Accumulation of Terrestrial Dissolved Organic Matter Potentially Enhances Dissolved Methane Levels in Eutrophic Lake Taihu, China

Inland waters play an important role for the storage of chromophoric dissolved organic matter (CDOM) and outgassing of methane (CH4). However, to date, linkages between the optical dynamics of CDOM and dissolved CH4 levels remain largely unknown. We used multi-year (2012−2014) seasonal data series c...

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Bibliographic Details
Published in:Environmental science & technology 2018-09, Vol.52 (18), p.10297-10306
Main Authors: Zhou, Yongqiang, Xiao, Qitao, Yao, Xiaolong, Zhang, Yunlin, Zhang, Mi, Shi, Kun, Lee, Xuhui, Podgorski, David C, Qin, Boqiang, Spencer, Robert G. M, Jeppesen, Erik
Format: Article
Language:English
Subjects:
Aromaticity
Chemical compounds
Chemical oxygen demand
Dissolved organic carbon
Dissolved organic matter
Dissolved oxygen
Eutrophic environments
Eutrophic lakes
Eutrophication
Fluorescence
Fluorophores
Inland waters
Lakes
Mass spectrometry
Mass spectroscopy
Methane
Organic chemicals
Organic chemistry
Outgassing
Rivers
Terrestrial environments
Ultraviolet radiation
Underwater
Water analysis
Water pollution
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Summary:Inland waters play an important role for the storage of chromophoric dissolved organic matter (CDOM) and outgassing of methane (CH4). However, to date, linkages between the optical dynamics of CDOM and dissolved CH4 levels remain largely unknown. We used multi-year (2012−2014) seasonal data series collected from Lake Taihu and 51 connecting channels to investigate how CDOM optical dynamics may impact dissolved CH4 levels in the lake. High dissolved CH4 in the northwestern inflowing river mouths coincided with high underwater UV–vis light availability, dissolved organic carbon (DOC), chemical oxygen demand (COD), DOM aromaticity, terrestrial humic-rich fluorescence, in situ measured terrestrial CDOM, depleted dissolved oxygen (DO), stable isotopic δ2H, and δ18O compared with other lake regions. Our results further revealed positive relationships between dissolved CH4 and CDOM absorption at 350 nm, i.e. a(350), COD, DOC, terrestrial humic-rich fluorophores, and DOM aromaticity, and negative relationships between dissolved CH4 and DO, δ2H, and δ18O. The central lake samples showed a major contribution of terrestrial-sourced molecular formulas to the ultrahigh resolution mass spectrometry data, suggesting the presence of allochthonous DOM sources even here. We conclude that an elevated terrestrial CDOM input likely enhances dissolved CH4 levels in Lake Taihu.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.8b02163