Coastal versus open-ocean denitrification in the Arabian Sea
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 p...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2006-01-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/3/621/2006/bg-3-621-2006.pdf |
| _version_ | 1819232354632204288 |
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| author | S. W. A. Naqvi H. Naik A. Pratihary W. D'Souza W. D'Souza P. V. Narvekar D. A. Jayakumar D. A. Jayakumar A. H. Devol T. Yoshinari T. Saino |
| author_facet | S. W. A. Naqvi H. Naik A. Pratihary W. D'Souza W. D'Souza P. V. Narvekar D. A. Jayakumar D. A. Jayakumar A. H. Devol T. Yoshinari T. Saino |
| author_sort | S. W. A. Naqvi |
| collection | DOAJ |
| 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 enhanced nutrient loading from land. The two systems also differ from each other with regard to the modes of nitrous oxide (N<sub>2</sub>O) production: In the open-ocean suboxic zone, an accumulation of secondary nitrite (NO<sub>2</sub><sup>−</sup>) is invariably accompanied by depletion of N<sub>2</sub>O whereas in the coastal suboxic zone high NO<sub>2</sub><sup>−</sup> and very high N<sub>2</sub>O concentrations frequently co-occur, indicating, respectively, net consumption and net production of N<sub>2</sub>O by denitrifiers. The extents of heavier isotope enrichment in the combined nitrate and nitrite (NO<sub>3</sub><sup>−</sup>+NO<sub>2</sub><sup>−</sup>) pool and in N<sub>2</sub>O in reducing waters appear to be considerably smaller in the coastal region, reflecting more varied sources/sinks and/or different isotopic fractionation factors. |
| first_indexed | 2024-12-23T11:59:32Z |
| format | Article |
| id | doaj.art-ce2b919cc7654dde91dfa88705fca10d |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-23T11:59:32Z |
| publishDate | 2006-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-ce2b919cc7654dde91dfa88705fca10d2022-12-21T17:48:00ZengCopernicus PublicationsBiogeosciences1726-41701726-41892006-01-0134621633Coastal versus open-ocean denitrification in the Arabian SeaS. W. A. NaqviH. NaikA. PratiharyW. D'SouzaW. D'SouzaP. V. NarvekarD. A. JayakumarD. A. JayakumarA. H. DevolT. YoshinariT. SainoThe 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<sub>2</sub>O) production: In the open-ocean suboxic zone, an accumulation of secondary nitrite (NO<sub>2</sub><sup>−</sup>) is invariably accompanied by depletion of N<sub>2</sub>O whereas in the coastal suboxic zone high NO<sub>2</sub><sup>−</sup> and very high N<sub>2</sub>O concentrations frequently co-occur, indicating, respectively, net consumption and net production of N<sub>2</sub>O by denitrifiers. The extents of heavier isotope enrichment in the combined nitrate and nitrite (NO<sub>3</sub><sup>−</sup>+NO<sub>2</sub><sup>−</sup>) pool and in N<sub>2</sub>O in reducing waters appear to be considerably smaller in the coastal region, reflecting more varied sources/sinks and/or different isotopic fractionation factors.http://www.biogeosciences.net/3/621/2006/bg-3-621-2006.pdf |
| spellingShingle | S. W. A. Naqvi H. Naik A. Pratihary W. D'Souza W. D'Souza P. V. Narvekar D. A. Jayakumar D. A. Jayakumar A. H. Devol T. Yoshinari T. Saino Coastal versus open-ocean denitrification in the Arabian Sea Biogeosciences |
| title | Coastal versus open-ocean denitrification in the Arabian Sea |
| title_full | Coastal versus open-ocean denitrification in the Arabian Sea |
| title_fullStr | Coastal versus open-ocean denitrification in the Arabian Sea |
| title_full_unstemmed | Coastal versus open-ocean denitrification in the Arabian Sea |
| title_short | Coastal versus open-ocean denitrification in the Arabian Sea |
| title_sort | coastal versus open ocean denitrification in the arabian sea |
| url | http://www.biogeosciences.net/3/621/2006/bg-3-621-2006.pdf |
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