Tibetan Plateau In China Research Articles

Potential distribution and habitat suitability of Picea crassifolia with climate change scenarios

The Qinghai–Tibet Plateau in China is a region strongly impacted by climate change, yet its effects on the keystone endemic forest species Picea crassifolia Kom. are unknown. Understanding the changes in potential distribution and habitat suitability of P. crassifolia forest with climate change will contribute to water conservation, forest management, and ecological protection in the upper reaches of the Yellow River. A total of 129 records of species distribution data and 19 environmental variables were chosen for modeling. The MaxEnt (maximum entropy) model was used to analyze the main environmental factors affecting the potential distribution of P. crassifolia in two periods (2050s and 2070s) and four representative emission pathways (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5). The main results are follows: (i) the most important environmental variables affecting distribution of P. crassifolia and percentage variance explained were altitude (41.85%), precipitation of driest month (19.76%), slope (12.35%), annual precipitation (6.56%), precipitation of wettest month (5.73%), and precipitation of warmest quarter (5.12%); (ii) habitat suitability of P. crassifolia shifted to the northwest and into high-altitude areas under climate change scenarios, but its core distribution areas were concentrated in northeastern Qinghai–Tibet Plateau, Qilian Mountains, southern Ningxia, and Helan Mountains; and (iii) the total area of potential suitable habitat of P. crassifolia will change significantly in the future, and change of habitat area of not suitable, low, moderate, and high suitability exceed 60%.

Sedimentary Pediastrum record of middle–late Holocene temperature change and its impacts on early human culture in the desert-oasis area of northwestern China

Although the pattern of Holocene temperature variations in central Asia is complex, it is clear that temperature played a fundamental role in influencing humidity conditions and regional human activity. We reconstructed temperature changes using Pediastrum species data, verified by clumped isotopes (Δ47), in the carbonates of sediment cores recovered from Bosten Lake in Xinjiang Province, northwestern China. Combined with archaeological data, the results indicate an unusually warm climatic interval that peaked at ∼4.7–4.3 kyr and promoted human occupation of the Altai Mountains. The climate cooled during 4.2–4.1 kyr and 3.6–3.5 kyr, as indicated by the decrease or absence of Pediastrum simplex. These cold events may have triggered the southward human migration out of the Altai region, resulting in the widespread distribution of archaeological sites at lower latitudes, in the Tienshan Mountains, and in the desert-oasis areas of the Tarim Basin in southern Xinjiang. Our data support the notion that a series of cultural transitions across the monsoonal Loess Plateau and Tibetan Plateau of China may have been linked to temperature changes during the middle to late Holocene.

A novel mathematical method for evaluating the wellbore deformation of a diagenetic natural gas hydrate reservoir considering the effect of natural gas hydrate decomposition

Diagenetic natural gas hydrate (DNGH) is a metastable material that is widely distributed in the frozen formations of Qinghai–Tibet Plateau in China. Drilling boreholes in such frozen formations can lead to the decomposition of DNGH, which is deleterious for wellbore stability as this process can lead to a complex and uncontrollable changes in the structure of the frozen formation. In this study, a fluid–solid–heat coupling mathematical model was developed for evaluating the wellbore deformation of a DNGH reservoir while considering the effect of DNGH decomposition. This mathematical model includes the kinetic equations describing DNGH decomposition, rock skeleton deformation equations, seepage field equations, temperature field equations, dynamic porosity equations, and dynamic permeability equations. COMSOL Multiphysics software was used to solve this new mathematical model and the deformation of a real wellbore in the permafrost of Qilian Mountains was analyzed. Two drilling methods were considered in the numerical simulation. The results indicate that: 1) the stress redistribution that occurs immediately after drilling the DNGH reservoir stabilizes rapidly. The maximum stress observed was at an angle of 135° with respect to the minimum horizontal principal stress. 2) The stress in the wellbore surrounding rock under the condition of micro-overbalanced drilling stabilizes more rapidly, and the values are higher compared with the results of micro-underbalanced drilling. 3) The most significant compression deformation occurs in the direction of minimum stress and the displacement in the wellbore surrounding rock simulated by micro-overbalanced drilling increases more rapidly and produces lower stress compared to that simulated with micro-underbalanced drilling.

