Aged dissolved organic carbon exported from rivers of the Tibetan Plateau

Qu, Bin; Sillanpää, Mika; Li, Chaoliu; Kang, Shichang; Stubbins, Aron; Yan, Fangping; Aho, Kelly S.; Zhou, Feng; Raymond, Peter A.

doi:10.1371/journal.pone.0178166

Cited by 38 publications

(37 citation statements)

References 46 publications

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“…In addition, the δ 13 C signature of organic carbon also provides evidence about its source. The δ 13 C of organic carbon in soil samples collected from the TP was À25.4 ± 0.6‰ (Table S3), similar to those of DOC from Tibetan river water (À25.1-25.8‰; Qu et al, 2017) and depleted relative to Nam Co WSOC (δ 13 C = À21 ± 3‰; Table 1), providing further evidence that Nam Co WSOC was not derived from local soils. Enrichment of organic carbon in 13 C can occur in the atmosphere due to both aging processes (Narukawa et al, 1999) and photochemical reactions (Miller & Zepp, 1995;Mladenov, Alados-Arboledas, et al, 2011) altering the original source δ 13 C signature of organic carbon.…”

Section: Sources Of Wsocmentioning

confidence: 57%

Fossil Fuel Combustion Emission From South Asia Influences Precipitation Dissolved Organic Carbon Reaching the Remote Tibetan Plateau: Isotopic and Molecular Evidence

Chen

Kang

et al. 2018

JGR Atmospheres

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The dissolved organic carbon in precipitation (water‐soluble organic carbon, WSOC) can provide a carbon subsidy to receiving ecosystems. The concentrations, isotopic signatures (δ13C/Δ14C), and molecular signatures (transform ion cyclotron mass spectrometry) of WSOC being delivered to Nam Co—a remote site on the inland Tibetan Plateau (TP)—were compared to those of WSOC in the snowpack, and in wet deposition from urban cities fringing the TP. The average WSOC concentration at Nam Co (1.0 ± 0.9 mg C L−1) was lower than for the large cities (1.6 to 2.3 mg C L−1) but higher than in the snowpack samples (0.26 ± 0.09 mg C L−1). Based upon radiocarbon data, it is estimated that 15 ± 6% of Nam Co WSOC was fossil derived, increasing to 20 ± 8% for snowpack WSOC, 29 ± 4% for Lhasa WSOC, and 34 ± 8% for the three cities. Transform ion cyclotron mass spectrometry results revealed that the abundance of dissolved black carbon and sulfur‐containing molecules of WSOC increased in the order Nam Co < snow pack < urban. The enrichment in 14C and depletion in dissolved black carbon and sulfurous organic molecules of Nam Co WSOC was suggestive of low, but still detectable inputs of fossil‐derived organics to WSOC on the remote TP. Backward air mass trajectories for the precipitation events at Nam Co suggested that the fossil fuel contributions to WSOC in Nam Co region originated mainly from South Asia. This study provides novel radiocarbon age, chemistry, and source evidence that anthropogenic WSOC is delivered to the remote TP, one of the most remote regions on Earth.

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Section: Sources Of Wsocmentioning

confidence: 57%

Fossil Fuel Combustion Emission From South Asia Influences Precipitation Dissolved Organic Carbon Reaching the Remote Tibetan Plateau: Isotopic and Molecular Evidence

Chen

Kang

et al. 2018

JGR Atmospheres

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“…Moreover, there is approximately 1.73 × 10 6 km 2 of permafrost distributed on the Tibetan Plateau, most of which is predicted to experience degradation under climate warming scenarios (Yang et al, ). Widespread permafrost degradation may trigger further deterioration locally and globally, with a loss of carbon from permafrost to the lotic and lentic water system (Qu, Sillanpaa, et al, ) or a direct carbon loss to the atmosphere, ultimately leading to increased atmospheric carbon stocks, accelerated warming, and a positive feedback to climate change (Yang et al, ).…”

