Due to increased levels of human activity, various pollutants are frequently detected on the Tibetan Plateau, where the environment is extremely fragile and sensitive. Therefore, this study investigated the sources, pollution, and ecological risks of soil potentially toxic elements (PTEs) in different landscape areas within the Qaidam Basin in the northeastern part of the Qinghai–Tibet Plateau. The contents of seven PTEs (Cd, Cu, Pb, Zn, As, Cr, and Ni) in 32 topsoil samples (0–2 cm) were analyzed in different regions of the Qaidam Basin. The concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn were 10.4–29.9 mg/kg, 0.08–4.45 mg/kg, 19–66 mg/kg, 8.2–40 mg/kg, 11.7–30.8 mg/kg, 11.1–31.2 mg/kg, and 32–213 mg/kg, respectively. The correlation between Pb and Cd in unpopulated areas was 0.896 (p < 0.01). The correlations among Pb, Cd, and Zn in agricultural areas, among As, Cd, Cr, and Zn in saline lake areas, and among As, Cd, Cr, Cu, Ni, Pb, and Zn in residential areas were all greater than 0.65 (p < 0.05). The principal component analysis results showed that Pb and Cd in unpopulated areas, Pb, Cd, and Zn in agricultural areas, As, Cd, Cr, Zn, and Pb in saline lake areas, and As, Cd, Cr, Cu, Ni, Pb, and Zn in residential areas were affected by human activities (significant factor >0.70). Based on the geological accumulation index and single-factor pollution index results, the maximum Cd values were found to be 4.93 and 45.88, respectively; Cd was thus the most serious PTE pollutant. The comprehensive pollution index of Nemero showed that moderately and severely polluted areas accounted for 18.89% and 18.46% of the total area, respectively. The results of the potential risk index showed that very strong and strong ecological risk points together accounted for 18.8% of the total points. The spatial variations in PTE pollution and the potential ecological risk index had similar patterns; both increased from the unpopulated areas in the northeastern Qaidam Basin to Golmud city in the south-western Qaidam Basin. These results indicate that human activities negatively impacted the soil ecological environment in the Qaidam Basin during the rapid development of the economy and urbanization and that these negative impacts tended to spread to unpopulated areas. Therefore, it is necessary to emphasize the significant impacts of human activities on environmental quality and formulate preventive measures to reduce PTE pollution in the Qinghai–Tibet Plateau.

Urban wetlands, an important part of the urban ecosystem, play an important role in regional carbon cycles and the carbon balance. To analyze the CO₂ source and sink effects of plateau urban wetlands, based on the data measured by an eddy covariance instrument, the temporal and spatial characteristics of CO₂ flux and their influencing factors in the urban wetland of Xining City in the Qinghai Province of China during a warm season (July to September 2020) were studied. The results show that: (1) On the daily scale, the CO₂ flux exhibited an obvious “U”-type variation, characterized by strong uptake in the daytime and weak emission at night, with an average daily flux of −0.05 mg·m⁻²·s⁻¹. The CO₂ uptake peak of the wetland took place at 13:00 (−0.62 mg·m⁻²·s⁻¹), and the emission peak occurred at 23:30 (0.34 mg·m⁻²·s⁻¹); (2) on the monthly scale, the CO₂ flux of the wetland in the study period showed a net uptake each month. The flux increased month by month, and the maximum value occurred in September (−142.82 g·m⁻²·month⁻¹); (3) from a spatial point of view, the river area showed a weak CO₂ uptake (−0.07 ± 0.03 mg·m⁻²·s⁻¹), while the artificial wetland area showed a strong CO₂ uptake (−0.14 ± 0.03 mg·m⁻²·s⁻¹). The former was significantly lower than the latter (p < 0.01); (4) the regression analysis results show that the CO₂ flux was significantly correlated with PAR, VPD, T_soil, and SWC (p < 0.01). The relationships between the flux and PAR, T_soil, and SWC were rectangular hyperbola (y = 0.2304 − 2 × 10⁻³x/(0.9037 + 0.0022x), R² = 0.64), exponential (y = 0.046exp(0.091x), R² = 0.88), and quadratic (y = −0.0041x² + 0.1784x − 1.6946, R² = 0.83), respectively. Under the joint action of various environmental factors, the urban wetland ecosystem in plateau displayed a strong carbon sink function in warm seasons. This study can establish a data scaffold for the accurate estimation of carbon budget of this type of ecosystem.