Microbiome analysis reveals soil microbial community alteration with the effect of animal excretion contamination and altitude in Tibetan Plateau of China

The fertile forages in the Tibetan Plateau provide natural conditions for animal husbandry, whereas it is still unclear that whether animal excretion can result in the alteration of soil microbial community. Therefore, this study was performed to investigate the impact of animal excretion contamination and land altitude on the soil microbial community in different grazing areas of Tibetan Plateau. A total of 1160,190 high-quality valid sequences and 25,478 operational taxonomic units were achieved from 18 samples at three different altitude sites (Linzhi, Rikaze and Shannan). Here, we found excremental contamination did not alter the richness and diversity of soil microbial community, but it resulted in a significant alteration in the proportion of some bacteria. Specifically, the proportion of Proteobacteria in the LZa was obviously increased, whereas Gemmatimonadetes was significantly decreased as compared to LZe. Moreover, significant difference can also be observed in Verrucomicrobia between RKZe and RKZa. Remarkably, we also found that excremental contamination significantly decreased the abundance of some bacterial genera, such as Sphingopyxis, Polycyclovorans, Singulisphaera Cohnella, Polycyclovorans, Defluviicoccus, and Arthrobacter, which were closely related to soil health, pollutant degradation, and nutrient metabolism. Importantly, excremental contamination increased the proportion of harmful and beneficial bacteria in soil, such as the percentage of Acidibacter, Gemmatimonadaceae and Pajaroellobacter increased, while the ratio of Pontibacter, Flavisolibacter, Parasegetibacter, and Niastella decreased. Remarkably, soil samples collected from different altitude sites also displayed different soil microbial community structures. Our results demonstrated that excremental contamination could alter the soil microbial community structure and affect the normal function of the soil by affecting the proportion of harmful bacteria to beneficial bacteria. Moreover, this study can also provide a theoretical basis for the establishment of a supervision system for soil quality in Tibet.

Structural properties of shear zone materials of the Neogene soft-rock landslides in the northeastern margin of the Tibetan Plateau

Seven landslides among the 110 landslides on the northeastern margin of the Tibetan Plateau in China were selected to analyze the structural development processes within the shear zones. In addition, the platy clay mineral content and mineralogical composition of the shear zone were also investigated. The samples obtained from the vertical profiles were quantitatively studied from top to bottom with respect to their material composition, pore structure, and water properties to understand the changes in the cementation and frictional properties of the shear zone. The results indicate that the structure is progressively modified by fractures, cleavage, and plasticization. Even though there is no sliding surface liquefaction, clayey particles are observed to exhibit slipping and rearrangement. The illite–montmorillonite mixed-mineral layer accumulates near sliding surface in the core zone, and the platy clay minerals are arranged along shearing direction for long shear displacement.

Identification of a novel Aichivirus D in sheep.

A novel kobuvirus was found in diarrheal fecal samples of Tibetan sheep using a viral metagenomics approach, and a full kobuvirus genome was successfully obtained by RT-PCR from a diarrheal fecal sample. The full genomic sequence was 8485 nucleotides (nt) in length with a standard picornavirus genome organization. The novel genome shares 62.9% and 77.8% nt homology with Aichivirus D1 genotype strain 1-22-KoV, and Aichivirus D2 genotype strain 2-44-KoV, respectively. According to the species classification criteria of the International Committee on Taxonomy of Viruses (ICTV), the new kobuvirus belongs to Aichivirus species D. Interestingly, compared with 2 known Aichivirus D genotype strains, the novel Aichivirus D has unique amino acid substitutions in the 5'untranslated region (-UTR), VP0, VP3, and VP1, with a recombination event in the 2C region.These characteristics make the novel Aichivirus D cluster into an independent branch in the phylogenetic tree, suggesting that strain may represent a novel genotype in Aichivirus D. Moreover, the novel Aichivirus D was detected in 9.2% (18/195) of the sheep diarrheal fecal samples from 4 farms in 3 counties of the Qinghai Tibet Plateau in China. In addition, full-length VP0, VP3, and VP1 genes were successfully obtained from 12 samples from 4 farms, and phylogenetic analysis based on these genes revealed a unique evolutionary pattern for this novel Aichivirus D strain. This study identified a novel Aichivirus D that is circulating in sheep in Qinghai Tibet Plateau in China and these findings provide a better understanding of the epidemiologic and genetic evolution of kobuviruses.

