Disequilibria betweenRa, Pb and Po in the Arctic Ocean and the implications for chemical modification of the Pacific water inflow |
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| Authors: | RM Moore JN Smith |
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| Abstract: | Measurements have been made of226Ra and both dissolved and particulate forms of210Pb and210Po in a vertical profile at 85°50′N, 108°50′W in the Arctic Ocean.In the upper water column226Ra shows a concentration maximum that is coincident with one in the nutrients, silicate, phosphate, and nitrate, while at the same depth, dissolved and particulate210Pb and210Po all show minimum concentrations. It is suggested that the concentration maxima are partly due to sources of the respective elements in the continental shelf sediments, the shelf waters being subsequently advected into the Arctic Ocean basins. The210Pb and210Po minima have similarly been explained by interaction between the shelf sediments and overlying waters. An estimate is made of the possible contributions of shelf sediments to the layer of silica-rich water which covers the Canada Basin at a depth of 100–150 m.Residence times have been calculated for dissolved210Pb and210Po at various depths in the water column. Surface water residence times of dissolved and particulate forms of these radionuclides are longer than in surface Atlantic waters, probably due to lower biological activity in the surface waters of the Canada Basin. An estimatee has been made of the average sinking velocity of particulate material. |
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