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Oases and deserts generally act as a landscape matrix and mosaic in arid and semiarid regions. The significant difference in thermal and dynamic characteristics between an oasis and desert surface will result in oasis–desert interaction. Specifically, this refers to the interaction between an oasis and desert system via the exchange of momentum, energy, water, and carbon, which can lead to a series of microclimate effects that affect the structure of the atmospheric boundary layer, changes in carbon sources and sinks in an oasis, and the local ecological environment. Therefore, studying water, heat, and carbon exchange is significant to achieve the goals of carbon peaking and carbon neutrality in oasis–desert areas and support the ecological security and sustainable development of oases. To monitor energy, water vapor, and carbon exchange between the land surface and atmosphere, a land surface process integrated observatory network was established in the oasis–desert area in the middle and lower reaches of the Heihe River basin, the second largest endorheic basin in China. In this study, we present a suite of observational datasets from artificial and natural oasis–desert systems that consist of long-term energy, water vapor, carbon and methane fluxes as well as auxiliary data involving hydrometeorology, vegetation, and soil parameters from 2012 to 2021. Half-hourly turbulent flux data were acquired by an eddy covariance system and scintillometer. The hydrometeorological data (including radiation, soil heat flux, and soil temperature profiles; gradients of air temperature and humidity and of wind speed and direction; and air pressure, precipitation, and soil moisture profiles) were observed from automatic weather stations with a 10 min average period as well as the groundwater table data. Moreover, vegetation and soil parameters were also supplemented in the datasets. Careful data processing and quality control were implemented during data production, including data collection, processing, archiving, and sharing. The current datasets can be used to explore the water–heat–carbon process and its mechanism of influence; to calibrate and validate related remote-sensing products; to simulate energy, water vapor, and carbon exchange in oasis and desert areas; and to provide references and representatives for other similar artificial and natural oases along the "Silk Road". The data are available from the National Tibetan Plateau Third Pole Environment: 10.11888/Terre.tpdc.300441 (Liu et al., 2023). [ABSTRACT FROM AUTHOR]

Oases and deserts generally act as a landscape matrix and mosaic in arid/semiarid regions. The significant difference of thermal and dynamic characteristics between oasis and desert surface will result in oasis-desert interaction. That is, the interaction between oasis and desert system through the exchange of momentum, energy, water and carbon, which can lead to a series of microclimate effects that affect the structure of the atmospheric boundary layer, changes of carbon sources/sinks in oasis and the local ecological environment. Therefore, studying water, heat and carbon exchange is significant for achieving the goals of carbon peaking and carbon neutrality in oasis38 desert areas and supporting the ecological security and sustainable development of oases. To monitor energy, water vapor and carbon exchange between the land surface and atmosphere, a land surface process integrated observatory was established in the oasis-desert area in the middle and lower reaches of the Heihe River Basin, the 2nd largest endorheic basin in China. In this study, we present a suite of observational datasets in artificial and natural oases-desert systems, which consist of long-term energy, water vapor, carbon/methane fluxes, and auxiliary data involving hydrometeorology, vegetation and soil parameters from 2012 to 2021. Half-hourly turbulent flux data were acquired by an eddy covariance system and scintillometer. The hydrometeorological data, including radiation, soil heat flux and soil temperature profile, gradient of air temperature/humidity and wind speed/direction, air pressure, precipitation and soil moisture profiles, were observed from automatic weather stations with a 10-minute average period as well as the groundwater table data. Moreover, vegetation and soil parameters were also supplemented in the datasets. Careful data processing and quality control are implemented during data production, including data collection, processing, archiving and sharing. The current datasets can be used to explore the water-heat-carbon process and its influence mechanism, calibrate and validate related remote sensing products, simulate energy, water vapor and carbon exchange in oasis and desert areas, and provide references and representatives for other similar artificial and natural oases along the Silk Road. The datasets are available from the National Tibetan Plateau Third Pole Environment. [ABSTRACT FROM AUTHOR]