Arsenic transfer along the soil-sclerotium-stroma chain in Chinese cordyceps and the related health risk assessment.

BackgroundChinese cordyceps (Lepidoptera: Ophiocordyceps sinensis)is a larval-fungus complex. The concentration and distribution of arsenic (As) may vary during the stroma (ST) germination process and between the sclerotium (SC) and the ST. The soil-to-Chinese cordyceps system is an environmental arsenic exposure pathway for humans. We studied the As concentration in the soil, the SC, and the ST of Chinese cordyceps, and performed a risk assessment.MethodsSoil and Chinese cordyceps samples were collected from the Tibetan Plateau in China. The samples were analyzed for the total As concentration and As species determination, which were conducted by inductively coupled plasma mass spectrometry (ICP-MS) and HPLC-ICP-MS, respectively.ResultsThe concentration of total As in the soil was much higher than in SC and ST. The major As species in the soil was inorganic AsV. In SC and ST, organic As was predominant, and the majority of As was an unknown organic form. There are significant differences in the As distribution and composition in soil, SC, and ST. Our risk assessment indicated that chronic daily ingestion was higher than inhalation and dermal exposure in children and adults. The hazard index (HI) of the non-carcinogenic and cancer risks (CR) for human health were HI ≤ 1 and CR < 1 × 10−4, respectively.ConclusionThe Chinese cordyceps possesses highly-efficient detoxifying characteristics and has a significant role in As transformation during its life cycle. We found that the levels of As in soils from the habitat of Chinese cordyceps were higher than the soil background values in China, but the probability for incurring health risks remained within the acceptable levels for humans.

Association between echinococcosis-specific health literacy and behavioural intention to prevent echinococcosis among herdsmen on the Tibet Plateau in China: a cross-sectional study

BackgroundEchinococcosis is considered a neglected zoonotic disease and has been a major worldwide public health problem. Although it is known that health literacy is closely related to health behaviours and health outcomes, few studies have paid attention to echinococcosis related health literacy. This study aims to examine the association between echinococcosis-specific health literacy (ES-HL) and behavioural intention to prevent echinococcosis (BIPE) among herdsmen on the Tibet Plateauin in China.MethodsA cross-sectional study of 401 Tibetan herdsmen was conducted in Gande county of Qinghai Province, China. Participants were recruited from August to September 2018 and from February to March 2019. A self-developed questionnaire was used to measure demographic information, ES-HL and BIPE. Hierarchical regression analysis was done to identify the factors associated with BIPE.ResultsIn the hierarchical regression analysis, we entered age, sex, education level, marital state and family monthly income per capita into model 1 which explained a significant amount of variance in BIPE (Adjusted R2 change = 0.029, P = 0.006). Sex (β = − 0.125, P = 0.013) and family monthly income per capita (β = − 0.133, P = 0.009) were found to be associated with BIPE. Subsequently, the three factors of ES-HL were added to Model 1 to create Model 2. In Model 2, the two factors of ES-HL, perceived echinococcosis information support (β = 0.229, P < 0.001) and echinococcosis-specific self-management ability (β = 0.252, P < 0.001), were significantly associated with BIPE, while the information acquisition and evaluation ability factor (β =0.093, P = 0.089) was not found to be associated with BIPE. The model improved significantly when ES-HL was included (Model 2) explaining the 25.8% of variance of BIPE (Adjust R2 change =0.229, P < 0.001).ConclusionsES-HL is an important predictor of whether individuals take preventive actions against echinococcosis. An ES-HL promotion action project should be developed targeting specific populations to enhance the prevention of echinococcosis.

