| Popis: |
We present particulate barium data collected using sequencing sediment traps in the Ross Sea region of the Southern Ocean. Data were collected in 1991–92, 1994–95, and 1996–98 from two separate field programs. Samples were collected at ∼200 m depth and ∼75 m above the seafloor (450–765 m depth). Ba fluxes in the shallow traps at all sites are uniformly low and the barium to organic carbon (Ba:Corg) ratios in these traps typically agree within a factor of two both spatially and temporally. Deeper trap fluxes are as much as an order of magnitude larger than shallow trap fluxes. In addition, the Ba:Corg ratio in the deeper traps varies by more than an order of magnitude, with the ratio decreasing with increasing rates of organic carbon flux. Increases in the deeper trap fluxes may result from horizontal transport of material from other regions of the Ross Sea, resuspension of previously deposited sediment, and increases in biogenic Ba formation with depth. Data presented here and within the contemporary literature lead us to speculate that much of the biogenic Ba may be formed in the water column at depths greater than 200 m. Also the factor of 10 range in the Ba:Corg ratio in combination with the depth dependence of biogenic barium formation leads us to conclude that biogenic barium formation may depend on the rate at which particles sink. Independent of the causal mechanism, the variations in this ratio imply that using an algorithm that relates barium export to carbon export may be imprudent in regions of highly variable carbon flux. |
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