Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications
Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammoni...
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2012
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Online Access: | https://doi.org/10.5194/bg-9-3047-2012 https://doaj.org/article/130316266b5e4b6097af3d804a84d73a |
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ftdoajarticles:oai:doaj.org/article:130316266b5e4b6097af3d804a84d73a 2023-05-15T15:40:24+02:00 Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications H. Xie S. Bélanger G. Song R. Benner A. Taalba M. Blais J.-É. Tremblay M. Babin 2012-08-01T00:00:00Z https://doi.org/10.5194/bg-9-3047-2012 https://doaj.org/article/130316266b5e4b6097af3d804a84d73a EN eng Copernicus Publications http://www.biogeosciences.net/9/3047/2012/bg-9-3047-2012.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-9-3047-2012 1726-4170 1726-4189 https://doaj.org/article/130316266b5e4b6097af3d804a84d73a Biogeosciences, Vol 9, Iss 8, Pp 3047-3061 (2012) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2012 ftdoajarticles https://doi.org/10.5194/bg-9-3047-2012 2022-12-31T01:00:02Z Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH 4 + ). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH 4 + photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen:carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO 2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO 2 : CO : NH 4 + molar ratio of 165 : 11 : 1 in the estuary, 60 : 3 : 1 on the shelf, and 18 : 2 : 1 in the Canada Basin. The NH 4 + efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l −1 d −1 on the Mackenzie Shelf and 3.7 nmol l −1 d −1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m −2 d −1 and 11.3 μmol m −2 d −1 . The offshore depth-integrated rate in August (8.0 μmol m −2 d −1 ) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH 4 + photoproduction in the entire study area was estimated to be 1.4 × 10 8 moles, with 85% of it being generated in summer when ... Article in Journal/Newspaper Beaufort Sea canada basin Mackenzie river Mackenzie Shelf Sea ice Directory of Open Access Journals: DOAJ Articles Mackenzie River Canada Biogeosciences 9 8 3047 3061 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 H. Xie S. Bélanger G. Song R. Benner A. Taalba M. Blais J.-É. Tremblay M. Babin Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH 4 + ). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH 4 + photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen:carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO 2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO 2 : CO : NH 4 + molar ratio of 165 : 11 : 1 in the estuary, 60 : 3 : 1 on the shelf, and 18 : 2 : 1 in the Canada Basin. The NH 4 + efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l −1 d −1 on the Mackenzie Shelf and 3.7 nmol l −1 d −1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m −2 d −1 and 11.3 μmol m −2 d −1 . The offshore depth-integrated rate in August (8.0 μmol m −2 d −1 ) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH 4 + photoproduction in the entire study area was estimated to be 1.4 × 10 8 moles, with 85% of it being generated in summer when ... |
format |
Article in Journal/Newspaper |
author |
H. Xie S. Bélanger G. Song R. Benner A. Taalba M. Blais J.-É. Tremblay M. Babin |
author_facet |
H. Xie S. Bélanger G. Song R. Benner A. Taalba M. Blais J.-É. Tremblay M. Babin |
author_sort |
H. Xie |
title |
Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications |
title_short |
Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications |
title_full |
Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications |
title_fullStr |
Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications |
title_full_unstemmed |
Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications |
title_sort |
photoproduction of ammonium in the southeastern beaufort sea and its biogeochemical implications |
publisher |
Copernicus Publications |
publishDate |
2012 |
url |
https://doi.org/10.5194/bg-9-3047-2012 https://doaj.org/article/130316266b5e4b6097af3d804a84d73a |
geographic |
Mackenzie River Canada |
geographic_facet |
Mackenzie River Canada |
genre |
Beaufort Sea canada basin Mackenzie river Mackenzie Shelf Sea ice |
genre_facet |
Beaufort Sea canada basin Mackenzie river Mackenzie Shelf Sea ice |
op_source |
Biogeosciences, Vol 9, Iss 8, Pp 3047-3061 (2012) |
op_relation |
http://www.biogeosciences.net/9/3047/2012/bg-9-3047-2012.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-9-3047-2012 1726-4170 1726-4189 https://doaj.org/article/130316266b5e4b6097af3d804a84d73a |
op_doi |
https://doi.org/10.5194/bg-9-3047-2012 |
container_title |
Biogeosciences |
container_volume |
9 |
container_issue |
8 |
container_start_page |
3047 |
op_container_end_page |
3061 |
_version_ |
1766372659536330752 |