Transport energy consumption of rural households in the Tibetan Plateau of China

Transportation has become the world's second-largest energy-consuming sector, yet existing works mainly focus on the macro perspective and the causal relationships with social–economic–environment dimensions, leaving a significant knowledge gap at the household or individual level. Studying household-scale transport energy structure research is of great significance for exploring the driving mechanism of carbon dioxide emissions and promoting sustainable development. This study focuses on the region of the Tibetan Plateau of China. Field-based surveys and semi-structured interviews were conducted to investigate the transport energy consumption of rural households from the perspectives of sub-region (agricultural area, pastoral area, agropastoral area) and income (low-income, lower-middle-income, middle-income, upper-middle-income and high-income). On the basis of 498 samples, detailed energy consumption structures and environmental factors are presented. The authors hope that in the future, there will be more reports on household transport energy in different regions to provide a scientific basis for understanding and promoting household energy transition.

A Study on the Rock Art of the Tongtian River Basin, Tibetan Plateau of China

In recent years, the Yushu Museum has conducted a systematic investigation on the rock art of the Tongtian River Basin in its prefecture and newly discovered 1230 panels’ rock art (more than 1700 images). This paper is a statistical and comparative analysis of the newly discovered rock art. According to content and production techniques, we divided the rock art of the Tongtian River Basin into two big areas. The West Area is the upper part of the river basin, which is the area above the confluence of Tongtian River and Chumar River (Qumalai River); the East Area is the lower part of the river basin, which is from the confluence to the Batang estuary of Yushu. This area can be subdivided into three subareas. The majority of the Tongtian River Basin’s rock art is categorized as animal type. Yak and deer are respectively the main themes of the West Area and the East Area. In addition, there are other rock art types like symbol, character, pagoda, carriage and so on. The two areas have both commonalities and their own characteristics. Through the typological analysis of production techniques, in the cases of carriage rock art, and deer rock art, we think that the rock art mainly used the whole-image chiseling technique. This technique can be traced back to the Shang Dynasty; the rock art mainly chiseled linearly is dated to the early Zhou Dynasty to the Warring States Period; the rock art that was creates with the line carving technique is dated to the Warring States Period to the Western Han Dynasty; the rock art that was creates with the grind carving technique can be dated back to the Qin and Han dynasties; and the rock art mainly used scratching technique can be traced back to the Ancient Tibetan Empire Period (618-842 AD)

Potential distribution of Abies, Picea, and Juniperus species in the sub-alpine forest of Minjiang headwater region under current and future climate scenarios and its implications on ecosystem services supply

Mountain forest ecosystems provide us with life-supporting ecosystem services that are valuable for local, regional, and global communities. Ecological niche-based models have been used extensively, with remarkable success, in understanding the influence of climate change on potential distribution of species. In this study, we used maximum entropy (MaxEnt) modelling to predict the potential distribution of ecologically important tree species, Abies, Picea, and Juniperus, at the eastern edge of the Tibetan Plateau in China. The potential distribution of tree species was modelled and predicted on genus level for current and three representative concentration pathway (RCPs) based future (2050s and 2070s) climate conditions. The model performed well and gave reliable results for current and potential species’ distribution. Precipitation of wettest month was the most important environmental variable for determining the habitat suitability of all tree species, with 30.3% (Abies), 51.2% (Picea), and 57% (Juniperus) contribution to model output, respectively. Temperature seasonality, temperature annual range, and soil type also made the most significant contribution to model outputs. Model projections under current climate highlight that the total suitable habitats, which included regions with different probability of species occurrence, for Abies (3234.2 km2) was much higher than Picea (2003.7 km2) and Juniperus (1784.8 km2). However, projections of habitat suitability under current climate scenario projected onto future climate change scenarios for all concentration pathways in 2050s and 2070s, showed a clear decline in potentially suitable habitats for all three species. The shifts in geographic distributions under future climate scenarios showed an unusual pattern, with slight downward shift of the mean elevation with high habitat suitability for the occurrence of tree species in most RCPs, accompanied by a decrease in the elevational range of suitable habitats. The results of this study highlight the urgent need for forest management strategies to conserve the habitats of these species. Our study offers base-line information on the impact of climate-change on major tree species which can aid in guiding adaptation strategies for forest conservation and management in order to sustain the delivery of ecosystem services in the future.

