Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden

Dissolved organic matter (DOM) is the major absorber of sunlight in most natural waters and a critical component of the carbon cycle in aquatic systems. The photochemical decomposition of DOM can have a significant impact on the landscape-atmosphere carbon exchange. However, little is known about ho...

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Main Author: Younes, Hani
Format: Other/Unknown Material
Language:English
Published: Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap 2020
Subjects:
DOM
Online Access:http://lup.lub.lu.se/student-papers/record/9017941
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spelling ftulundlupsp:oai:lup-student-papers.lub.lu.se:9017941 2023-11-12T03:59:14+01:00 Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden Younes, Hani 2020 application/pdf http://lup.lub.lu.se/student-papers/record/9017941 eng eng Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap http://lup.lub.lu.se/student-papers/record/9017941 Photo-reactivity DOM subarctic lakes EEM-PARAFAC. Brownification Earth and Environmental Sciences H2 2020 ftulundlupsp 2023-10-25T22:29:16Z Dissolved organic matter (DOM) is the major absorber of sunlight in most natural waters and a critical component of the carbon cycle in aquatic systems. The photochemical decomposition of DOM can have a significant impact on the landscape-atmosphere carbon exchange. However, little is known about how changing characteristics of DOM due to water browning (allochthonous inputs of DOM from terrestrial sources) affect the photochemical processing of the DOM. A shift from in situ self-produced (autochthonous) DOM to allochthonous DOM in clear tundra lakes may imply changes in the optical characteristics and thus photo-reactivity of the DOM. In this study, I measured the absorption of ultraviolet (UV) light and subsequent CO2 emissions resulting from the photochemical DOM decay in 148 subarctic lakes from northern Sweden exposed to artificial sunlight, to assess how increasing chromophoric dissolved organic matter CDOM (browning) may affect the photo mineralization processes. In parallel the chemical composition of the DOM was assessed using fluorescence excitation-emission matrix analysis. The study lakes are situated along an environmental gradient in the subarctic Abisko region, ranging from brown-water lakes connected with some small mires to tundra clear-water lakes. The main objective of this study was to see how increasing CDOM due to increasing terrestrial inputs to the lakes affects the photochemical DOM mineralization. As expected the photo decay rates were positively correlated to the CDOM in absolute values. However, the photo decay per unit of absorbed light energy did not increase with increasing CDOM, but rather showed a weak decreasing trend (R2 = 0.07), which indicates that browning may lead to less photochemically induced CO2 emissions from lakes at any given level of UV light energy absorption. The percentage of lost dissolved organic carbon through photo-mineralization was significantly negatively correlated to the CDOM as well. Fluorescence analyses helped explain these patterns, as humic-like ... Other/Unknown Material Abisko Northern Sweden Subarctic Tundra Lund University Publications Student Papers (LUP-SP) Abisko ENVELOPE(18.829,18.829,68.349,68.349) Browning ENVELOPE(164.050,164.050,-74.617,-74.617)
institution Open Polar
collection Lund University Publications Student Papers (LUP-SP)
op_collection_id ftulundlupsp
language English
topic Photo-reactivity
DOM
subarctic lakes
EEM-PARAFAC. Brownification
Earth and Environmental Sciences
spellingShingle Photo-reactivity
DOM
subarctic lakes
EEM-PARAFAC. Brownification
Earth and Environmental Sciences
Younes, Hani
Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden
topic_facet Photo-reactivity
DOM
subarctic lakes
EEM-PARAFAC. Brownification
Earth and Environmental Sciences
description Dissolved organic matter (DOM) is the major absorber of sunlight in most natural waters and a critical component of the carbon cycle in aquatic systems. The photochemical decomposition of DOM can have a significant impact on the landscape-atmosphere carbon exchange. However, little is known about how changing characteristics of DOM due to water browning (allochthonous inputs of DOM from terrestrial sources) affect the photochemical processing of the DOM. A shift from in situ self-produced (autochthonous) DOM to allochthonous DOM in clear tundra lakes may imply changes in the optical characteristics and thus photo-reactivity of the DOM. In this study, I measured the absorption of ultraviolet (UV) light and subsequent CO2 emissions resulting from the photochemical DOM decay in 148 subarctic lakes from northern Sweden exposed to artificial sunlight, to assess how increasing chromophoric dissolved organic matter CDOM (browning) may affect the photo mineralization processes. In parallel the chemical composition of the DOM was assessed using fluorescence excitation-emission matrix analysis. The study lakes are situated along an environmental gradient in the subarctic Abisko region, ranging from brown-water lakes connected with some small mires to tundra clear-water lakes. The main objective of this study was to see how increasing CDOM due to increasing terrestrial inputs to the lakes affects the photochemical DOM mineralization. As expected the photo decay rates were positively correlated to the CDOM in absolute values. However, the photo decay per unit of absorbed light energy did not increase with increasing CDOM, but rather showed a weak decreasing trend (R2 = 0.07), which indicates that browning may lead to less photochemically induced CO2 emissions from lakes at any given level of UV light energy absorption. The percentage of lost dissolved organic carbon through photo-mineralization was significantly negatively correlated to the CDOM as well. Fluorescence analyses helped explain these patterns, as humic-like ...
format Other/Unknown Material
author Younes, Hani
author_facet Younes, Hani
author_sort Younes, Hani
title Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden
title_short Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden
title_full Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden
title_fullStr Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden
title_full_unstemmed Photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern Sweden
title_sort photo-chemical reactivity of dissolved organic carbon in subarctic lakes from northern sweden
publisher Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap
publishDate 2020
url http://lup.lub.lu.se/student-papers/record/9017941
long_lat ENVELOPE(18.829,18.829,68.349,68.349)
ENVELOPE(164.050,164.050,-74.617,-74.617)
geographic Abisko
Browning
geographic_facet Abisko
Browning
genre Abisko
Northern Sweden
Subarctic
Tundra
genre_facet Abisko
Northern Sweden
Subarctic
Tundra
op_relation http://lup.lub.lu.se/student-papers/record/9017941
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