It is difficult to quantify the amount of groundwater inflow on the Tibetan Plateau (TP), yet it can be critically important for sustaining lake water balance. Here we show that most endorheic lakes on the western TP exhibited considerable water level increase during the ice‐covered period, which contrasts with lakes in other regions of the TP. An analysis of lake water balance attributes this water surplus to significant groundwater inflow, which is estimated to be about 59%–66% of total inflow into lakes. The groundwater inflow occurred after the 2000s, which is consistent with the rapid lake expansion and significant increase in precipitation. We suggest that the groundwater inflow is mainly related to large‐scale active faults in the limestone bedrock and sufficient meltwater from high elevations. Our results imply that groundwater may be deeply involved in the water cycle and modify the seasonal and inter‐annual lake variations on the western TP. Plain Language Summary: Although groundwater inflow can be critically important for maintaining lake water balance, it is difficult to quantify its contribution to endorheic lakes on the Tibetan Plateau (TP). Lake‐level changes during the ice‐covered period (December to May) can be taken as a good indicator of groundwater inflow into endorheic lakes because there is very limited snowfall, surface runoff, and sublimation. Here we show that most endorheic lakes on the western TP exhibited considerable water level increase during the ice‐covered period, which contrasts with lakes in other regions of the TP. An analysis of lake water balance indicates that this water surplus was mainly attributed to significant groundwater inflow. The occurrence of groundwater inflow is consistent with the significant increase in precipitation and rapid lake expansion after the 2000s on the western TP. The formation of groundwater inflow may be mainly associated with the regional geological setting. Large‐scale active faults in the limestone bedrock increases lake basin permeability, and together with sufficient meltwater from glaciers and snow in high elevations contribute to groundwater inflow into these lakes. Our results imply that groundwater may be deeply involved in the water cycle and modify the seasonal and inter‐annual lake variations on the western TP. Key Points: Lake level increased considerably on the western Tibetan Plateau during the ice‐covered period, accounting for half of annual lake‐level increaseLake water surplus during the ice‐covered period is mainly attributed to significant groundwater inflowThe occurrence of groundwater inflow after the 2000s is consistent with the decadal variability of summer precipitation [ABSTRACT FROM AUTHOR]

Purpose : Soil organic carbon (SOC) dynamics strongly affect the terrestrial carbon balance, and stable isotopic measurements provide detailed information about SOC cycling. However, the response of δ13C and SOC to climatic factors is still not well known in high alpine regions. Methods: In this study, soil δ13C and SOC in vertical soil profiles were analysed at alpine grassland sites along four precipitation gradients (350–400, 450–500, 550–600, and 650–700 mm) on the eastern Qinghai–Tibetan Plateau. The β value is defined by the slope of the linear regression relating soil δ13C to the logarithm of SOC, and the higher β values represent slower SOC turnover. Results: The SOC concentration tended to decline with increasing soil depth from 0 to 40 cm, while δ13C was enriched in alpine grassland on the eastern Qinghai–Tibetan Plateau. The δ13C values in the 650–700-mm class were relatively depleted compared with other precipitation classes. Redundancy analysis (RDA) showed that altitude was the most important factor—explaining 20.9% of the variation in 13C in surface soil (0–10 cm), followed by mean annual air temperature (MAT) (17.1%) and mean annual precipitation (MAP) (16.9%). MAT and altitude were the main factors controlling δ13C and β values. MAP did not significantly affect SOC distribution, but lower δ13C and β values occurred with higher precipitation. Correlations between SOC content and MAT increased significantly after removing relationships with MAP. Conclusions: The results indicate that faster SOC decomposition may not necessarily lead to SOC losses on the eastern Tibetan Plateau given current conditions. Future research should consider the effects of interactions between warmer and wetter conditions (predicted under climate change) on SOC content and turnover. [ABSTRACT FROM AUTHOR]

Anthropogenic cadmium (Cd) in alpine soils is mainly from long-range atmospheric transport. Because of the high toxicity and mobility, whether the accumulation of Cd in the soils threats to ecosystem safety remains unclear. The fractions of soil Cd along three altitudinal transects on Gongga Mountain were analyzed to decipher the drivers on its mobility, and its contamination and health risk were assessed. The concentrations of Cd in the organic (O) and mineral (A) horizons were significantly higher on the eastern and southern transects than the western transect. The Cd fractions in the two horizons dominated by acid-soluble and reducible Cd. Soil organic matter and pH modulated the mobilization of soil Cd. Cadmium reached a moderate contamination level on the eastern and southern transects, but no or slight contamination on the western transect. The soil Cd had a low non-carcinogenic risk and no carcinogenic risk despite of adults or children. [ABSTRACT FROM AUTHOR]