Geological structure and failure mechanism of an excavation-induced rockslide on the Tibetan Plateau, China

Rock slope failures are controlled by a complex interplay of geological structures and anthropogenic activities. In this study, data from structural geology, rock mass characterization, and ground-based monitoring networks are integrated into a numerical model. This model is used to explore the relationships among structural features, damages, anthropogenic activities, and slope failures occurring on the Tibetan Plateau in China. In particular, a model for the interpretation of brittle tectonic structures is illustrated, which characterizes the fracture patterns and explains the role of these features in the development of rock slope instability. Additionally, the relationships between tectonic structure-related fractures and slope failure mechanisms are investigated by characterizing the rock mass damage using the geological strength index. Finally, a numerical model is developed, which integrates the available data. It is found that the tectonic structure-related fractures controlled by an anticline are primarily responsible for slope failure, while an excavation was identified as its triggering mechanism. This research can serve as a reference for studies on excavation-induced rockslides.

The Oligocene Equisetum from Qaidam Basin, Northeastern Tibetan Plateau in China and its implications

ABSTRACT Equisetum: (Equisetaceae, Equisetales) is widely distributed around the world and distinguished by obviously jointed stems with longitudinal ridges or furrows. Recently, fossil materials collected from the Shangganchaigou Formation of northwestern Qaidam Basin, China, are assigned to Equisetum based on the presence of jointed stems, longitudinal ridges, and whorls of branch scars. The current specimens are the first discovery of Equisetum in northern Tibetan Plateau and also represent the first fossil record of the genus from Oligocene in Qaidam Basin. The new discovery enriches the knowledge of the paleo-diversity of the Equisetum and indicates that the sphenophytes once existed in the northern Tibetan Plateau. Based on the fossil records in and around the Tibetan Plateau, Equisetum could survive at a higher latitude during the Palaeogene and they could only grow in lower latitude since the Neogene, which might be the result of the tectonic deformation and climatic changes in the northern plateau since the Miocene. The current fossil, together with co-existed fossils, indicate that there have been rich drainages and temperate deciduous broad-leaved forest with grass in northwestern Qaidam Basin during the Oligocene.

Vegetation and soil covariation, not grazing exclusion, control soil organic carbon and nitrogen in density fractions of alpine meadows in a Tibetan permafrost region

The accrual of soil organic carbon (SOC) and nitrogen (N) in grassland is an important management option to improve the ecosystem functions of grassland. However, how abiotic (such as grazing exclusion (GE)) and biotic factors influence SOC and N and their different fractions in Tibetan alpine meadows remains unclear. In this study, we evaluated the relative importance of abiotic and biotic factors that drive SOC and N contents in soil density fractions by performing redundancy analysis based on three long-term (10 years) fenced alpine meadows maintained in the permafrost region of the Tibetan Plateau in China. Biotic factors comprise plant aboveground biomass, cover and diversity, whereas abiotic factors include soil properties (i.e. soil moisture, pH, clay, silt, sand, total phosphorus, available phosphorus, microbial biomass carbon and N, available N, C:N ratio and C:P ratio) and GE. Site rather than GE has significant effects on the SOC and N contents. GE caused no increase in the SOC and N contents in the whole soil and fractions. Redundancy analysis showed that 96.7% of the variations in SOC and N fractions can be explained by the selected explanatory variables. Aboveground biomass, cover, soil moisture and clay contents were key factors that affected the SOC and N fractions. The SOC and N fractions were mainly explained by the interaction between vegetation and soil, followed by soil, vegetation and GE. The study highlighted the importance of considering the covariation of vegetation and soil for evaluating the SOC and N dynamics in alpine meadows. The effect of GE (such as 10 years) on the SOC and N contents in alpine meadows can be weak in the permafrost region of the Tibetan Plateau.

