Erik Jeppesen

TY - JOUR

T1 - Autochthonous dissolved organic matter potentially fuels methane ebullition from experimental lakes

AU - Zhou, Yongqiang

AU - Zhou, Lei

AU - Zhang, Yunlin

AU - Garcia de Souza, Javier

AU - Podgorski, David C.

AU - Spencer, Robert G.M.

AU - Jeppesen, Erik

AU - Davidson, Thomas A.

N1 - Copyright © 2019 Elsevier Ltd. All rights reserved.

PY - 2019/12

Y1 - 2019/12

N2 - Shallow lakes are hotspots for carbon processing and important natural sources of methane (CH4) emission. Ebullitive CH4 flux may constitute the overwhelming majority of total CH4 flux, but the episodic nature of ebullition events makes determining both quantity and the controlling factors challenging. Here we used the world's longest running shallow-lake mesocosm facility, where the experimental treatments are low and high nutrients crossed with three temperatures, to investigate the quantity and drivers of CH4 ebullition. The mean CH4 ebullition flux in the high nutrient treatment (41.5 ± 52.3 mg CH4–C m−2 d−1) mesocosms was significantly larger than in the low nutrient treatment (3.6 ± 5.4 mg CH4–C m−2 d−1) mesocosms, varying with temperature scenarios. Over eight weeks from June to August covered here warming resulted in a weak, but insignificant enhancement of CH4 ebullition. We found significant positive relationships between ebullition and chlorophyll-a, dissolved organic carbon (DOC), biodegradable DOC, δ2H, δ18O and δ13C-DOC, autochthonous dissolved organic matter (DOM) fluorescent components, and a fraction of lipids, proteins, and lignins revealed using ultrahigh-resolution mass spectrometry, and a negative relationship between ebullitive CH4 flux and the percentage volume inhabited of macrophytes. A 24 h laboratory bio-incubation experiment performed at room temperature (20 ± 2 °C) in the dark further revealed a rapid depletion of algal-DOM concurrent with a massive increased CH4 production, whereas soil-derived DOM had a limited effect on CH4 production. We conclude that eutrophication likely induced the loss of macrophytes and increase in algal biomass, and the resultant accumulation algal derived bio-labile DOM potentially drives enhanced outgassing of ebullitive CH4 from the shallow-lake mesocosms.

AB - Shallow lakes are hotspots for carbon processing and important natural sources of methane (CH4) emission. Ebullitive CH4 flux may constitute the overwhelming majority of total CH4 flux, but the episodic nature of ebullition events makes determining both quantity and the controlling factors challenging. Here we used the world's longest running shallow-lake mesocosm facility, where the experimental treatments are low and high nutrients crossed with three temperatures, to investigate the quantity and drivers of CH4 ebullition. The mean CH4 ebullition flux in the high nutrient treatment (41.5 ± 52.3 mg CH4–C m−2 d−1) mesocosms was significantly larger than in the low nutrient treatment (3.6 ± 5.4 mg CH4–C m−2 d−1) mesocosms, varying with temperature scenarios. Over eight weeks from June to August covered here warming resulted in a weak, but insignificant enhancement of CH4 ebullition. We found significant positive relationships between ebullition and chlorophyll-a, dissolved organic carbon (DOC), biodegradable DOC, δ2H, δ18O and δ13C-DOC, autochthonous dissolved organic matter (DOM) fluorescent components, and a fraction of lipids, proteins, and lignins revealed using ultrahigh-resolution mass spectrometry, and a negative relationship between ebullitive CH4 flux and the percentage volume inhabited of macrophytes. A 24 h laboratory bio-incubation experiment performed at room temperature (20 ± 2 °C) in the dark further revealed a rapid depletion of algal-DOM concurrent with a massive increased CH4 production, whereas soil-derived DOM had a limited effect on CH4 production. We conclude that eutrophication likely induced the loss of macrophytes and increase in algal biomass, and the resultant accumulation algal derived bio-labile DOM potentially drives enhanced outgassing of ebullitive CH4 from the shallow-lake mesocosms.

KW - Bio-labile

KW - Chromophoric dissolved organic matter (CDOM)

KW - Greenhouse gases

KW - Methane (CH) ebullition

KW - Parallel factor analysis (PARAFAC)

KW - Ultrahigh resolution mass spectrometry

KW - Methane (CH4) ebullition

KW - GREENHOUSE-GAS EMISSIONS

KW - FLUORESCENCE SPECTROSCOPY

KW - CARBON

KW - ENVIRONMENTS

KW - QUALITY

KW - PERSISTENCE

KW - MASS-SPECTROMETRY

KW - SHALLOW EUTROPHIC LAKE

KW - TAIHU

KW - ANCIENT

U2 - 10.1016/j.watres.2019.115048

DO - 10.1016/j.watres.2019.115048

M3 - Journal article

C2 - 31518733

AN - SCOPUS:85071875316

VL - 166

JO - Water Research

JF - Water Research

SN - 0043-1354

M1 - 115048

ER -