In this study,we systematically explored the environmental significance of stable isotope characteristics and the controlling factors of precipitation stable isotopes in the source region of the Three Rivers(SRTR),the...In this study,we systematically explored the environmental significance of stable isotope characteristics and the controlling factors of precipitation stable isotopes in the source region of the Three Rivers(SRTR),the transitional zone of the Qinghai-Tibet Plateau in China.A total of 862 precipitation samples were collected from six fixed-point sampling locations between 2019 and 2021 in the SRTR.In June,the values of hydrogen(δD)and oxygen(δ^(18)O)stable isotopes were most enriched.The deuterium-excess(d-excess)in atmospheric precipitation was>0 in the SRTR;however,the maximum value of d-excess occurred in October.Moreover,the slopes of the local meteoric water line(LMWL)for Dari,Zaduo,Maduo,Qumalai,and Tuotuohe sites were lower than those of the global met-eoric water line(GMWL).In contrast,the slope of the LMWL for Zhimenda was higher than that of the GMWL.The altitude effects of oxygen(δ^(18)O)and hydrogen(δD)isotopes of precipitation were 0.70‰/100 m and 5.22‰/100 m,respectively.When the temperature was≤5℃,there was a significant temperature effect on stable oxygen isotope of precipitation(0.24‰/℃,P<0.05).Furthermore,even a minor increase(1%)in the weight of raindrops after falling results in a 0.82%rise in the evaporation enrichment rate ofδ^(18)O.Success-ive precipitation events also had a substantial influence on precipitation in the transitional region of the Qinghai-Tibet Plateau.The res-ults of this study provide a theoretical basis for revealing the impact mechanism of precipitation in the transitional zone of the Qinghai-Tibet Plateau under a warming climate.展开更多
A thorough understanding of the source and infiltration mechanism of soil water is of great significance to the stable supply of regional water resources and the protection of ecological environment.To solve this cruc...A thorough understanding of the source and infiltration mechanism of soil water is of great significance to the stable supply of regional water resources and the protection of ecological environment.To solve this crucial scientific problem,a total of 1980 samples of various water bodies in Qilian Mountains were collected in early,heavy and end ablation period in 2012-2019 to determine the source of soil water with endmember mixing analysis.Double isotope mass balance was used to calculate the relative contribution of piston flow and preferred flow to groundwater.The results of the study show that precipitation dominated the soil water in the study region,and it contributes 78%,89%and 91%of soil water in early,heavy and end ablation periods,respectively.Ground ice meltwater is also an important source of soil water,its contribution was 16%,11%and 7%in early,heavy and end ablation period,respectively.Snowmelt contributed to soil water only during the early(6%)and late(2%)ablation periods.Groundwater is replenished through the combined effects of preferential flow and piston flow.According to double isotope mass balance,the contribution of priority flow to shallow groundwater is 34%,45%and 34%,respectively in early,heavy and end ablation periods.This study identified the sources of soil water and water transport mechanisms in the Qilian Mountains,providing scientific and technological support for water resource conservation and sustainable utilization in cold regions.展开更多
A green pregelatinized glutinous rice flour biological admixture was developed in this paper.The cement hydration process,hydration products,pore structure,and strength of mortar with different quantities of glutinous...A green pregelatinized glutinous rice flour biological admixture was developed in this paper.The cement hydration process,hydration products,pore structure,and strength of mortar with different quantities of glutinous rice flour(GRF),and the macroscopic changes in concrete cracking resistance testing were investigated.Simultaneously,a fast cracking resistance evaluation method based on graphic recognition was proposed.The results indicated that pregelatinized glutinous rice flour(T-GRF)delayed the dissolution rate of anhydrous cement during the induction period,shifting the main exothermic peak of hydration backward.The compressive strength developed slowly in 7-28 d age and returned to normal in 28-56 d.The compressive strength of T-GRF-0.6% modified mortar at 56 d age is less than 10% different from that of control group.The 3.0%T-GRF decreased the total porosity by 3%,and the average pore size decreased from 31.2 to 21.3 nm measured by MIP,indicating that T-GRF could inhibit harmful pores and densify concrete.The crack resistance coefficient of T-GRF modified concrete was obtained by image recognition method,and the GRF could decrease the length,width,and damaged area of cracks in the early age of concrete.展开更多
