scholarly journals Characteristics and sources of dissolved organic matter in a glacier in the northern Tibetan Plateau: differences between different snow categories

2018 ◽  
Vol 59 (77) ◽  
pp. 31-40 ◽  
Author(s):  
Lin Feng ◽  
Yanqing An ◽  
Jianzhong Xu ◽  
Shichang Kang
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Dissolved Organic Matter ◽  
Melting Rate ◽  
Ion Cyclotron Resonance ◽  
The Tibetan Plateau ◽  
Mountain Glaciers ◽  
Northern Tibetan Plateau ◽  
Fresh Snow ◽  
Northern Edge

AbstractDissolved organic matter (DOM) in mountain glaciers is an important source of carbon for downstream aquatic systems, and its impact is expected to increase due to the increased melting rate of glaciers. We present a comprehensive study of Laohugou glacier no. 12 (LHG) at the northern edge of the Tibetan Plateau to characterize the DOM composition and sources by analyzing surface fresh snow, granular ice samples, and snow pit samples which covered a whole year cycle of 2014/15. Excitation–emission matrix fluorescence spectroscopy analysis of the DOM with parallel factor analysis (EEM-PARAFAC) identified four components, including a microbially humic-like component (C1), two protein-like components (C2 and C3) and a terrestrial humic-like component (C4). The use of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) showed that DOM from all these samples was dominated by CHO and CHON molecular formulas, mainly corresponding to lipids and aliphatic/proteins compounds, reflecting the presence of significant amounts of microbially derived and/or deposited biogenic DOM. The molecular compositions of DOM showed more CHON compounds in granular ice than in fresh snow, likely suggesting newly formed DOM from microbes during snowmelting.

scholarly journals Physical and chemical evolution of dissolved organic matter across the ablation season on a glacier in the central Tibetan Plateau

2017 ◽  
Author(s):  
Lin Feng ◽  
Yanqing An ◽  
Jianzhong Xu ◽  
Shichang Kang ◽  
Xiaofei Li ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Dissolved Organic Matter ◽  
Ion Cyclotron Resonance ◽  
Dynamic Variations ◽  
Central Tibetan Plateau ◽  
Surface Snow ◽  
Fresh Snow ◽  
Physical And Chemical

Abstract. The physical evolution (metamorphism) of snow is known to affect the chemical composition of dissolved organic matter (DOM) within it. Here, we present a comprehensive study on the Dongkemadi glacier in the central Tibetan Plateau by analyzing surface snow/ice samples collected from May to October 2015. Based on their physical descriptions, these samples were grouped into four categories, i.e., fresh snow, fine firn, coarse firn, and granular ice that represented the different stages of snowmelt. The concentrations of dissolved organic carbon (DOC) decreased from fresh snow (26.8 μmol L−1) to fine firn (15.0 μmol L−1) and then increased from fine firn to coarse firn (26.1 μmol L−1) and granular ice (34.4 μmol L−1). This reflected the dynamic variations in DOC observed during snowmelt. The use of excitation emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC) identified three protein-like components (C1, C2 and C4) and one microbial humic-like component (C3), which reflected the presence of significant amounts of microbially derived DOM in surface snow/ice. The molecular level compositions of DOM identified using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) also showed the presence of molecules that were newly produced during snowmelt. These results suggest that snowmelt not only induced a loss of DOM but also intensified the in situ microbial activities that enriched and modified it. These findings are important for understanding the evolution of the physical and chemical characteristics of DOM during the ablation season and can also shed some light on the nature of biogeochemical cycles in cryospheric regions.

Source and biolability of ancient dissolved organic matter in glacier and lake ecosystems on the Tibetan Plateau

2014 ◽  
Vol 142 ◽  
pp. 64-74 ◽  
Author(s):  
Robert G.M. Spencer ◽  
Weidong Guo ◽  
Peter A. Raymond ◽  
Thorsten Dittmar ◽  
Eran Hood ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Dissolved Organic Matter ◽  
The Tibetan Plateau ◽  
Lake Ecosystems

Microbial production and consumption of dissolved organic matter in glacial ecosystems on the Tibetan Plateau

2019 ◽  
Vol 160 ◽  
pp. 18-28 ◽  
Author(s):  
Lei Zhou ◽  
Yongqiang Zhou ◽  
Yang Hu ◽  
Jian Cai ◽  
Xin Liu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Dissolved Organic Matter ◽  
Microbial Production ◽  
The Tibetan Plateau ◽  
Production And Consumption

scholarly journals Impact of Chromophoric dissolved organic matter on light absorption in lake water on the Tibetan Plateau, China

2017 ◽  
Author(s):  
Ciren Nima ◽  
Børge Hamre ◽  
Øyvind Frette ◽  
Svein Rune Erga ◽  
Yi-Chun Chen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Dissolved Organic Matter ◽  
Lake Water ◽  
Light Absorption ◽  
Chromophoric Dissolved Organic Matter ◽  
The Tibetan Plateau

scholarly journals Surface ozone at Nam Co (4730 m a.s.l.) in the inland Tibetan Plateau: variation, synthesis comparison and regional representativeness

2017 ◽  
Author(s):  
Xiufeng Yin ◽  
Shichang Kang ◽  
Benjamin de Foy ◽  
Zhiyuan Cong ◽  
Jiali Luo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Surface Ozone ◽  
Early Morning ◽  
Photochemical Reactions ◽  
Transport Processes ◽  
The Tibetan Plateau ◽  
Nam Co ◽  
Mixing Ratios ◽  
Northern Tibetan Plateau ◽  
Ozone Levels

Abstract. Ozone is an important pollutant and greenhouse gas, and tropospheric ozone variations are generally associated with both natural and anthropogenic processes. As one of the most pristine and inaccessible regions in the world, the Tibetan Plateau has been considered as an ideal region for studying processes of the background atmosphere. Due to the vast area of the Tibetan Plateau, sites in the southern, northern and central regions exhibit different patterns of variation in surface ozone. Here, we present long-term measurements for ~ 5 years (January 2011 to October 2015) of surface ozone mixing ratios at Nam Co Station, which is a regional background site in the inland Tibetan Plateau. An average surface ozone mixing ratio of 47.6 ± 11.6 ppb was recorded, and a large annual cycle was observed with maximum ozone mixing ratios in the spring and minimum ratios during the winter. The diurnal cycle is characterized by a minimum in the early morning and a maximum in the late afternoon. Nam Co Station represents a background region where surface ozone receives negligible local anthropogenic emissions. Surface ozone at Nam Co Station is mainly dominated by natural processes involving photochemical reactions and potential local vertical mixing. Model results indicate that the study site is affected by the surrounding areas in different seasons and that air masses from the northern Tibetan Plateau lead to increased ozone levels in the summer. In contrast to the surface ozone levels at the edges of the Tibetan Plateau, those at Nam Co Station are less affected by stratospheric intrusions and human activities which makes Nam Co Station representative of vast background areas in the central Tibetan Plateau. By comparing measurements at Nam Co Station with those from other sites in the Tibetan Plateau and beyond, we aim to expand the understanding of ozone cycles and transport processes over the Tibetan Plateau. This work may provide a reference for model simulations in the future.

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