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Coastal versus open-ocean denitrification in the Arabian Sea

IR@NIO: CSIR-National Institute Of Oceanography, Goa


Field	Value

Creator	Naqvi, S.W.A. Naik, H. Pratihary, A.K. DeSouza, W. Narvekar, P.V. Jayakumar, D.A. Devol, A.H. Yoshinari, T. Saino, T.

Date	2007-03-07T08:50:25Z 2007-03-07T08:50:25Z 2006

Identifier	Biogeosciences, vol.3(3), 621-633p. http://drs.nio.org/drs/handle/2264/542

Description	The Arabian Sea contains one of the three major open-ocean denitrification zones in the world. In addition, pelagic denitrification also occurs over the inner and mid-shelf off the west coast of India. The major differences between the two environments are highlighted using the available data. The perennial open-ocean system occupies two orders of magnitude larger volume than the seasonal coastal system, however, the latter offers more extreme conditions (greater nitrate consumption leading to complete anoxia). Unlike the open-ocean system, the coastal system seems to have undergone a change (i.e., it has intensified) over the past few decades presumably due to gone enhanced nutrient loading from land. The two systems also differ from each other with regard to the modes of nitrous oxide (N2O) production: in the open-ocean suboxic zone, an accumulation of secondary nitrite (NO2-) is invariably accompanied by oxic depletion of N2O whereas in the coastal suboxic zone high NO2- and very high N2O concentrations frequently co-occur, indicating, respectively, net consumption and net production of N2O by denitrifiers. The extents of heavier isotope enrichment in the combined nitrate and nitrite (NO3 sup(-)+ NO2-) pool and in N2O in reducing waters appear to be considerably smaller in the coastal region, reflecting more varied sources/sinks and/or different isotopic fractionation factors.

Format	1296028 bytes application/pdf

Language	en

Publisher	The European Geosciences Union

Title	Coastal versus open-ocean denitrification in the Arabian Sea

Type	Article