Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic
Photolysis of dimethylsulfide (DMS), a secondary photochemical process mediated by chromophoric dissolved organic matter (CDOM), has previously been demonstrated to be an important loss term of DMS in the surface layer of warm seas and the Southern Ocean. The role of photolysis in regulating the DMS...
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ftdoajarticles:oai:doaj.org/article:fbb7f35c43dc443e98fbaeb2d6584701 2023-05-15T15:02:00+02:00 Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic A. Taalba H. Xie M. G. Scarratt S. Bélanger M. Levasseur 2013-11-01T00:00:00Z https://doi.org/10.5194/bg-10-6793-2013 https://doaj.org/article/fbb7f35c43dc443e98fbaeb2d6584701 EN eng Copernicus Publications http://www.biogeosciences.net/10/6793/2013/bg-10-6793-2013.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-10-6793-2013 https://doaj.org/article/fbb7f35c43dc443e98fbaeb2d6584701 Biogeosciences, Vol 10, Iss 11, Pp 6793-6806 (2013) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2013 ftdoajarticles https://doi.org/10.5194/bg-10-6793-2013 2022-12-31T14:32:58Z Photolysis of dimethylsulfide (DMS), a secondary photochemical process mediated by chromophoric dissolved organic matter (CDOM), has previously been demonstrated to be an important loss term of DMS in the surface layer of warm seas and the Southern Ocean. The role of photolysis in regulating the DMS dynamics in northern polar seas remains, however, less clear. This study for the first time determined the apparent quantum yield (AQY) spectra of DMS photooxidation in Canadian Arctic seas covering Baffin Bay, the Mackenzie estuary and shelf, and the Canada Basin. The DMS AQY was fairly invariant at salinities < 25 but rose rapidly with further increasing salinity in an exponential manner. Salinity can therefore be used as a quantitative indicator of the DMS AQY. The DMS AQY in the ultraviolet (UV) wavelengths was linearly and positively correlated with the spectral slope coefficient (275–295 nm) of the CDOM absorption spectrum, suggesting that marine CDOM photosensitizes the degradation of DMS more efficiently than does terrestrial CDOM or that coastal waters contain higher concentrations of substrates (most likely dissolved organic matter and redox metals) that compete for DMS-oxidizing radical intermediates. High concentrations of nitrate (~ 12 μmol L −1 ) in deep water samples boosted DMS photooxidation by 70–80%, due likely to radical chemistry of nitrate photolysis. Coupled optical-photochemical modeling, based on the obtained DMS AQY spectra, shows that UV-A (320–400 nm) accounted for 60–75% of the DMS photolysis in the sunlit surface layer and that photochemistry degraded DMS on an e -folding time from 9 to 100 d (mean: 29 d). The photooxidation term on average accounted for 21% of the DMS gross loss rate and was comparable to the atmospheric DMS ventilation rate estimated for the same geographic regions. The methodology adopted here to study the relationship between CDOM quality/origin and DMS AQYs, if applicable to other ocean areas, may bring results of global significance for DMS cycling and might ... Article in Journal/Newspaper Arctic Baffin Bay Baffin Bay Baffin canada basin Southern Ocean Directory of Open Access Journals: DOAJ Articles Arctic Southern Ocean Baffin Bay Canada Biogeosciences 10 11 6793 6806 |
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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 A. Taalba H. Xie M. G. Scarratt S. Bélanger M. Levasseur Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Photolysis of dimethylsulfide (DMS), a secondary photochemical process mediated by chromophoric dissolved organic matter (CDOM), has previously been demonstrated to be an important loss term of DMS in the surface layer of warm seas and the Southern Ocean. The role of photolysis in regulating the DMS dynamics in northern polar seas remains, however, less clear. This study for the first time determined the apparent quantum yield (AQY) spectra of DMS photooxidation in Canadian Arctic seas covering Baffin Bay, the Mackenzie estuary and shelf, and the Canada Basin. The DMS AQY was fairly invariant at salinities < 25 but rose rapidly with further increasing salinity in an exponential manner. Salinity can therefore be used as a quantitative indicator of the DMS AQY. The DMS AQY in the ultraviolet (UV) wavelengths was linearly and positively correlated with the spectral slope coefficient (275–295 nm) of the CDOM absorption spectrum, suggesting that marine CDOM photosensitizes the degradation of DMS more efficiently than does terrestrial CDOM or that coastal waters contain higher concentrations of substrates (most likely dissolved organic matter and redox metals) that compete for DMS-oxidizing radical intermediates. High concentrations of nitrate (~ 12 μmol L −1 ) in deep water samples boosted DMS photooxidation by 70–80%, due likely to radical chemistry of nitrate photolysis. Coupled optical-photochemical modeling, based on the obtained DMS AQY spectra, shows that UV-A (320–400 nm) accounted for 60–75% of the DMS photolysis in the sunlit surface layer and that photochemistry degraded DMS on an e -folding time from 9 to 100 d (mean: 29 d). The photooxidation term on average accounted for 21% of the DMS gross loss rate and was comparable to the atmospheric DMS ventilation rate estimated for the same geographic regions. The methodology adopted here to study the relationship between CDOM quality/origin and DMS AQYs, if applicable to other ocean areas, may bring results of global significance for DMS cycling and might ... |
format |
Article in Journal/Newspaper |
author |
A. Taalba H. Xie M. G. Scarratt S. Bélanger M. Levasseur |
author_facet |
A. Taalba H. Xie M. G. Scarratt S. Bélanger M. Levasseur |
author_sort |
A. Taalba |
title |
Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic |
title_short |
Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic |
title_full |
Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic |
title_fullStr |
Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic |
title_full_unstemmed |
Photooxidation of dimethylsulfide (DMS) in the Canadian Arctic |
title_sort |
photooxidation of dimethylsulfide (dms) in the canadian arctic |
publisher |
Copernicus Publications |
publishDate |
2013 |
url |
https://doi.org/10.5194/bg-10-6793-2013 https://doaj.org/article/fbb7f35c43dc443e98fbaeb2d6584701 |
geographic |
Arctic Southern Ocean Baffin Bay Canada |
geographic_facet |
Arctic Southern Ocean Baffin Bay Canada |
genre |
Arctic Baffin Bay Baffin Bay Baffin canada basin Southern Ocean |
genre_facet |
Arctic Baffin Bay Baffin Bay Baffin canada basin Southern Ocean |
op_source |
Biogeosciences, Vol 10, Iss 11, Pp 6793-6806 (2013) |
op_relation |
http://www.biogeosciences.net/10/6793/2013/bg-10-6793-2013.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-10-6793-2013 https://doaj.org/article/fbb7f35c43dc443e98fbaeb2d6584701 |
op_doi |
https://doi.org/10.5194/bg-10-6793-2013 |
container_title |
Biogeosciences |
container_volume |
10 |
container_issue |
11 |
container_start_page |
6793 |
op_container_end_page |
6806 |
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1766333999190376448 |