Abstract
We present depth profiles of Cd isotopes and concentrations from the Southern Ocean at four stations in the Atlantic sector along the Greenwich Meridian (47 degree S to 68 degree S) located across the main Antarctic frontal zones and productivity belt. The vertical profiles of Cd concentration typically show low values in surface waters, elevated values at intermediate depths, reflecting remineralization of sinking particulate organic matter, and constant values in deep waters. The surface-to-deep isotopic gradient shows "heavy" Cd isotope signatures in the mixed surface layer, becoming more pronounced northward, with values up to epsilon 112/110Cd of around +4.1 in the Subantarctic sector of the Southern Ocean. Deep Antarctic waters display a uniform and "light" epsilon 112/110Cd of +1.18 plus or minus 0.38 and Cd concentrations of 0.761 plus or minus 0.101 nmol/kg (n = 23, 2SD). Intermediate waters are characterized by epsilon 112/110Cd lying between those of surface and deep waters, with a constant value of about +0.8 in the High Nutrient Low Chlorophyll sector and a notably higher value of +2.3 in the Subantarctic sector.