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Maren Walter

and 11 more

The Aurora vent field (82°53.83’ N, 6°15.32’ W) is located in the weakly stratified Arctic Ocean under perennial ice cover at the western edge of the ultraslow-spreading Gakkel Ridge, the slowest spreading mid-ocean ridge on Earth. Here, we report data on the dispersal of the proximal hydrothermal plume in this extreme environment. The hydrothermal plume is of unusual dimensions, with a small horizontal, but large vertical extent, which is caused by the hydrography of the Arctic Ocean. Water column parameters such as turbidity and redox potential show a highly variable but horizontally confined non-buoyant plume. Dissolved iron (dFe), manganese (dMn), δ3He, and methane (CH4) all show distinct enrichments in the hydrothermal plume relative to background deep-water, but relatively low peak concentrations due to the dilution over a vertical extent of over 500 m. Plume particle samples exhibit elevated Fe/Al ratios consistent with Fe-oxyhydroxide precipitation close to the vent, whereas particulate Mn/Al ratios do not reveal any complementary pMn enrichments in the proximal plume. Positive correlation between Fe/Al, and several other element/Al ratios (e.g. P, V, As) are consistent with scavenging of these elements onto Fe-hydroxide plume particles and removal into the underlying sediments. Surface sediment samples collected close to Aurora reveal highly elevated concentrations of hydrothermally-sourced elements in the immediate vicinity of the vent-site. For example, proximal surface sediments contained up to 8222 mg kg-1 Cu, whereas Cu concentrations in core tops a few kilometers away from the site were much lower (<50 mg kg-1).