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Author(s): Mark A. Altabet (corresponding author) [1]; Matthew J. Higginson [1]; David W. Murray [2] Most global biogeochemical processes are known to respond to climate change, some of which have [...]

Nitrogen-isotope preserved in Southern Ocean sediments, together with geochemical tracers for settling biogenic matter fluxes, reveals patterns of earlier nutrient supply to to phytoplankton in the region. The reduction of the CO2 leak from ocean to atmosphere through higher surface-water stratification at the Polar Front, contributed more to decreased CO2 concentrations than increased export of organic carbon to deep waters from the surface, during the last glacial period.

A study of nitrogen isotopes at three sites in the Arabian Sea indicates changes in the 15N/14N values due to climatic variations, as confirmed by the agreement of the variations with Milankovitch cycle values. This implies that subsurface nitrate level and denitrification vary with climate. These factors may have serious implications on the changes in marine biogeochemical cycles.

Vertical nitrate transport in the North Atlantic, North Pacific and the Indian oceans were observed in Rhizosolenia mats to study the mechanism of nutrient transfer in abundant diatom mats. The study indicated that mats rising to the surface were richer in internal nitrates than those mats which were sinking to the ocean floor. These reuslts indicate that Rhizosolenia mats can provide as mush as 50% of nitrohen requirements of surface water.

Examines the effect of millennial-scale changes in Arabian Sea denitrification on atmospheric carbon dioxide. Importance of marine denitrification in the regulation of atmospheric greenhouse gases; Variation of denitrification with glacial-interglacial cycles; Response of global marine productivity to changes in denitrification.

Examines the effect of millennial-scale changes in Arabian Sea denitrification on atmospheric carbon dioxide. Importance of marine denitrification in the regulation of atmospheric greenhouse gases; Variation of denitrification with glacial-interglacial cycles; Response of global marine productivity to changes in denitrification.