Determination of Inorganic Element Concentrations in Nardostachys jatamansi DC

Background:: Nardostachys jatamansi DC. is indigenous to the Himalayan regions of India and Tibetan plateau of China, and widely used as drugs for treating various neurological disorders, insomnia, hysteria and depressive illness. However, beyond the huge efforts to the organic components in N. jatamansi, the elemental contents have not been investigated, which are important for the quality control and biosafety evaluation of N. jatamansi. Objective:: In this study, we quantified the element concentrations in N. jatamansi. Methods:: Twenty-five N. jatamansi samples were collected in Sichuan, Tibet, Qinghai and Gansu provinces. The samples were digested and subjected to inductively coupled plasma optical emission spectrometer (ICP-OES) measurements. Results:: The results indicated that Al, B, Ba, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pd, Si, Sr, Ti and Zn were detected in N. jatamansi samples. The chemometrics approaches indicated that N. jatamansi samples from Sichuan and Tibet shared similar elemental patterns. The altitude did not statistically influence the elemental patterns of N. jatamansi samples, while the K, P, Ba and Cd showed meaningful decreases. The high Ba contents in all samples suggested the potential toxicity of heavy metal to patients. Conclusion:: The inorganic element quantification of N. jatamansi is useful in the genuine regional drug identification, quality control and biosafety evaluations.

Interactive effects of elevation and land use on soil bacterial communities in the Tibetan Plateau

The Tibetan Plateau of China is uniquely vulnerable to the global climate change and anthropogenic disturbances. As soil bacteria exert a considerable influence on the ecosystem function, understanding their response to different climates and land-use types is important. Here, we characterized the bacterial community composition and diversity across three major ecosystems (cropland, forest, and grassland) in the Sygera Mountains of Tibet, along a typical elevational gradient (3 300–4 600 m). The abundance of taxa that preferentially inhabit neutral or weak alkaline soil environments (such as Actinobacteria, Thermoleophilia, and some non-acidophilus Acidobacteria) was significantly greater in the cropland than in the forest and grassland. Furthermore, the diversity of soil bacterial communities was also significantly greater in the cropland than in the forest and grassland. We observed a unimodal distribution of bacterial species diversity along the elevation gradient. The dominant phyla Acidobacteria and Proteobacteria exhibited consistent elevational distribution patterns that mirrored the abundance of their most abundant classes, while different patterns were observed for Acidobacteria and Proteobacteria at the class level. Soil pH was the primary edaphic property that regulated bacterial community composition across the different land-use types. Additionally, soil pH was the main factor distinguishing bacterial communities in managed soils (i.e., cropland) from the communities in the natural environments (i.e., forest and grassland). In conclusion, land use (particularly anthropogenic disturbances such as cropping) largely controlled soil environment, played a major role in driving bacterial community composition and distribution, and also surpassed climate in affecting bacterial community distribution.

Direct and indirect influences of long-term fertilization on microbial carbon and nitrogen cycles in an alpine grassland

Beginning in the twentieth century, atmospheric deposition of N and P greatly increased in terrestrial ecosystems, including alpine grasslands. These inputs have profoundly affected soil microbial C and N cycles. Changes in the microbial environment are directly caused by changes in soil N and P availability and also indirectly through changes in vegetation in response to increased fertilization. The mechanisms involved in both the direct and indirect changes are not mutually exclusive and are poorly understood. Therefore, we investigated the responses of vegetation and soil microbes to a 9-year fertilization (N and P) experiment in an alpine grassland in the Qinghai–Tibetan Plateau in China. We found that N addition altered soil microbial community composition and processes regardless of P addition. To maintain stoichiometric homeostasis, soil microbes adjusted metabolic processes in response to changes in nutrient availability. High N availability enhanced microbial investment in C acquisition as indicated by β-1,4-Glucosidase activity. The abundance of microbial taxa that degrade labile C also increased. High N inputs also induced a proliferation of denitrifiers and increased the gaseous N loss potential. Partial least squares path modelling indicated that soil parameters (e.g., soil organic C and total N) and changes in the plant community played a key role in shaping soil microbial community structure and C and N cycling. Our results suggest that vegetation and stoichiometric differences between resource availability and soil microbial nutrient requirements collectively regulate the responses of soil microbial processes to N enrichment, which provides novel experimental insights into the mechanisms underlying the effects of nutrient inputs on microbial C and N cycles. Ultimately, our findings highlight the importance of plant traits in regulating microbial nutrient cycles, further promoting our comprehension about the mechanism of variation in the microbial nutrient cycles in an alpine grassland soils.

