| Summary: | The spatial distribution, biogeochemical cycling andexternal sources of dissolved iron and dissolvedmanganese (DFe and DMn) were investigated inRyder Bay, a small coastal embayment of the WestAntarctic Peninsula, during Austral summer (2013and 2014). Dissolved concentrations were measuredthroughout the water column at 11 stations withinRyder Bay. The concentration ranges of DFe andDMn were large, between 0.58 and 32.7 nM, andbetween 0.18 and 26.2 nM, respectively, exhibitingstrong gradients from the surface to the bottom.Surface concentrations of DFe and DMn werehigher than concentrations reported for the SouthernOcean and coastal Antarctic waters, and extremelyhigh concentrations were detected in deep water.Glacial meltwater and shallow sediments are likelyto be the main sources of DFe and DMn in theeuphotic zone, while lateral advection associatedwith local sediment resuspension and verticalmixing are significant sources for intermediateand deep waters. During summer, vertical mixingof intermediate and deep waters and sedimentresuspension occurring from Marguerite Trough toRyder Bay are thought to be amplified by a seriesof overflows at the sills, enhancing the input ofFe and Mn from bottom sediment and increasingtheir concentrations up to the euphotic layer.
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