Section: Resultsmentioning

confidence: 99%

Lakes on the Tibetan Plateau as Conduits of Greenhouse Gases to the Atmosphere

et al. 2018

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Lakes play an important role in the global carbon cycle, and littoral zones of lakes are potential hotspots of greenhouse gas production. In this study, we measured the partial pressures of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) in the littoral zones of 17 lakes on the Tibetan Plateau. The littoral zones of lakes on the Tibetan Plateau were supersaturated and acted as sources of CO 2 , CH 4 , and N 2 O to the atmosphere. The average partial pressures of CO 2 , CH 4 , and N 2 O in the surface lake water were 664.8 ± 182.5, 139.8 ± 335.6, and 0.3 ± 0.1 μatm, respectively. The average diffusive fluxes (and uncentainty intervals) of these three gases were 73.7 (0.9-295.3) mmol · m À2 · day À1 , 5.2 (0.0008-45.9) mmol · m À2 · day À1 , and 6.5 (0.07-20.9) μmol · m À2 · day À1 , respectively. The diffusive fluxes of CO 2 in lakes were significantly correlated with dissolved organic carbon, dissolved organic nitrogen, salinity, and water temperature. The diffusive fluxes of N 2 O were significantly correlated with lake water depth. However, no relationships were found between environmental factors and the CH 4 diffusive flux at the scale of this study. CO 2 exchange with the atmosphere from saline lakes was found to be higher than from freshwater lakes with equivalent CO 2 concentrations by a factor of 2.5 due to chemical enhancement of the gas transfer velocity. Therefore, further study with enhanced spatiotemporal resolution and breadth is needed to better understand the important role played by lakes on the Tibetan Plateau in both regional and global carbon cycles.

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“…As the glaciers on the TP retreat, highly bioavailable DOM may provide additional nutrients to downstream environments and amplify the trend of eutrophication of lotic and lacustrine ecosystems. Furthermore, the rivers on the TP have been shown to transport dissolved organic carbon from thawing permafrost areas (Qu et al, 2017), which is likely rapidly degraded via Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-50 Manuscript under review for journal Biogeosciences Discussion started: 20 March 2019 c Author(s) 2019. CC BY 4.0 License.…”

Section: Enhanced Water Availability Controls Changes In Lake Water Cmentioning

confidence: 99%

Reviews and syntheses: How do abiotic and biotic processes respond to climatic variations at the Nam Co catchment (Tibetan Plateau)?

Anslan¹,

Azizi-Rad²,

Buckel³

et al. 2019

Preprint

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Abstract. The Tibetan Plateau (TP) is the largest alpine plateau on Earth and plays an important role in global climate dynamics. On the TP, climate change is happening particularly fast, with an increase in air temperature twice the global average. The particular sensitivity of this high mountainous environment allows the observation and tracking of abiotic and biotic feedback mechanisms. Closed lake systems, such as the Nam Co on the central TP represent important natural laboratories for tracking past and recent climatic oscillations, as well as geobiological processes and interactions within their respective catchments. This review gives an interdisciplinary overview of modern and paleoenvironmental changes, focusing on Nam Co as model system. In the catchment area, the steep rise in air temperature forced glaciers to melt, leading to a rise in lake levels and changes in water chemistry. Some studies base their conclusions on inconsistent glacier inventories but an ever-increasing deglaciation and thus higher water availability have persisted over the last decades. The enhanced water availability causes translocation of sediments, nutrients and dissolved organic matter to the lake, as well as higher carbon emissions to the atmosphere. The intensity of grazing has a significant effect on CO2 fluxes, with moderate grazing enhancing belowground allocation of carbon while adversely affecting the C-sink potential through reduction of above- and subsurface biomass at higher grazing intensities. Furthermore, increasing pressure from human activities and livestock grazing are enhancing grassland degradation processes, thus shaping biodiversity patterns in the lake and catchment. The environmental signal provided by taxon-specific analysis (e.g. diatoms and ostracods) in Nam Co have revealed profound climatic fluctuations between warmer/cooler and wetter/drier periods since the late Pleistocene and an increasing input of freshwater and nutrients from the catchment in recent years. Based on the reviewed literature, we outline perspectives to further understand the effects of global warming on geo- and biodiversity and their interplay in the Lake Nam Co, which acts as a case study for potentially TP-wide processes that are currently shaping the earth&#8217;s future.

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Aged dissolved organic carbon exported from rivers of the Tibetan Plateau

Cited by 38 publications

References 46 publications

Fossil Fuel Combustion Emission From South Asia Influences Precipitation Dissolved Organic Carbon Reaching the Remote Tibetan Plateau: Isotopic and Molecular Evidence

Fossil Fuel Combustion Emission From South Asia Influences Precipitation Dissolved Organic Carbon Reaching the Remote Tibetan Plateau: Isotopic and Molecular Evidence

Lakes on the Tibetan Plateau as Conduits of Greenhouse Gases to the Atmosphere

Reviews and syntheses: How do abiotic and biotic processes respond to climatic variations at the Nam Co catchment (Tibetan Plateau)?

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