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Coastal versus open-ocean denitrification in the Arabian Sea.
- Source :
- Biogeosciences Discussions; 2006, Vol. 3 Issue 3, p665-695, 31p
- Publication Year :
- 2006
-
Abstract
- 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 enhanced nutrient loading from land. The two systems also differ from each other with regard to the modes of nitrous oxide (N<subscript>2</subscript>O) production: in the open-ocean suboxic zone, an accumulation of secondary nitrite (NO<subscript>2</subscript><superscript>-</superscript>) is invariably accompanied by depletion of N<subscript>2</subscript>O whereas in the coastal suboxic zone high NO<subscript>2</subscript><superscript>-</superscript> and very high N<subscript>2</subscript>O concentrations frequently co-occur, indicating, respectively, net consumption and net production of N<subscript>2</subscript>O by denitrifiers. The extents of heavier isotope enrichment in the combined nitrate and nitrite (NO<subscript>3</subscript><superscript>-</superscript>+NO<subscript>2</subscript><superscript>-</superscript>) pool and in N<subscript>2</subscript>O in reducing waters appear to be considerably smaller in the coastal region, reflecting more varied sources/sinks and/or different isotopic fractionation factors. [ABSTRACT FROM AUTHOR]
- Subjects :
- DENITRIFICATION
NITROUS oxide
CHEMICAL reduction
Subjects
Details
- Language :
- English
- ISSN :
- 18106277
- Volume :
- 3
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Biogeosciences Discussions
- Publication Type :
- Academic Journal
- Accession number :
- 21417274
- Full Text :
- https://doi.org/10.5194/bgd-3-665-2006