First Measurement of Soil Freeze/Thaw Cycles in the Tibetan Plateau Using CYGNSS GNSS-R Data

The process of soil freezing and thawing refers to the alternating phase change of liquid water and solid water in the soil, accompanied by a large amount of latent heat exchange. It plays a vital role in the land water process and is an important indicator of climate change. The Tibetan Plateau in China is known as the “roof of the world”, and it is one of the most prominent physical characteristics is the freezing and thawing process of the soil. For the first time, this paper utilizes the spaceborne GNSS-R mission, i.e., CYGNSS (Cyclone Global Navigation Satellite System), to study the feasibility of monitoring the soil freeze-thaw (FT) cycles on the Tibetan Plateau. In the theoretical analysis part, model simulations show that there are abrupt changes in soil permittivities and surface reflectivities as the soil FT occurs. The CYGNSS reflectivities from January 2018 to January 2020 are compared with the SMAP FT state. The relationship between CYGNSS reflectivity and SMAP soil moisture within this time series is analyzed and compared. The results show that the effect of soil moisture on reflectivity is very small and can be ignored. The periodic oscillation change of CYGNSS reflectivity is almost the same as the changes in SMAP FT data. Freeze-thaw conversion is the main factor affecting CYGNSS reflectivity. The periodical change of CYGNSS reflectivity in the 2 years indicates that it is mainly caused by soil FT cycles. It is feasible to use CYGNSS to monitor the soil FT cycles in the Tibetan Plateau. This research expands the current application field of CYGNSS and opens a new chapter in the study of cryosphere using spaceborne GNSS-R with high spatial-temporal resolution.

Achieving Higher Resolution Lake Area from Remote Sensing Images Through an Unsupervised Deep Learning Super-Resolution Method

Lakes have been identified as an important indicator of climate change and a finer lake area can better reflect the changes. In this paper, we propose an effective unsupervised deep gradient network (UDGN) to generate a higher resolution lake area from remote sensing images. By exploiting the power of deep learning, UDGN models the internal recurrence of information inside the single image and its corresponding gradient map to generate images with higher spatial resolution. The gradient map is derived from the input image to provide important geographical information. Since the training samples are only extracted from the input image, UDGN can adapt to different settings per image. Based on the superior adaptability of the UDGN model, two strategies are proposed for super-resolution (SR) mapping of lakes from multispectral remote sensing images. Finally, Landsat 8 and MODIS (moderate-resolution imaging spectroradiometer) images from two study areas on the Tibetan Plateau in China were used to evaluate the performance of UDGN. Compared with four unsupervised SR methods, UDGN obtained the best SR results as well as lake extraction results in terms of both quantitative and visual aspects. The experiments prove that our approach provides a promising way to break through the limitations of median-low resolution remote sensing images in lake change monitoring, and ultimately support finer lake applications.

Analysis of microplastics in a remote region of the Tibetan Plateau: Implications for natural environmental response to human activities

Microplastics are one of the most valuable indicators reflecting the effects of human activities on natural environment. This study was conducted in a representative remote region of Tibetan Plateau in China, simultaneously analyzing the abundance, compositions and fate of MPs both in water and soil media. MPs were detected in surface water, sediment and soil with abundances ranging from 66.6 to 733.3 number/m3, 20 to 160 items/kg, and 20 to 110 items/kg, respectively. Fibers were the most frequently observed shape in the surface water and sediment, while the dominant shape in the soil was film. The major polymers of MPs in water and soil samples were polypropylene (PP) and polyethylene (PE). Small MPs were the main components with the <500μm fraction accounting for 94.74%, 88.37% and 88.34% of total MP particles in surface water, sediment and soil, respectively. Correlation analysis was further conducted to identify the sources of MPs from different human activities. The night light index was innovatively used to represent population rather than local residents, considering the large number of tourists in this region. It was found that tourism was the main source of MPs in water bodies, while facility agriculture and previous secondary industry are major contributors to soil MPs. A simplified equation set for MP abundance prediction was also formulated related to different industrial features. This study provides an evidence of noticeable MPs associated with human activities even at remote regions, and advances a feasible tool for MPs prediction according to local economic development. CapsuleThe effect of human activities on natural environment in a remote region was illustrated by evaluating the abundance, compositions and fate of MPs across freshwater and terrestrial environment.