Climate change significantly affects the arid/humid processes and patterns in China,directly impacting management decisions related to adaptive agriculture and water resources management,desertification control,and sp...Climate change significantly affects the arid/humid processes and patterns in China,directly impacting management decisions related to adaptive agriculture and water resources management,desertification control,and spatial ecological restoration.However,current studies primarily focus on changes in arid/humid climate variables,lacking quantitative characterization of the dynamic evolution of areal systems and their nonlinear responses.Based on the data of national meteorological stations from 1961 to 2020,we systematically quantified the nonlinear response of arid/humid patterns to climate change.The results revealed that 6.98%of eco-geographical arid/humid regions underwent type shifts over the past six decades,with 4.95%transitioning toward wetter conditions.Humid and semi-arid regions expanded significantly while sub-humid and arid regions contracted significantly.In the late 1990s,trends of the humid and sub-humid region shifted.Humid region contraction in northern China was driven primarily by precipitation decline,whereas the Tibetan Plateau responded to increasing potential evapotranspiration.During the same period,the retreat rate of the arid region slowed,linked to intensified aridification in the west part of northern China and a decelerating wetting trend in northwest China,both primarily driven by precipitation trends.Our study reveals the nonlinear response of the arid/humid patterns under climate change,providing a scientific basis for the improvement of regional climate resilience.展开更多
Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her...Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her children at their home near the Angola border.展开更多
Non-structural carbohydrates(NSCs)are critical for plant drought adaptation,but their environmental drivers under prolonged drought remains unclear.We investigated seasonal NSCs dynamics in the leaf,stem and root of P...Non-structural carbohydrates(NSCs)are critical for plant drought adaptation,but their environmental drivers under prolonged drought remains unclear.We investigated seasonal NSCs dynamics in the leaf,stem and root of Picea crass ifolia(Qinghai spruce)during the growing seasons of2021-2023 under intensifying drought at three altitudes in Qilian Mountains,Northwest China.Our results revealed synchronous seasonal patterns in soluble sugar,starch,and total non-structural carbohydrate within the same year,contrasting with marked altitudinal disparities.As drought progressed(from 2021 to 2023),soluble sugars initially increased(2022)then declined(2023),while starch showed consistent reduction(except leaves).Moreover,the altitude of peak NSCs concentrations shifted from 3200 m in 2021to 2700 m in 2023.In particular,prolonged drought alters the environmental factors affecting NSCs.NSCs demonstrated significant positive correlations with soil temperature during humid 2021,then negatively with air temperature,vapor pressure deficit,and precipitation during 2022's initial drought,whereas under 2023's persistent drought conditions,soil temperature and water content emerged as dominant drivers.Concurrently,the ratio of soluble sugar to starch transitioned from air temperature and precipitation associations(2021-2022)to soil parameter dependence in2023.These findings provide new insights into the seasonal carbon dynamics of Qinghai spruce and the environmental response mechanisms under increasing drought stress,contributing to a better understanding of tree physiological adaptations in drought stress.展开更多
This study investigates climate-and human-induced hydrological changes in the Zavkhan River-Khyargas Lake Basin,a highly sensitive arid and semi-arid region of Central Asia.Using Mann-Kendall,innovative trend analysis...This study investigates climate-and human-induced hydrological changes in the Zavkhan River-Khyargas Lake Basin,a highly sensitive arid and semi-arid region of Central Asia.Using Mann-Kendall,innovative trend analysis,and Sen's slope estimation methods,historical climate trends(1980-2100)were analyzed,while land cover changes represented human impacts.Future projections were simulated using the MIROC model with Shared Socioeconomic Pathways(SSPs)and the Tank model.Results show that during the past 40 years,air temperature significantly increased(Z=3.93^(***)),while precipitation(Z=-1.54^(*))and river flow(Z=-1.73^(*))both declined.The Khyargas Lake water level dropped markedly(Z=-5.57***).Land cover analysis reveals expanded cropland and impervious areas due to human activity.Under the SSP1.26 scenario,which assumes minimal climate change,air temperature is projected to rise by 2.0℃,precipitation by 21.8 mm,and river discharge by 1.61 m^(3)/s between 2000 and 2100.These findings indicate that both global warming and intensified land use have substantially altered hydrological and climatic processes in the basin,highlighting the vulnerability of western Mongolia's water resources to combined climatic and anthropogenic influence.展开更多
Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis t...Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.展开更多
Under arid and semi-arid bioclimates,steppes are increasingly threatened by anthropogenic disturbance and climatic variability,which strongly affects ecosystem functioning and subsequently leads to desertification.We ...Under arid and semi-arid bioclimates,steppes are increasingly threatened by anthropogenic disturbance and climatic variability,which strongly affects ecosystem functioning and subsequently leads to desertification.We investigated the morphological and physiological responses of Stipa tenacissima L.across three disturbance levels(undisturbed,slightly disturbed,and highly disturbed)in three Tunisian steppe areas(Kasserine,Sidi Bouzid,and Sfax).Morphological and physiological traits were monitored over one year,together with microclimatic variables.Result showed that disturbance was a strong driver of plant functional dynamics,with significant effects on all traits and strong interactions with site and season.Disturbance reduced photosynthetic activity and water use efficiency,particularly in Sfax,where plants adopted conservative strategies(i.e.,higher leaf dry matter content and reduced leaf area).In contrast,undisturbed populations maintained a stronger coordination between physiological and morphological traits.Seasonal analyses revealed that disturbance amplified physiological stress with limited recovery.Heatmap analyses further showed that disturbance weakened trait coordination and reshaped trade-offs between acquisitive and conservative traits.Partial least squares-path modeling showed that morphology strongly drove physiological performance(path coefficient=0.48).Disturbance(path coefficient=0.41)and tussock cover(path coefficient=0.47)influenced morphology both directly and indirectly through their effects on physiology.In conclusion,S.tenacissima adjusts physiological and morphological traits under disturbance,favoring stress tolerance,while undisturbed sites maintain high physiological efficiency and coordinated trait integration,reflecting a trade-off between survival and performance while overriding local site differences.Disturbance strongly restructures trait networks,drives site-specific adjustments,and modulates the seasonal balance between morphological stability and physiological flexibility.展开更多
