Barium as a productivity proxy in continental margin sediments: a study from the eastern Arabian Sea

Barium, aluminum, cadmium and uranium were analyzed in 112 surface sediment samples from the western continental margin of India. Excess Ba (Baxs) concentrations are high at the SW margin of India, an area of high productivity and lower at the central western continental margin, an area of lower productivity. High organic carbon export coupled with high sedimentation rates and a relatively oxygenated sediment sea water interface appear to result in the accumulation of high concentrations of Baxs at the SW Indian margin. At the NW Indian margin, where the productivity is moderate to high, suboxic diagenesis is in accord with relatively low Baxs values and high concentrations of Cd and U, two elements accumulating under oxygen-deficient and/or sulfidic conditions. Our results indicate that although Ba tends to be partially lost during suboxic diagenesis, the productivity trend along the western continental margin of India still appears to be reflected by this element.