Understanding the factors that drive variation in species distribution is a central theme of ecological research. Although several studies focused on alpine vegetation, few efforts have been made to identify the envir...Understanding the factors that drive variation in species distribution is a central theme of ecological research. Although several studies focused on alpine vegetation, few efforts have been made to identify the environmental factors that are responsible for the variations in species composition and richness of alpine shrublands using numerical methods. In the present study, we investigated vegetation and associated environmental variables from 45 sample plots in the middle Qilian Mountains of the northwestern China to classify different community types and to elucidate the species- environment relationships. We also estimated the relative contributions of topography and site conditions to spatial distribution patterns of the shrub communities using the variation partitioning. The results showed that four shrub community types were identified and striking differences in fioristic composition were found among them. Species composition greatly depended on elevation, slope, shrub cover, soil pH and organic carbon. The important determinants of species richness were soil bulk density and slope. No significant differences in species richness were detected among the community types. Topography and site conditions had almost equal effects on compositional variation. Nonetheless,a large amount of the variation in species composition remained unexplained.展开更多
Hydrogen and oxygen isotopes in precipitation have been widely used as effective traces to investigate hydrological processes such as evaporation and atmospheric moisture source. This study analyzed δD and δ^(18)O o...Hydrogen and oxygen isotopes in precipitation have been widely used as effective traces to investigate hydrological processes such as evaporation and atmospheric moisture source. This study analyzed δD and δ^(18)O of precipitation in continuous event-based samples at three stations of Pailugou Catchment from November 2012 to December 2013. The δ^(18)O and δD values ranged from-32.32‰ to +3.23‰ and from-254.46‰ to +12.11‰, respectively. Results show that the δ^(18)O displayed a distinct seasonal variation, with enriched values occurring in summer and relatively depleted values in winter, respectively. There was a statistically significant positive correlation between the δ^(18)O and δD values and local surface air temperature at all the three stations. The nearest Global Network of Isotopes in Precipitation(GNIP) station(Zhangye), compared to the Meteoric Water Lines for this study, showed the obvious local evaporation effects with lower intercept and slope. Additionally, d-excess(δD- 8δ^(18)O) parameter in precipitation exhibited an anti-phase seasonal variability with the δ^(18)O. The 96-h back trajectories for each precipitation event using Hybrid Single Particle Lagrangian Integrated Trajectory(HYSPLIT) model indicated a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter.展开更多
基金Under the auspices of the National Science Foundation for Distinguished Young Scholars(No.42425107)the Science and Technology Project of Gansu Province(No.24JRRA168,23ZDKA017)+1 种基金the Key Talent Project in Gansu Province(No.2025RCXM057)National Nature Science Foundation of China(No.42107063)。
文摘In this study,we systematically explored the environmental significance of stable isotope characteristics and the controlling factors of precipitation stable isotopes in the source region of the Three Rivers(SRTR),the transitional zone of the Qinghai-Tibet Plateau in China.A total of 862 precipitation samples were collected from six fixed-point sampling locations between 2019 and 2021 in the SRTR.In June,the values of hydrogen(δD)and oxygen(δ^(18)O)stable isotopes were most enriched.The deuterium-excess(d-excess)in atmospheric precipitation was>0 in the SRTR;however,the maximum value of d-excess occurred in October.Moreover,the slopes of the local meteoric water line(LMWL)for Dari,Zaduo,Maduo,Qumalai,and Tuotuohe sites were lower than those of the global met-eoric water line(GMWL).In contrast,the slope of the LMWL for Zhimenda was higher than that of the GMWL.The altitude effects of oxygen(δ^(18)O)and hydrogen(δD)isotopes of precipitation were 0.70‰/100 m and 5.22‰/100 m,respectively.When the temperature was≤5℃,there was a significant temperature effect on stable oxygen isotope of precipitation(0.24‰/℃,P<0.05).Furthermore,even a minor increase(1%)in the weight of raindrops after falling results in a 0.82%rise in the evaporation enrichment rate ofδ^(18)O.Success-ive precipitation events also had a substantial influence on precipitation in the transitional region of the Qinghai-Tibet Plateau.The res-ults of this study provide a theoretical basis for revealing the impact mechanism of precipitation in the transitional zone of the Qinghai-Tibet Plateau under a warming climate.
基金supported by The National Science Foundation For Distinguished Young Scholars(42425107)Self-financed science and technology projects of Qinghai 906 Engineering Survey and Design Institute Co.Ltd(2024-KJ-04)+2 种基金Gansu Province Young Talent Program(2025QNGR53)Gansu Science and Technology Program(25JRRA537)the Top Talent Project of Gansu province,Chinese Academy of Sciences Young Crossover Team Project(JCTD-2022-18).
