Tangaroa, and included scientists and technical staff from GA, the NZ National Institute of Water and Atmospheric Research Ltd. (NIWA) and Fugro Survey Pty Ltd. Shipboard data (survey ID GA0345) collected included multibeam sonar bathymetry and backscatter over 12 areas (A1, A2, A3, A4, A6b, A7, A8, B1, C1, C2b, F1, M1) totalling 455 km2 in water depths ranging from 90 - 430 m, and 611 km of sub-bottom profile lines. Seabed samples were collected from 48 stations and included 99 Smith-McIntyre grabs and 41 piston cores. An Autonomous Underwater Vehicle (AUV) (survey ID GA0346) collected higher-resolution multibeam sonar bathymetry and backscatter data, totalling 7.7 km2, along with 71 line km of side scan sonar, underwater camera and sub-bottom profile data. Twenty two Remotely Operated Vehicle (ROV) missions collected 31 hours of underwater video, 657 still images, eight grabs and one core.
This catalogue entry refers to the results (total oxygen uptake rates and carbon dioxide fluxes) of core incubation experiments undertaken on surficial sediments after their extraction from the seafloor.

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Maintenance and Update Frequency: asNeeded

Statement: Two 4.5cm diameter cores of surface sediment overlain by 0.118L of local seawater was incubated in the dark for ~4 hours at ~26oC after a ~3 hour pre-incubation period. Dissolved oxygen levels were measured at ~30 minute intervals using the Presens technology. Samples for DIC analysis were taken at the start and finish of the incubation. Blank cores (local seawater only) accompanied all incubations. Dissolved inorganic carbon concentrations (DIC) were determined using a DIC analyser and infrared-based CO2 detector. (Geoscience Australia). CO2/O2 production/consumption rates were calculated by concentration differences (T=1 T=0) over the incubation period. Accuracy of O2 measurements was ± 0.1 mg L-1. The %RSDs of the precisions and accuracies of the dissolved inorganic carbon analyses were both 0.6%.