Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences
The Ross Sea, one of the most productive regions in the Southern Ocean, plays a significant role in deep water formation and carbon cycling. Dissolved organic carbon (DOC) concentrations and chromophoric dissolved organic matter (CDOM) absorption and fluorescence (FDOM) properties were studied in co...
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ftlouisianastuir:oai:digitalcommons.lsu.edu:oceanography_coastal_pubs-1185 2023-06-11T04:06:06+02:00 Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences D'Sa, Eurico J. Kim, Hyun-Cheol Ha, Sun-Yong Joshi, Ishan 2021-10-27T07:00:00Z https://digitalcommons.lsu.edu/oceanography_coastal_pubs/185 https://doi.org/10.3389/fmars.2021.749096 unknown LSU Digital Commons https://digitalcommons.lsu.edu/oceanography_coastal_pubs/185 doi:10.3389/fmars.2021.749096 Faculty Publications text 2021 ftlouisianastuir https://doi.org/10.3389/fmars.2021.749096 2023-05-28T18:45:24Z The Ross Sea, one of the most productive regions in the Southern Ocean, plays a significant role in deep water formation and carbon cycling. Dissolved organic carbon (DOC) concentrations and chromophoric dissolved organic matter (CDOM) absorption and fluorescence (FDOM) properties were studied in conjunction with biophysical properties during austral summer. Elevated values of both DOC (mean 47.82 ± 5.70 μM) and CDOM (absorption coefficient at 325 nm, acdom325: mean 0.31 ± 0.18 m–1) observed in the upper shelf waters in the southwest (SW), north of the Ross Ice Shelf (RIS), the northwest and along a transect inward of the shelf break, suggested in situ production and accumulation linked to the productive spring/summer season. However, regional differences were observed in CDOM with acdom325 higher (0.63 ± 0.19 m–1) and its spectral slope S275–295 lower (24.06 ± 2.93 μm–1) in the SW compared to other regions (0.25 ± 0.08 m–1 and 28.92 ± 2.67 μm–1, respectively). Similarly, the specific UV absorption coefficient or SUVA254 determined at 254 nm was greater (1.85 ± 0.55 m2 mg–1 C) compared to other regions (1.07 ± 0.24 m2 mg–1 C), indicating CDOM of greater molecular weight and aromaticity in the SW. Phytoplankton absorption spectra indicated the shallow mixed layer of SW Ross Sea to be dominated by diatoms (e.g., Fragilariopsis spp.), a preferential food source for grazers such as the Antarctic krill, which in large numbers have been shown to enhance CDOM absorption, a likely source in the SW. Excitation-emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) retrieved one protein-like and two humic-like FDOM fractions commonly observed in the global ocean. In contrast to acdom325 which was uncorrelated to DOC, we observed weak but significant positive correlations between the humic-like FDOM with salinity and DOC, high value of the biological index parameter BIX and an instance of increasing FDOM with depth at a location with sinking organic matter, suggesting autochthonous production ... Text Antarc* Antarctic Antarctic Krill Ice Shelf Ross Ice Shelf Ross Sea Southern Ocean LSU Digital Commons (Louisiana State University) Antarctic Austral Ross Ice Shelf Ross Sea Southern Ocean The Antarctic Frontiers in Marine Science 8 |
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LSU Digital Commons (Louisiana State University) |
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The Ross Sea, one of the most productive regions in the Southern Ocean, plays a significant role in deep water formation and carbon cycling. Dissolved organic carbon (DOC) concentrations and chromophoric dissolved organic matter (CDOM) absorption and fluorescence (FDOM) properties were studied in conjunction with biophysical properties during austral summer. Elevated values of both DOC (mean 47.82 ± 5.70 μM) and CDOM (absorption coefficient at 325 nm, acdom325: mean 0.31 ± 0.18 m–1) observed in the upper shelf waters in the southwest (SW), north of the Ross Ice Shelf (RIS), the northwest and along a transect inward of the shelf break, suggested in situ production and accumulation linked to the productive spring/summer season. However, regional differences were observed in CDOM with acdom325 higher (0.63 ± 0.19 m–1) and its spectral slope S275–295 lower (24.06 ± 2.93 μm–1) in the SW compared to other regions (0.25 ± 0.08 m–1 and 28.92 ± 2.67 μm–1, respectively). Similarly, the specific UV absorption coefficient or SUVA254 determined at 254 nm was greater (1.85 ± 0.55 m2 mg–1 C) compared to other regions (1.07 ± 0.24 m2 mg–1 C), indicating CDOM of greater molecular weight and aromaticity in the SW. Phytoplankton absorption spectra indicated the shallow mixed layer of SW Ross Sea to be dominated by diatoms (e.g., Fragilariopsis spp.), a preferential food source for grazers such as the Antarctic krill, which in large numbers have been shown to enhance CDOM absorption, a likely source in the SW. Excitation-emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) retrieved one protein-like and two humic-like FDOM fractions commonly observed in the global ocean. In contrast to acdom325 which was uncorrelated to DOC, we observed weak but significant positive correlations between the humic-like FDOM with salinity and DOC, high value of the biological index parameter BIX and an instance of increasing FDOM with depth at a location with sinking organic matter, suggesting autochthonous production ... |
format |
Text |
author |
D'Sa, Eurico J. Kim, Hyun-Cheol Ha, Sun-Yong Joshi, Ishan |
spellingShingle |
D'Sa, Eurico J. Kim, Hyun-Cheol Ha, Sun-Yong Joshi, Ishan Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences |
author_facet |
D'Sa, Eurico J. Kim, Hyun-Cheol Ha, Sun-Yong Joshi, Ishan |
author_sort |
D'Sa, Eurico J. |
title |
Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences |
title_short |
Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences |
title_full |
Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences |
title_fullStr |
Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences |
title_full_unstemmed |
Ross Sea Dissolved Organic Matter Optical Properties During an Austral Summer: Biophysical Influences |
title_sort |
ross sea dissolved organic matter optical properties during an austral summer: biophysical influences |
publisher |
LSU Digital Commons |
publishDate |
2021 |
url |
https://digitalcommons.lsu.edu/oceanography_coastal_pubs/185 https://doi.org/10.3389/fmars.2021.749096 |
geographic |
Antarctic Austral Ross Ice Shelf Ross Sea Southern Ocean The Antarctic |
geographic_facet |
Antarctic Austral Ross Ice Shelf Ross Sea Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctic Krill Ice Shelf Ross Ice Shelf Ross Sea Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Krill Ice Shelf Ross Ice Shelf Ross Sea Southern Ocean |
op_source |
Faculty Publications |
op_relation |
https://digitalcommons.lsu.edu/oceanography_coastal_pubs/185 doi:10.3389/fmars.2021.749096 |
op_doi |
https://doi.org/10.3389/fmars.2021.749096 |
container_title |
Frontiers in Marine Science |
container_volume |
8 |
_version_ |
1768377873875337216 |