Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis

Southeast Asian peatlands supply ∼10 % of the global flux of dissolved organic carbon (DOC) from land to the ocean, but the biogeochemical cycling of this peat-derived DOC in coastal environments is still poorly understood. Here, we use fluorescence spectroscopy and parallel factor (PARAFAC) analysi...

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Main Authors: Zhou, Yongli, Martin, Patrick, Müller, Moritz
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2019
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Online Access:https://hdl.handle.net/10356/83523
http://hdl.handle.net/10220/49763
https://doi.org/10.21979/N9/RCYCIT
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spelling sg-ntu-dr.10356-835232023-02-28T16:41:56Z Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis Zhou, Yongli Martin, Patrick Müller, Moritz Asian School of the Environment Fluorescence Spectroscopy Science::Geology DOM Pool Southeast Asian peatlands supply ∼10 % of the global flux of dissolved organic carbon (DOC) from land to the ocean, but the biogeochemical cycling of this peat-derived DOC in coastal environments is still poorly understood. Here, we use fluorescence spectroscopy and parallel factor (PARAFAC) analysis to distinguish different fractions of dissolved organic matter (DOM) in peat-draining rivers, estuaries and coastal waters of Sarawak, Borneo. The terrigenous fractions showed high concentrations at freshwater stations within the rivers, and conservative mixing with seawater across the estuaries. The autochthonous DOM fraction, in contrast, showed low concentrations throughout our study area at all salinities. The DOM pool was also characterized by a high degree of humification in all rivers and estuaries up to salinities of 25. These results indicate a predominantly terrestrial origin of the riverine DOM pool. Only at salinities > 25 did we observe an increase in the proportion of autochthonous relative to terrestrial DOM. Natural sunlight exposure experiments with river water and seawater showed high photolability of the terrigenous DOM fractions, suggesting that photodegradation may account for the observed changes in the DOM composition in coastal waters. Nevertheless, based on our fluorescence data, we estimate that at least 20 %–25 % of the DOC at even our most marine stations (salinity > 31) was terrestrial in origin, indicating that peatlands likely play an important role in the carbon biogeochemistry of Southeast Asian shelf seas. MOE (Min. of Education, S’pore) Published version 2019-08-23T05:06:31Z 2019-12-06T15:24:48Z 2019-08-23T05:06:31Z 2019-12-06T15:24:48Z 2019 Journal Article Zhou, Y., Martin, P., & Müller, M. (2019). Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis. Biogeosciences, 16(13), 2733-2749. doi:10.5194/bg-16-2733-2019 1726-4170 https://hdl.handle.net/10356/83523 http://hdl.handle.net/10220/49763 10.5194/bg-16-2733-2019 en Biogeosciences https://doi.org/10.21979/N9/RCYCIT © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License. 17 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Fluorescence Spectroscopy
Science::Geology
DOM Pool
spellingShingle Fluorescence Spectroscopy
Science::Geology
DOM Pool
Zhou, Yongli
Martin, Patrick
Müller, Moritz
Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis
description Southeast Asian peatlands supply ∼10 % of the global flux of dissolved organic carbon (DOC) from land to the ocean, but the biogeochemical cycling of this peat-derived DOC in coastal environments is still poorly understood. Here, we use fluorescence spectroscopy and parallel factor (PARAFAC) analysis to distinguish different fractions of dissolved organic matter (DOM) in peat-draining rivers, estuaries and coastal waters of Sarawak, Borneo. The terrigenous fractions showed high concentrations at freshwater stations within the rivers, and conservative mixing with seawater across the estuaries. The autochthonous DOM fraction, in contrast, showed low concentrations throughout our study area at all salinities. The DOM pool was also characterized by a high degree of humification in all rivers and estuaries up to salinities of 25. These results indicate a predominantly terrestrial origin of the riverine DOM pool. Only at salinities > 25 did we observe an increase in the proportion of autochthonous relative to terrestrial DOM. Natural sunlight exposure experiments with river water and seawater showed high photolability of the terrigenous DOM fractions, suggesting that photodegradation may account for the observed changes in the DOM composition in coastal waters. Nevertheless, based on our fluorescence data, we estimate that at least 20 %–25 % of the DOC at even our most marine stations (salinity > 31) was terrestrial in origin, indicating that peatlands likely play an important role in the carbon biogeochemistry of Southeast Asian shelf seas.
author2 Asian School of the Environment
author_facet Asian School of the Environment
Zhou, Yongli
Martin, Patrick
Müller, Moritz
format Article
author Zhou, Yongli
Martin, Patrick
Müller, Moritz
author_sort Zhou, Yongli
title Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis
title_short Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis
title_full Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis
title_fullStr Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis
title_full_unstemmed Composition and cycling of dissolved organic matter from tropical peatlands of coastal Sarawak, Borneo, revealed by fluorescence spectroscopy and parallel factor analysis
title_sort composition and cycling of dissolved organic matter from tropical peatlands of coastal sarawak, borneo, revealed by fluorescence spectroscopy and parallel factor analysis
publishDate 2019
url https://hdl.handle.net/10356/83523
http://hdl.handle.net/10220/49763
https://doi.org/10.21979/N9/RCYCIT
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