Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum
Chromophoric dissolved organic matter (CDOM) is the dominant absorber of ultraviolet radiation in the ocean, but its sources within the ocean, as well as its chemical composition, remain uncertain. One source of marine CDOM is Sargassum, an epipelagic marine macro brown alga common to the Gulf of Me...
Published in: | Frontiers in Marine Science |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Frontiers
2020
|
Subjects: | |
Online Access: | https://oceanrep.geomar.de/id/eprint/51278/ https://oceanrep.geomar.de/id/eprint/51278/1/fmars-07-588287.pdf https://oceanrep.geomar.de/id/eprint/51278/2/Data_Sheet_1_Optical%20Properties%20and%20Photochemical%20Transformation%20of%20the%20Dissolved%20Organic%20Matter%20Released%20by%20Sargassum.docx https://doi.org/10.3389/fmars.2020.588287 |
id |
ftoceanrep:oai:oceanrep.geomar.de:51278 |
---|---|
record_format |
openpolar |
spelling |
ftoceanrep:oai:oceanrep.geomar.de:51278 2023-05-15T17:35:08+02:00 Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum Powers, Leanne C. Del Vecchio, Rossana Blough, Neil V. McDonald, Natasha Schmitt-Kopplin, Philippe Gonsior, Michael 2020-11-12 text https://oceanrep.geomar.de/id/eprint/51278/ https://oceanrep.geomar.de/id/eprint/51278/1/fmars-07-588287.pdf https://oceanrep.geomar.de/id/eprint/51278/2/Data_Sheet_1_Optical%20Properties%20and%20Photochemical%20Transformation%20of%20the%20Dissolved%20Organic%20Matter%20Released%20by%20Sargassum.docx https://doi.org/10.3389/fmars.2020.588287 en eng Frontiers https://oceanrep.geomar.de/id/eprint/51278/1/fmars-07-588287.pdf https://oceanrep.geomar.de/id/eprint/51278/2/Data_Sheet_1_Optical%20Properties%20and%20Photochemical%20Transformation%20of%20the%20Dissolved%20Organic%20Matter%20Released%20by%20Sargassum.docx Powers, L. C., Del Vecchio, R., Blough, N. V., McDonald, N., Schmitt-Kopplin, P. and Gonsior, M. (2020) Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum. Open Access Frontiers in Marine Science, 7 . Art.Nr. 588287. DOI 10.3389/fmars.2020.588287 <https://doi.org/10.3389/fmars.2020.588287>. doi:10.3389/fmars.2020.588287 cc_by_4.0 info:eu-repo/semantics/openAccess Article PeerReviewed 2020 ftoceanrep https://doi.org/10.3389/fmars.2020.588287 2023-04-07T15:53:19Z Chromophoric dissolved organic matter (CDOM) is the dominant absorber of ultraviolet radiation in the ocean, but its sources within the ocean, as well as its chemical composition, remain uncertain. One source of marine CDOM is Sargassum, an epipelagic marine macro brown alga common to the Gulf of Mexico, Caribbean, and Western North Atlantic. Furthermore, Sargassum contains phlorotannins, a class of polyphenols that may have similar optical properties to terrestrial polyphenols. Here, we analyze Sargassum CDOM optical properties, acquired from absorption and fluorescence spectra of filtered samples collected during Sargassum exudation experiments in seawater tanks. To further evaluate the structural basis of Sargassum CDOM optical properties, Sargassum CDOM was collected by solid phase extraction (SPE) and its chemical composition was tested by pH titration and sodium borohydride reduction. These chemical tests revealed that Sargassum CDOM absorption spectra respond similarly to pH titration and borohydride reduction when compared to terrestrially-derived materials, but Sargassum CDOM has unique absorbance peaks in difference spectra that have not been observed in terrestrially-derived CDOM. These absorbance features are consistent with the deprotonation of modified Sargassum phlorotannins, which are likely highly related phenolic acids and polyphenols. Sargassum CDOM was also more rapidly photodegraded when compared to terrestrial CDOM such as Suwannee River Natural Organic Matter. Similar to terrestrial DOM, ultrahigh resolution mass spectrometry revealed that sunlight decreases relative abundances of m/z ions and molecular formulas with an average O/C ratio of 0.6 and an average H/C ratio of 0.9, suggesting preferential photodegradation and/or phototransformation of hydrogen-deficient and oxygenated compounds, such as Sargassum phlorotannins. Assuming a large fraction of Sargassum CDOM is quickly mineralized to CO2 during its rapid photodegradation, Sargassum could play a major role in marine photochemical ... Article in Journal/Newspaper North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Suwannee River ENVELOPE(-100.046,-100.046,56.125,56.125) Frontiers