Nutrient depletion and particulate matter near the iceedge in the Weddell Sea

Abstract

The region between Elephant Island and the South Orkney Islands (53.5 S, 46.5 W) was occupied by Winter Weddell Sea water and a thck layer of summer and surface modified Weddell Water. High correlations between nutrients (nitrate, total inorganic carbon, silicate) and oxygen with salinity were found in the upper 150 m near the ice-edge. Nutrient depletion was calculated and cor- related with the melting ice processes. When 1 m of ice melts, the average amount of total carbonate and nutrients removed is equivalent to a production of 33 g C m-' yr-'. Increases of oxygen were detected with high rates of nutrient and carbon depletion. However, significant oxygen losses in the melting water body were estimated from the conservative 'NO' parameter. The amount of nutrients removed during pack-ice melting was about 3 times higher than that taken up in the water column. Analyses of particulate material in the ice samples showed similar C:N ratios to those estimated by the decrease of nutrients in the water column.