The CANYONS voyage on RV Investigator aimed to investigate past and present processes governing the flow pathways, formation and geochemical signatures of Antarctic Bottom Water (AABW) off Cape Darnley, East Antarctica. The proposed survey area was focussed on the Wild and Daly canyons and the adjacent sediment drifts - the Daly and ‘Armand’ drifts. The survey aimed to collect systematic multibeam bathymetry and sub-bottom profiles across the region to support collection of long sediment cores (up to 24 m), Kasten cores and multicores, CTDs (conductivity- temperature-depth instruments) and deep towed camera transects This dataset reports analyses of samples collected from the surface uncontaminated "underway" seawater supply on R/V Investigator. The samples were collected while the ship transited from Perth to Cape Darnley. A suite of samples were collected in order to characterise surface ocean particles across the oceanographic gradients that characterise the Southern Ocean. these data were generated by IMAS Honour student Veda Surapaneni, and were included in her honours thesis.

The CANYONS voyage on RV Investigator aimed to investigate past and present processes governing the flow pathways, formation and geochemical signatures of Antarctic Bottom Water (AABW) off Cape Darnley, East Antarctica. The proposed survey area was focussed on the Wild and Daly canyons and the adjacent sediment drifts - the Daly and ‘Armand’ drifts. The survey aimed to collect systematic multibeam bathymetry and sub-bottom profiles across the region to support collection of long sediment cores (up to 24 m), Kasten cores and multicores, CTDs (conductivity- temperature-depth instruments) and deep towed camera transects. This dataset reports analyses of particulate organic carbon and biogenic silica from two CTD casts conducted in the Cape Darnley region. The voyage was terminated after a medical evacuation so only two CTD stations were occupied. These data were generated by IMAS Honour student Veda Surapaneni, and were included in her honours thesis. The dataset also includes hydrochemistry, DIC, Alkalinity and pigment data generated by CSIRO, although these data are published in other national repositories and reproduced here for completeness and convenience only.

The downward transport of organic particles produced by marine organisms is a key control on the ocean's carbon storage. Measurements of particle attenuation through the water column have historically been used to infer the sequestration potential of the biological carbon pump. While often modelled using a single power-law fit, this simplification may obscure important depth-dependent processes. Using data from biogeochemical-Argo floats in the Southern Ocean, here we show that splitting the water column into two distinct regimes captures depth-dependent variability in particle attenuation more effectively. Compared to the single power-law fit the model reveals greater attenuation just below the productive layer, reducing particulate organic carbon flux into the mesopelagic (200 - 400 m) by 40 - 60 %. Our findings suggest a more mechanistic representation of particle attenuation is needed to improve estimates of carbon transport and the durability of biologically-based marine carbon dioxide removal technologies, and to reduce uncertainties in ocean-climate feedbacks and future climate projections.