Soil microbial communities are pivotal in maintaining ecosystem functions, particularly in alpine regions with highly heterogeneous environmental conditions. However, the influence of vegetation type on soil microbial communities in high-elevation areas remains insufficiently understood. This study investigates the dynamics of soil microbial communities across grassland, shrubland, and forest ecosystems on the southern slope of the Qilian Mountains. Soil bacterial and fungal communities were examined using high-throughput 16S rRNA and ITS gene sequencing, and their potential ecological functions were inferred using the FAPROTAX and FUNGuild databases. Analysis of similarity (ANOSIM) based on Bray–Curtis distances revealed significant differences in bacterial and fungal community structures among vegetation types, with forest soils showing greater intra-group variability and more distinct microbial assemblages. Acidobacteriota and Proteobacteria were the dominant bacterial phyla, while Basidiomycota and Ascomycota predominated among fungi. Fungal communities in forest soils were dominated by ectomycorrhizal taxa, closely linked to coniferous forests dominated by Picea crassifolia. Overall, the structure and functional diversity of soil microbial communities were governed by soil physicochemical properties, particularly soil pH, which emerged as a key influencing factor. These findings deepen our understanding of microbial ecological processes in alpine environments and offer valuable insights for effective vegetation management and ecosystem conservation in mountainous regions.

Based on the NPP products of MODIS data, the spatial and temporal distribution characteristics of grassland NPP and its response to climatic factors in the vegetation growing season of the main river valleys in the southern slope of Qilian Mountains from 2000 to 2016 were carried out by correlation analysis and spatial interpolation. The research further provides a scientific basis for the quality evaluation of grassland ecosystems on the southern slope of Qilian Mountain and the rational use of grassland resources along the river. The results show that: (1) With the increasing distance of buffers on both sides of the river, the NPP of grassland in each year shows the characteristics of “single-peak” distribution, which is increased first and then decreased; (2) the NPP of grassland in the main river valley of the southern slope of Qilian Mountain The spatial distribution characteristics show a trend of increasing from northwest to southeast. (3) The spatial distribution of NPP and air temperature in the main river valleys of the southern slope of Qilian Mountains is gradually increasing from northwest to southeast, but the spatial distribution correlation coefficient of NPP and precipitation in the river valley grassland of vegetation growing season basically shows a trendof decreasing from northwest to southeast.

This study, based on stable hydrogen and oxygen isotope observations of multiple water bodies (precipitation, river water, soil water, and groundwater) in the Ami Dongsou alpine arid watershed on the southern slope of the Qilian Mountains during 2023–2024, reveals significant seasonal fluctuations in water isotope characteristics and water source renewal mechanisms. The results show that precipitation and soil water exhibit notable enrichment during the dry season, primarily due to enhanced evaporation causing light isotopes to evaporate and heavy isotopes to accumulate. River water, influenced by both precipitation recharge and evaporation, shows smaller seasonal fluctuations. Groundwater isotopes remain stable, reflecting a slower water source renewal process with minimal seasonal influence. Through quantitative comparisons of the evaporation line’s slope and intercept, this study finds that precipitation is most significantly affected by evaporation, while groundwater is least influenced, showing more stable isotope characteristics. Climate and topography in high-altitude areas significantly regulate water isotope characteristics, especially during the dry season, where evaporation plays a dominant role in the enrichment of precipitation and river water isotopes. This study innovatively establishes an evidence framework for the linkage of multiple water body isotopes, revealing the “seasonal strong fluctuations + differential water body responses + high-altitude regulation” mechanism of water isotopes in alpine arid regions. It provides new data support for water resource management, particularly in aspects such as water source allocation during the dry season, groundwater protection, and evaporation enrichment effect prediction. Future research could expand the sample size and integrate multi-source data and hydrological models to further improve the accuracy of hydrological process predictions, offering more precise support for watershed water resource management and ecological protection.

Understanding how ecohydrological processes shape soil–plant–water interactions across various ecosystem types is vital for elucidating vegetation water-use strategies in cold, arid regions. This study focused on mountain ecosystems along the northeastern margin of the Qinghai–Tibet Plateau. By comprehensively collecting data on soil profiles, soil moisture and salinity characteristics, and plant leaf functional traits, we systematically evaluated the mechanisms by which these factors influence plant water-use efficiency (WUE). Our findings revealed that soil carbon, nitrogen, phosphorus, and moisture were markedly enriched in the surface layer (0–20 cm), with spatial heterogeneity largely controlled by ecosystem type. Patterns of water–salt interactions followed two distinct regimes: either moisture deficit accompanied by salt accumulation or simultaneous supplementation of water and salt, depending strongly on the hydrological and evapotranspiration context. Moreover, under water-limited conditions, WUE was mainly driven by photosynthetic and water-related traits, whereas in environments with ample water and nutrients, nutrient availability and metabolic traits played a dominant role. These results suggest that ecosystem-specific resource environments shape distinct adaptive strategies for plant water use. This study reveals the mechanism by which ecosystem types regulate water WUE through the coordinated effects of soil moisture patterns and plant functional traits. It provides a theoretical basis for understanding vegetation water adaptation strategies and guiding resource management in cold alpine mountain ecosystems.