Because of its unique geographical location, the Tibetan Plateau has been widely studied in geological research. Several studies revealed the geological structure and evolutionary process of the lithosphere deep beneath the northeastern Tibetan Plateau; however, the deep structural characteristics of the Zhangye Basin, which is in the middle of the Hexi Corridor at the junction of the northeastern Tibetan Plateau and Alxa Block, have not been widely examined. To better understand the geodynamics of the Zhangye Basin, studies are needed to investigate the tectonic mechanism of the northeastern Tibetan Plateau. To determine its subsurface structure, 46 broadband magnetotelluric survey stations were deployed across the basin in 2020. The crustal electrical structure of the basin was modeled via three-dimensional nonlinear conjugate gradient inversion. The results of this inversion revealed a low-resistivity zone in the middle-lower crust of the basin, which was characterized as an intracrustal decollement, thus suggesting decoupling deformation of the crust interior. This conductive body may have formed during continuous growth of the Tibetan Plateau, which may have expanded northeastward below the Hexi Corridor and Helishan Fault. The latter may have partly underthrust southwestward in the lower part of the Hexi Corridor and Tibetan Plateau. These results regarding geothermal formation of the Zhangye Basin improve the understanding of its underground structure and may guide the future development of geothermal resources in this area. • The Zhangye Basin was modeled using three-dimensional inversion. • A conductive body in the middle and lower crust indicates intracrustal decollement. • The conductive body may have formed during the expansion of the Tibetan Plateau. • The Zhangye Basin has the potential for geothermal development. [ABSTRACT FROM AUTHOR]

The mid-chain and long chain n -alkanes in sediments of Genggahai Lake, on the northeastern Tibetan Plateau, have been assigned as being predominantly from aquatic plants. Thus, at the lake, compound specific hydrogen isotopic data for mid- and long chain n -alkanes (δD n -alkanes ) are indicators of the variation in lake water δD (δD LW ). Genggahai δD LW is determined by the local meteoric water δD (δD MW ) and by lake surface evaporation, as evidenced by modern observational data and the broad correlation between Genggahai δD LW and average lake water depth during the past 15 ka, with more negative δD LW values corresponding to greater average water depth. As demonstrated by the mid- and long chain δD n -alkanes data, the most negative interval of Genggahai δD LW was during the early Holocene. An overall trend towards more positive values from the early to the late Holocene clearly indicates the long term evolutionary history of local δD MW , which could be related to the intensity of the Indian summer monsoon (ISM) via the “rainfall amount effect”. Therefore, the record of δD LW at Genggahai during the past 15 ka, which resembles that of stalagmite δ 18 O records from the core ISM region, apparently reflects the long term evolution of ISM intensity. Furthermore, several short-term positive excursions in Genggahai δD LW values during the late Holocene reflect enhanced lake surface evaporation via an “isotopic enrichment” mechanism that apparently resulted from periods of weakened ISM intensity. Our results highlight the fact that unambiguous source determination of n -alkanes is vital for determining the paleoclimatic significance of lacustrine δD n -alkanes data. [ABSTRACT FROM AUTHOR]

In this paper, recent glacier and lake changes research on the Tibetan Plateau was reviewed. Emphasis was placed on a discussion of the relationship between glacier shrinkage and lake change. In the context of global climate change, the glaciers of the Tibetan Plateau have generally retreated, while the lakes have generally expanded. First, the research on glacial terminal retreat, glacial area and volume variations across the Tibetan Plateau over the last few decades are reviewed and analyzed; the temporal-spatial change characteristics of the glaciers are discussed. Secondly, the lake area, volume and water level changes are reviewed and analyzed; the temporal-spatial change characteristics of the glaciers are discussed. The results indicate that the retreat speed in the outer edge of the Tibean Plateau was overall faster than that in the inland area. The areas and water levels of the lakes that are fed by glacial water increased. Finally, the limitations of the present studies and future work are discussed. [ABSTRACT FROM AUTHOR]

