| dc.description.abstract | Surface sediments from the western continental shelf of India were analysed for total organic carbon (TOC), total nitrogen (TN), total hydrolysable carbohydrates (TCHO) and proteins (PRT) during the late summer monsoon (September-October, 2003) and pre-monsoon (March-April, 2004) seasons. The region experienced entirely different hydrographic characteristics and productivity patterns during the two seasons. Low oxygenated, cold, nutrient rich (DO < 180 mu M, SST < 28 degrees C, NO sub(3) less than 2 mu M) surface waters and the existence of subsurface suboxia were the hydrographic features during late summer due to the persistence of upwelling. Meanwhile, during pre-monsoon the region was oligotrophic and oxygen saturated (DO >200 mu M, NO sub(3) <2 mu M). Satellite imagery, in situ Chl a and zooplankton biomass showed high production along the region during late summer compared to pre-monsoon. Sedimentary organic matter (SOM) was of marine origin during both seasons, as indicated by the C/N ratios. TCHO + PRT: TOC and PRT: TCHO revealed aged organic matter and did not change between the seasons. During late summer, TOC and the reactive organic matter (TCHO and PRT) in the surface sediments were concentrated along the regions (13–17 degrees N) where active upwelling was observed, suggesting a close coupling between SOM characteristics and the surface ocean productivity | |
