Greenhouse gases emissions in rivers of the Tibetan Plateau

Abstract

Greenhouse gases (GHGs) emissions from streams are important to regional biogeochemical budgets. This study is one of the first to incorporate stream GHGs (CO2, CH4 and N2O) concentrations and emissions in rivers of the Tibetan Plateau. With one-time sampling from 32 sites in rivers of the plateau, we found that most of the rivers were supersaturated with CO2, CH4 and N2O during the study period. Medians of partial pressures of CO2 (pCO2), pCH4 and pN2O were presented 864 μatm, 6.3 μatm, and 0.25 μatm respectively. Based on a scaling model of the flux of gas, the calculated fluxes of CO2, CH4 and N2O (3,452 mg-C m2 d−1, 26.7 mg-C m2 d−1 and 0.18 mg-N m2 d−1, respectively) in rivers of the Tibetan Plateau were found comparable with most other rivers in the world; and it was revealed that the evasion rates of CO2 and CH4 in tributaries of the rivers of the plateau were higher than those in the mainstream despite its high altitude. Furthermore, concentrations of GHGs in the studied rivers were related to dissolved carbon and nitrogen, indicating that riverine dissolved components could be used to scale GHGs envision in rivers of the Tibetan Plateau.

Physical-controlled CO<sub>2</sub> effluxes from reservoir surface in the upper Mekong River Basin: a case study in the Gongguoqiao Reservoir

“…There was no data insofar from the origin of the Mekong River. But the research on three rivers on the Tibetan Plateau shows a median pCO2 of 864 µatm, which was comparable to the values in the GGQ (Qu et al, 2017).…”

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

“…Twenty milliliters of N 2 was added to the syringe. The syringe was then shaken (underwater to maintain constant temperature) for 2 min to equilibrate the headspace with the water sample (Kling et al, ; Qu, Aho, et al, ). A 15 mL of headspace sample was then injected into a vaccumed airtight Exetainer vial (Labco Exetainer®, UK).…”

Impact of Land Cover Types on Riverine CO2 Outgassing in the Yellow River Source Region

“…In a permafrost covered region, the riverine pCO 2 exhibited a statistically significant and negative linear relationship with pH (Table 1), which is likely because the dissolved CO 2 itself acts as an acid in water [42]. In poorly buffered systems like the YRSR, pH can be a strong indicator of the dissolved CO 2 [14,19]. The DOC concentrations in the permafrost rivers (mean: 5.0 ± 2.4 mg L −1 ) were relatively higher than in the glacier rivers (mean: 3.6 ± 1.1 mg L −1 ) and the grassland rivers (4.6 ± 2.3 mg L −1 ), but were comparable to the peatland rivers of 5.1 ± 3.7 mg L −1 .…”

“…Additionally, with increasing temperature, the carbon stored in permafrost layers and glaciers are likely to be mineralized and emitted into the atmosphere from river networks [16,18]. Recent studies on the Yellow River source Region (YRSR) showed inconsistent findings from a carbon source [19] to a carbon sink [20].…”

“…For the upper Yellow River on the Tibetan Plateau, Ran et al [20] tentatively calculated its pCO 2 from pH, alkalinity, and water temperature and further estimated its FCO 2 by using a model of Alin et al [24]. Qu et al [19] have assessed the pCO 2 of the alpine rivers on the eastern Tibetan Plateau by using the headspace method and estimated their FCO 2 with a model of Raymond et al [25], but only for the permafrost and grassland regions. However, there are no seasonal and spatially resolved field-based direct measurements of CO 2 emissions from these alpine rivers, which has prohibited a comprehensive understanding of the spatial and temporal dynamics of their riverine CO 2 outgassing.…”