Supplementary material to "Controls on the distribution of the soil organic matter in mountain permafrost regions on the north Qinghai-Tibet Plateau"

Abstract. It has been known a large amount of soil organic carbon (SOC) have been accumulated over thousands of years and stored at considerable depths in permafrost regions, which could extent down tens of meters. Although the vegetation plays an important role in the distribution of SOC in upper 1 or 2 m soils, little is known about the determines of the organic carbon pools below these depths. We hypothesized that the SOM distribution and its chemical characteristics for different depths were determined by vegetation types and soil texture in mountain permafrost. To test the hypothesis, ten boreholes which were about 20 m depth under alpine swamp meadow (ASM), alpine meadow (AM) and alpine steppe (AS) were drilled in the permafrost regions on the northern Qinghai Tibetan Plateau. The results showed that the SOC stocks were highest over ASM, and lowest over AS for different depths. The soil textures were mainly silt loam over ASM, while varied with sandy loam, silt loam, and sand in AM. All the soils with higher fine-fractions have higher SOC contents than that in coarse soils. Meanwhile, the C / N ratios and carbon isotopes suggested that the SOC pools accompanied with fine-fractions soils under swamp meadow are more decomposable than those of coarse soils. Our results suggest and both the SOC stocks distribution and the chemical nature of organic matter are determined by the soil texture and vegetation types, and this rule is applicable for SOC distribution for the 20 m depth in mountain permafrost regions.

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Analysis of Raindrop Size Distribution Characteristics in Permafrost Regions of the Qinghai–Tibet Plateau Based on New Quality Control Scheme

Water ◽

10.3390/w11112265 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2265 ◽

Cited By ~ 1

Author(s):

Ma ◽

Zhao ◽

Yang ◽

Xiao ◽

Zhang ◽

...

Keyword(s):

Particle Size ◽

Quality Control ◽

Rain Rate ◽

Tibet Plateau ◽

Frozen Ground ◽

Fall Velocity ◽

Raindrop Size Distribution ◽

Raindrop Size ◽

Qinghai Tibet Plateau ◽

Permafrost Regions

Raindrop size distribution (DSD) can reflect the fundamental microphysics of precipitation and provide an accurate estimation of its amount and characteristics; however, there are few observations and investigations of DSD in cold, mountainous regions. We used the second-generation particle size and velocity disdrometer Parsivel2 to establish a quality control scheme for raindrop spectral data obtained for the Qinghai–Tibet Plateau in 2015. This scheme included the elimination of particles in the lowest two size classes, particles >10 mm in diameter and rain rates <0.01 mm∙h−1. We analyzed the DSD characteristics for different types of precipitation and rain rates in both permafrost regions and regions with seasonally frozen ground. The precipitation in the permafrost regions during the summer were mainly solid with a large particle size and slow fall velocity, whereas the precipitation in the regions with seasonally frozen ground were mainly liquid. The DSD of snow had a broader drop spectrum, the largest particle size, the slowest fall velocity, and the largest number of particles, followed by hail. Rain and sleet shared similar DSD characteristics, with a smaller particle size, slower velocity, and smaller number of particles. The particle concentration for different classes of rain rate decreased with an increase in particle size and decreased gradually with an increase in rain rate. Precipitation with a rain rate >2 mm∙h−1 was the main contributor to the annual precipitation. The dewpoint thresholds for snow and rain in permafrost regions were 0 and 1.5 °C, respectively. The dewpoint range 0–1.5 °C was characterized by mixed precipitation with a large proportion of hail. This study provides valuable DSD information on the Qinghai–Tibet Plateau and can be used as an important reference for the quality control of raindrop spectral data in regions dominated by solid precipitation.

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Impact process and mechanism of summertime rainfall on thermal–moisture regime of active layer in permafrost regions of central Qinghai–Tibet Plateau

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.148970 ◽

2021 ◽

pp. 148970

Author(s):

Zhang Mingli ◽

Wen Zhi ◽

Li Desheng ◽

Chou Yaling ◽

Zhou Zhixiong ◽

...

Keyword(s):

Active Layer ◽

Tibet Plateau ◽

Moisture Regime ◽

Impact Process ◽

Qinghai Tibet Plateau ◽

Permafrost Regions

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

Biogeosciences ◽

10.5194/bg-15-6637-2018 ◽

2018 ◽

Vol 15 (21) ◽

pp. 6637-6648 ◽

Cited By ~ 9

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.

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