DOM degradation by light and microbes along the Yukon River-coastal ocean continuum

Abstract The Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic war...

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Autores principales:	Brice K. Grunert, Maria Tzortziou, Patrick Neale, Alana Menendez, Peter Hernes
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/b8f12ff9367a4649888a9a9747508add
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spelling	oai:doaj.org-article:b8f12ff9367a4649888a9a9747508add2021-12-02T15:43:17ZDOM degradation by light and microbes along the Yukon River-coastal ocean continuum10.1038/s41598-021-89327-92045-2322https://doaj.org/article/b8f12ff9367a4649888a9a9747508add2021-05-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-89327-9https://doaj.org/toc/2045-2322Abstract The Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.Brice K. GrunertMaria TzortziouPatrick NealeAlana MenendezPeter HernesNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-14 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Brice K. Grunert Maria Tzortziou Patrick Neale Alana Menendez Peter Hernes DOM degradation by light and microbes along the Yukon River-coastal ocean continuum
description	Abstract The Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.
format	article
author	Brice K. Grunert Maria Tzortziou Patrick Neale Alana Menendez Peter Hernes
author_facet	Brice K. Grunert Maria Tzortziou Patrick Neale Alana Menendez Peter Hernes
author_sort	Brice K. Grunert
title	DOM degradation by light and microbes along the Yukon River-coastal ocean continuum
title_short	DOM degradation by light and microbes along the Yukon River-coastal ocean continuum
title_full	DOM degradation by light and microbes along the Yukon River-coastal ocean continuum
title_fullStr	DOM degradation by light and microbes along the Yukon River-coastal ocean continuum
title_full_unstemmed	DOM degradation by light and microbes along the Yukon River-coastal ocean continuum
title_sort	dom degradation by light and microbes along the yukon river-coastal ocean continuum
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/b8f12ff9367a4649888a9a9747508add
work_keys_str_mv	AT bricekgrunert domdegradationbylightandmicrobesalongtheyukonrivercoastaloceancontinuum AT mariatzortziou domdegradationbylightandmicrobesalongtheyukonrivercoastaloceancontinuum AT patrickneale domdegradationbylightandmicrobesalongtheyukonrivercoastaloceancontinuum AT alanamenendez domdegradationbylightandmicrobesalongtheyukonrivercoastaloceancontinuum AT peterhernes domdegradationbylightandmicrobesalongtheyukonrivercoastaloceancontinuum
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DOM degradation by light and microbes along the Yukon River-coastal ocean continuum

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