in Marine Science 7 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Chromophoric dissolved organic matter (CDOM) is the dominant absorber of ultraviolet radiation in the ocean, but its sources within the ocean, as well as its chemical composition, remain uncertain. One source of marine CDOM is Sargassum, an epipelagic marine macro brown alga common to the Gulf of Mexico, Caribbean, and Western North Atlantic. Furthermore, Sargassum contains phlorotannins, a class of polyphenols that may have similar optical properties to terrestrial polyphenols. Here, we analyze Sargassum CDOM optical properties, acquired from absorption and fluorescence spectra of filtered samples collected during Sargassum exudation experiments in seawater tanks. To further evaluate the structural basis of Sargassum CDOM optical properties, Sargassum CDOM was collected by solid phase extraction (SPE) and its chemical composition was tested by pH titration and sodium borohydride reduction. These chemical tests revealed that Sargassum CDOM absorption spectra respond similarly to pH titration and borohydride reduction when compared to terrestrially-derived materials, but Sargassum CDOM has unique absorbance peaks in difference spectra that have not been observed in terrestrially-derived CDOM. These absorbance features are consistent with the deprotonation of modified Sargassum phlorotannins, which are likely highly related phenolic acids and polyphenols. Sargassum CDOM was also more rapidly photodegraded when compared to terrestrial CDOM such as Suwannee River Natural Organic Matter. Similar to terrestrial DOM, ultrahigh resolution mass spectrometry revealed that sunlight decreases relative abundances of m/z ions and molecular formulas with an average O/C ratio of 0.6 and an average H/C ratio of 0.9, suggesting preferential photodegradation and/or phototransformation of hydrogen-deficient and oxygenated compounds, such as Sargassum phlorotannins. Assuming a large fraction of Sargassum CDOM is quickly mineralized to CO2 during its rapid photodegradation, Sargassum could play a major role in marine photochemical ... |
format |
Article in Journal/Newspaper |
author |
Powers, Leanne C. Del Vecchio, Rossana Blough, Neil V. McDonald, Natasha Schmitt-Kopplin, Philippe Gonsior, Michael |
spellingShingle |
Powers, Leanne C. Del Vecchio, Rossana Blough, Neil V. McDonald, Natasha Schmitt-Kopplin, Philippe Gonsior, Michael Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum |
author_facet |
Powers, Leanne C. Del Vecchio, Rossana Blough, Neil V. McDonald, Natasha Schmitt-Kopplin, Philippe Gonsior, Michael |
author_sort |
Powers, Leanne C. |
title |
Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum |
title_short |
Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum |
title_full |
Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum |
title_fullStr |
Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum |
title_full_unstemmed |
Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum |
title_sort |
optical properties and photochemical transformation of the dissolved organic matter released by sargassum |
publisher |
Frontiers |
publishDate |
2020 |
url |
https://oceanrep.geomar.de/id/eprint/51278/ https://oceanrep.geomar.de/id/eprint/51278/1/fmars-07-588287.pdf https://oceanrep.geomar.de/id/eprint/51278/2/Data_Sheet_1_Optical%20Properties%20and%20Photochemical%20Transformation%20of%20the%20Dissolved%20Organic%20Matter%20Released%20by%20Sargassum.docx https://doi.org/10.3389/fmars.2020.588287 |
long_lat |
ENVELOPE(-100.046,-100.046,56.125,56.125) |
geographic |
Suwannee River |
geographic_facet |
Suwannee River |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://oceanrep.geomar.de/id/eprint/51278/1/fmars-07-588287.pdf https://oceanrep.geomar.de/id/eprint/51278/2/Data_Sheet_1_Optical%20Properties%20and%20Photochemical%20Transformation%20of%20the%20Dissolved%20Organic%20Matter%20Released%20by%20Sargassum.docx Powers, L. C., Del Vecchio, R., Blough, N. V., McDonald, N., Schmitt-Kopplin, P. and Gonsior, M. (2020) Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum. Open Access Frontiers in Marine Science, 7 . Art.Nr. 588287. DOI 10.3389/fmars.2020.588287 <https://doi.org/10.3389/fmars.2020.588287>. doi:10.3389/fmars.2020.588287 |
op_rights |
cc_by_4.0 info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.3389/fmars.2020.588287 |
container_title |
Frontiers in Marine Science |
container_volume |
7 |
_version_ |
1766134182413598720 |