scholarly journals Short-Term Dynamics of North Sea Bacterioplankton-Dissolved Organic Matter Coherence on Molecular Level

2016 ◽  
Vol 7 ◽  
Author(s):  
Judith Lucas ◽  
Irina Koester ◽  
Antje Wichels ◽  
Jutta Niggemann ◽  
Thorsten Dittmar ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
North Sea ◽  
Molecular Level ◽  
Short Term

scholarly journals Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation

2018 ◽  
Vol 15 (21) ◽  
pp. 6637-6648 ◽  
Author(s):  
Yinghui Wang ◽  
Robert G. M. Spencer ◽  
David C. Podgorski ◽  
Anne M. Kellerman ◽  
Harunur Rashid ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Molecular Level ◽  
Tibet Plateau ◽  
Permafrost Degradation ◽  
Hydrological Conditions ◽  
14C Age ◽  
Alpine Stream ◽  
Qinghai Tibet Plateau

Abstract. The Qinghai–Tibet Plateau (QTP) accounts for approximately 70 % of global alpine permafrost and is an area sensitive to climate change. The thawing and mobilization of ice-rich and organic-carbon-rich permafrost impact hydrologic conditions and biogeochemical processes on the QTP. Despite numerous studies of Arctic permafrost, there are no reports to date for the molecular-level in-stream processing of permafrost-derived dissolved organic matter (DOM) on the QTP. In this study, we examine temporal and spatial changes of DOM along an alpine stream (3850–3207 m above sea level) by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), accelerator mass spectrometry (AMS) and UV–visible spectroscopy. Compared to downstream sites, dissolved organic matter (DOM) at the headstream site exhibited older radiocarbon age, higher mean molecular weight, higher aromaticity and fewer highly unsaturated compounds. At the molecular level, 6409 and 1345 formulas were identified as unique to the active layer (AL) leachate and permafrost layer (PL) leachate, respectively. Comparing permafrost leachates to the downstream site, 59 % of AL-specific formulas and 90 % of PL-specific formulas were degraded, likely a result of rapid in-stream degradation of permafrost-derived DOM. From peak discharge in the summer to low flow in late autumn, the DOC concentration at the headstream site decreased from 13.9 to 10.2 mg L−1, while the 14C age increased from 745 to 1560 years before present (BP), reflecting an increase in the relative contribution of deep permafrost carbon due to the effect of changing hydrological conditions over the course of the summer on the DOM source (AL vs. PL). Our study thus demonstrates that hydrological conditions impact the mobilization of permafrost carbon in an alpine fluvial network, the signature of which is quickly lost through in-stream mineralization and transformation.

The Role of Dissolved Organic Matter Composition in Determining Photochemical Reactivity at the Molecular Level

2019 ◽  
Vol 53 (20) ◽  
pp. 11725-11734 ◽  
Author(s):  
Stephanie M. Berg ◽  
Quinn T. Whiting ◽  
Joseph A. Herrli ◽  
Ronan Winkels ◽  
Kristine H. Wammer ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Molecular Level ◽  
Photochemical Reactivity ◽  
Organic Matter Composition

scholarly journals Short-Term Effects of Fertilization on Dissolved Organic Matter in Soil Leachate

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1617 ◽  
Author(s):  
Alexandra Tiefenbacher ◽  
Gabriele Weigelhofer ◽  
Andreas Klik ◽  
Matthias Pucher ◽  
Jakob Santner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Sandy Loam ◽  
Organic Fertilizer ◽  
Molecular Size ◽  
Pig Slurry ◽  
Silt Loam ◽  
Short Term ◽  
Soil Leachate ◽  
Calcium Ammonium Nitrate

Besides the importance of dissolved organic matter (DOM) in soil biogeochemical processes, there is still a debate on how agricultural intensification affects the leaching of terrestrial DOM into adjacent aquatic ecosystems. In order to close this linkage, we conducted a short-term (45 day) lysimeter experiment with silt loam and sandy loam undisturbed/intact soil cores. Mineral (calcium ammonium nitrate) or organic (pig slurry) fertilizer was applied on the soil surface with a concentration equivalent to 130 kg N ha−1. On average, amounts of leached DOC over 45 days ranged between 20.4 mg (silt loam, mineral fertilizer) and 34.4 mg (sandy loam, organic fertilizer). Both, mineral and organic fertilization of a silt loam reduced concentration of dissolved organic carbon (DOC) in the leachate and shifted its composition towards a microbial-like signature (BIX) with a higher aromaticity (Fi) and a lower molecular size (E2:E3). However, in sandy loam only mineral fertilization affected organic matter leaching. There, lowered DOC concentrations with a smaller molecular size (E2:E3) could be detected. The overall effect of fertilization on DOC leaching and DOM composition was interrelated with soil texture and limited to first 12 days. Our results highlight the need for management measures, which prevent or reduce fast flow paths leading soil water directly into aquatic systems, such as surface flow, fast subsurface flow, or drainage water.

scholarly journals Spatiotemporal transformation of dissolved organic matter along an alpine stream flowpath on the Qinghai-Tibetan Plateau: importance of source and permafrost degradation

2018 ◽  
Author(s):  
Yinghui Wang ◽  
Robert G. M. Spencer ◽  
David Podgorski ◽  
Anne Kellerman ◽  
Harunur Rashid ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Tibetan Plateau ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Molecular Level ◽  
Permafrost Degradation ◽  
Hydrological Conditions ◽  
14C Age ◽  
Alpine Stream

Abstract. The Qinghai-Tibetan Plateau (QTP) accounts for approximately 70 % of global alpine permafrost and is an area sensitive to climate change. The thawing and mobilization of ice and organic carbon-rich permafrost impact hydrologic conditions and biogeochemical processes on the QTP. Despite numerous studies of Arctic permafrost, there are no reports to date for the molecular-level in-stream processing of permafrost-derived dissolved organic matter (DOM) on the QTP. In this study, we examine temporal and spatial changes of chemical composition of DOM and 14C age of dissolved organic carbon (DOC) along an alpine stream (3850–3207 m above sea level) by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), accelerator mass spectrometry (AMS) and UV-visible spectroscopy. Compared to downstream sites, the DOM at the headstream exhibited older radiocarbon (14C-DOC) age, higher mean molecular weight, higher aromaticity and fewer polyunsaturated components. At the molecular level, 6409 and 1345 formulas were identified as unique to the active layer (AL) leachate and permafrost layer (PL) leachate, respectively. Comparing permafrost leachates to the downstream site, 59 % of AL-specific formulas and 90 % of PL-specific formulas were degraded, likely a result of rapid instream degradation of permafrost-derived DOM. From peak discharge in the summer to low flow in late autumn, the DOC concentration at the headstream site decreased from 13.9 to 10.2 mg/L, while the 14C-DOC age increased from 745 to 1560 years before present (BP), reflecting an increase in relative contribution of deep permafrost carbon due to the effect of changing hydrological conditions over the course of the summer on DOM source (AL vs. PL). Our study thus demonstrates that hydrological conditions impact the mobilization of permafrost carbon in an alpine fluvial network, the signature of which is quickly lost through in-stream metabolism.

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