Mantle tectonics, such as asthenospheric upwelling and lithospheric decoupling, usually controls subsequent fluid formation and migration from deep to shallow levels in the lower lithosphere and promotes rock failure and deformation. Based on the concept whereby the fluid migration location defines the structural inheritance, we aim to relate crustal processes to mantle tectonics using fluids revealed by a new magnetotelluric (MT) array across the Ailao Shan-Red River belt. As imaged via a 3D resistivity model, two lower-lithospheric conductive anomalies are determined as consistent with the Dian-Qiong (DQ) suture and Song Da (SD) belt and interpreted to contain interconnected melt. Because potassic magmatism was enabled by partial melting in the lower lithosphere, we could infer that the DQ and SD have reworked as the major fluid migration channels. Fluid migration is considered to drive lithospheric decoupling at a low-viscosity conductive layer, which is inferred feeding by aqueous and melt fluids originating from the two channels and diffusing at depths from 15 to 20 km. Constrained by the geochronology results, this weak layer could have provided convenience to induce the entirely upper crustal translation-rotation within the time interval between potassic magmatism and strike-slip of the Red River fault. This translation-rotation process is inherited from the underlying mantle processes and may further be remotely affected by the upper crustal movement of the Tibetan Plateau, conforming with the crustal rotation observed to the north of our study region. This work provides a compelling example of the tectonic control of the mantle on inherited responses in the crust. Plain Language Summary Crustal deformation is usually controlled by mantle tectonic processes, especially the southeastern Tibetan Plateau. Some models have proposed that lithospheric shearing and lower-crustal flow have controlled the crustal deformation in the Cenozoic. However, crustal rotation models show less possibility of a channel flow and relate the crustal deformation to the remote effect of India-Asia collision. Our study investigates above hypotheses by imaging the electrical resistivity of rocks beneath the major Red River Fault area in southeastern Tibet, using magnetotelluric data with high quality in a dense array. The lithosphere of the study area is interpreted to have been divided into two horizontal systems by a fluid diffusion layer at the bottom of upper crust. Resistivity low in the lower lithosphere is inferred due to partial melting of deep lithosphere and reworking of the paleo sutures in the Late Cenozoic, which have spread at the bottom of upper crust. Rather than the channel flow, this fluid migration process sensitively reflected in our model relates the mantle tectonics to crustal rotation by providing rheological conditions. We, hence, propose an inherited structure model featured by lithospheric decoupling and upper-crustal translation-rotation that may occur before the major strike-slip event. [Display omitted] • A new 3D model reveals electrical structures on the southeastern Tibetan Plateau. • The Red River fault is discontinuous at a depth of ∼20 km and may move away from the palaeo-suture. • Palaeo-suture was reconstructed into two activated zones and reworked as channels for fluid migration. • Fluid migration has driven the lithospheric decoupling and upper crustal inheritance. • The upper crust experienced a translation-rotation process before the internal strike-slip event. [ABSTRACT FROM AUTHOR]

Per-and polyfluoroalkyl substances (PFASs) are omnipresent globally and received increasing attention recently. However, there are limited data on PFASs in the Tibetan Plateau (TP), a remote high-altitude mountain region, which is regard as an important indicator region to study long-range transport behaviors of contaminants. This study investigates the occurrence, distribution, partitioning behavior, and sources of 26 PFASs in water and sediments from the four lakes of TP. The ΣPFAS concentrations ranged from 338 to 9766 pg L-1 in water, and 12.2–414 pg g-1 dry weight in sediments. Perfluorobutanonic acid (PFBA) and perfluorooctane sulfonate (PFOS) were detected in all samples. Qinghai Lake had the highest ΣPFAS concentrations in both water and sediments, while the Ranwu Lake had the lowest. The functional groups and CF 2 moiety units were investigated as essential factors influencing the partition behavior. Principal component analysis (PCA) combined back-trajectory was used to infer possible sources of PFASs. The results suggested that the main source of PFASs in Yamdrok Lake, Namco Lake, and Ranwu Lake on southern TP were mainly originated from South Asia via long-range atmospheric transport (LRAT); while for the Qinghai Lake of northern TP, LRAT, local emissions, and tourism activities were the primary sources of PFASs. [Display omitted] • 26 PFASs in different alpine lakes in the Tibetan Plateau (TP) were analyzed. • Short-chain PFCAs were dominant in water and long-chain PFSAs in sediments. • ADONA and 6:2 FTS were firstly detected in the TP. • Log K d and log K oc values of PFASs were correlated with carbon chain length. • Potential sources of PFASs in the TP lakes were identified. [ABSTRACT FROM AUTHOR]

Two atmospheric circulation systems, i.e., the mid-latitude Westerlies and the East Asian summer monsoon (EASM), dominate climate change in the NE Tibetan Plateau. However, controversy remains with regard to the climatic boundary between these westerly and monsoon regimes. In this paper, detailed rock magnetic and geochemical Rb/Sr analyses for a larger number of surface soils from a wide area in the NE Tibetan Plateau are presented. They show that surface soils in this region evince relatively significant regional variations in magnetic properties and geochemical characteristics. The magnetic parameters χ fd, χ ARM and geochemical Rb/Sr ratios exhibit higher values in EASM-controlled (humid) areas, and lower values in Westerlies-influenced (arid) areas. These characteristics indicate that such variations in χ fd, χ ARM and Rb/Sr ratios can be regarded as effective indicators of the degree of pedogenesis and weathering in the NE Tibetan Plateau. Our results also demonstrate that the climatic boundary between the westerly and monsoon regimes approximately overlaps with the boundary of highland meadow and temperate steppe desert/desert in NW China. [ABSTRACT FROM AUTHOR]