文摘A thorough understanding of the source and infiltration mechanism of soil water is of great significance to the stable supply of regional water resources and the protection of ecological environment.To solve this crucial scientific problem,a total of 1980 samples of various water bodies in Qilian Mountains were collected in early,heavy and end ablation period in 2012-2019 to determine the source of soil water with endmember mixing analysis.Double isotope mass balance was used to calculate the relative contribution of piston flow and preferred flow to groundwater.The results of the study show that precipitation dominated the soil water in the study region,and it contributes 78%,89%and 91%of soil water in early,heavy and end ablation periods,respectively.Ground ice meltwater is also an important source of soil water,its contribution was 16%,11%and 7%in early,heavy and end ablation period,respectively.Snowmelt contributed to soil water only during the early(6%)and late(2%)ablation periods.Groundwater is replenished through the combined effects of preferential flow and piston flow.According to double isotope mass balance,the contribution of priority flow to shallow groundwater is 34%,45%and 34%,respectively in early,heavy and end ablation periods.This study identified the sources of soil water and water transport mechanisms in the Qilian Mountains,providing scientific and technological support for water resource conservation and sustainable utilization in cold regions.
基金Funded by Hainan Provincial Natural Science Foundation(No.522QN279)State Key Laboratory of High Performance Civil Engineering Materials(No.2023CEM004)。
文摘A green pregelatinized glutinous rice flour biological admixture was developed in this paper.The cement hydration process,hydration products,pore structure,and strength of mortar with different quantities of glutinous rice flour(GRF),and the macroscopic changes in concrete cracking resistance testing were investigated.Simultaneously,a fast cracking resistance evaluation method based on graphic recognition was proposed.The results indicated that pregelatinized glutinous rice flour(T-GRF)delayed the dissolution rate of anhydrous cement during the induction period,shifting the main exothermic peak of hydration backward.The compressive strength developed slowly in 7-28 d age and returned to normal in 28-56 d.The compressive strength of T-GRF-0.6% modified mortar at 56 d age is less than 10% different from that of control group.The 3.0%T-GRF decreased the total porosity by 3%,and the average pore size decreased from 31.2 to 21.3 nm measured by MIP,indicating that T-GRF could inhibit harmful pores and densify concrete.The crack resistance coefficient of T-GRF modified concrete was obtained by image recognition method,and the GRF could decrease the length,width,and damaged area of cracks in the early age of concrete.
基金supported by the National Natural Science Foundation of China (Grant No. 91025002)
文摘Understanding the factors that drive variation in species distribution is a central theme of ecological research. Although several studies focused on alpine vegetation, few efforts have been made to identify the environmental factors that are responsible for the variations in species composition and richness of alpine shrublands using numerical methods. In the present study, we investigated vegetation and associated environmental variables from 45 sample plots in the middle Qilian Mountains of the northwestern China to classify different community types and to elucidate the species- environment relationships. We also estimated the relative contributions of topography and site conditions to spatial distribution patterns of the shrub communities using the variation partitioning. The results showed that four shrub community types were identified and striking differences in fioristic composition were found among them. Species composition greatly depended on elevation, slope, shrub cover, soil pH and organic carbon. The important determinants of species richness were soil bulk density and slope. No significant differences in species richness were detected among the community types. Topography and site conditions had almost equal effects on compositional variation. Nonetheless,a large amount of the variation in species composition remained unexplained.
基金Under the auspices of National Natural Science Foundation of China(No.41501085,41461003)Postdoctoral Science Foundation of China(No.2013M532094)
文摘Hydrogen and oxygen isotopes in precipitation have been widely used as effective traces to investigate hydrological processes such as evaporation and atmospheric moisture source. This study analyzed δD and δ^(18)O of precipitation in continuous event-based samples at three stations of Pailugou Catchment from November 2012 to December 2013. The δ^(18)O and δD values ranged from-32.32‰ to +3.23‰ and from-254.46‰ to +12.11‰, respectively. Results show that the δ^(18)O displayed a distinct seasonal variation, with enriched values occurring in summer and relatively depleted values in winter, respectively. There was a statistically significant positive correlation between the δ^(18)O and δD values and local surface air temperature at all the three stations. The nearest Global Network of Isotopes in Precipitation(GNIP) station(Zhangye), compared to the Meteoric Water Lines for this study, showed the obvious local evaporation effects with lower intercept and slope. Additionally, d-excess(δD- 8δ^(18)O) parameter in precipitation exhibited an anti-phase seasonal variability with the δ^(18)O. The 96-h back trajectories for each precipitation event using Hybrid Single Particle Lagrangian Integrated Trajectory(HYSPLIT) model indicated a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter.