This study presents a multi-physical modeling approach to analyze the dynamics of moisture potential and stress-deformation features near deep desiccation cracks in clayey soils under three consecutive years’climate ...This study presents a multi-physical modeling approach to analyze the dynamics of moisture potential and stress-deformation features near deep desiccation cracks in clayey soils under three consecutive years’climate variability in an arid region.A triple research approach of statistical analysis,analytical framework,and numerical modeling was used to investigate the complex thermo-hydro-mechanical behavior of desiccation-cracked soil,incorporating realistic climatic data of Qom,Iran.The results revealed the interplay between stress,strain,and pore water pressure over time,demonstrating that soil experiences significant swelling and shrinkage due to cyclic wetting and drying.The horizontal stress distribution shows compressive stress concentration at crack tips during wetting,transitioning to tensile stresses uniformly across the soil surface during drying paths.Similarly,vertical stress distributions exhibit localized compressive stresses along crack boundaries during wetting and tensile stresses during drying,highlighting the critical stress conditions at crack tips.The model differentiates between microstructural and macrostructural changes in porosity.Annual trends in micro-porosity revealed cyclic-dependent behavior,with significant volumetric changes occurring in the first year,stabilizing with successive cycles.The results also indicated that part of the volumetric changes are irreversible,with volumetric plastic strain increasing exponentially but at a decreasing rate over three years.Principal stress analysis indicates a shift from compressive to tensile stress states around cracks,driven by climate-induced wetting and drying cycles.These findings underscore the critical role of climate variability in shaping cracked soil behavior in arid regions,providing insights into the heterogeneous behavior of cracked soil surfFicial layers.展开更多
Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is es...Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is essential for fire management and designing land restoration programs in arid and semi-arid ecosystems.This study provided a new approach to evaluate the flammability of shrublands and woodlands using flammability indices(FIs)including time to ignition(TI),duration of combustion(DC),and flame height(FH)of plant species and their relative frequencies in the Dalfard Basin of southeastern Iran.The results showed that there was a significant difference in FIs between land covers.Shrublands had higher flammability potential compared with woodlands.Plant moisture content had a negative relationship with TI(P<0.010)and no significant relationship with DC and FH(P>0.050).Artemisia spp.,Astragalus gossypinus Fischer,Amygdalus scoparia Spach,and Cymbopogon jwarancusa(Jones)Schult.had the highest FI.Tree species such as Rhazya stricta Decne.,and Pistacia atlantica Desf.showed greater resistance to fire.Using principal component analysis,the relationship between species and FIs was examined,and TI of wet fuel was the most important FI in relation to species.Structural equation model showed that life form(P<0.001)was the most important flammability driver.Precipitation(P<0.010)and legume species(P<0.010)were significantly related to the flammability in arid land.This study emphasizes the importance of managing high-risk species and using resistant species in vegetation restoration and shows that combining species FIs with their abundance is an effective tool for assessing fire risk and fuel management at the plant community scale.展开更多
Surface water plays an essential role in the ecohydrological cycle,especially in water-scarce regions.Changes in surface water restrict social,economic,and agricultural development.However,the patterns and underlying ...Surface water plays an essential role in the ecohydrological cycle,especially in water-scarce regions.Changes in surface water restrict social,economic,and agricultural development.However,the patterns and underlying causes of surface water changes over varying frequencies in global arid regions remain unclear.Thus,this study investigated the changes in surface water and the underlying causes using the trend analysis and Spearman correlation coefficient on the basis of multi-source remote sensing and climate datasets across global arid regions during 2000–2020.The surface water was divided into temporary surface water(TSW),seasonal surface water(SSW),and permanent surface water(PSW)by calculating the surface water inundation frequency.Considering that surface water may be influenced by precipitation in the upper basins,we analyzed the response of surface water area to climatic factors at the basin scale.The area of all surface water(ASW)increased dramatically in global arid regions from 2000 to 2020,increasing from 61.88×104 to 67.40×104 km^(2);however,this increase was accompanied by a decrease in surface water inundation frequency.TSW increased by 55.46%relative to its area in 2000,with a net change rate of 3284.00 km^(2)/a.Changes in surface water were predominantly observed in the Kyzylkum Desert in Central Asia,the Thar Desert in southwestern Asia,and the deserts in Oceania.Precipitation had a significant effect on SSW and TSW at the basin scale.The correlation between precipitation and SSW area can reach 0.808 in the Indus River Basin of the Thar Desert(P<0.01).The findings provide a more comprehensive understanding of surface water variability in global arid regions,carrying significant practical implications for the scientific management of surface water at different frequencies.展开更多
High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective he...High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.展开更多
Rising temperatures and increased droughts caused by climate change significantly reduce crop yields.Halophytes with different photosynthetic metabolism types have specific mechanisms for resistance to climatic factor...Rising temperatures and increased droughts caused by climate change significantly reduce crop yields.Halophytes with different photosynthetic metabolism types have specific mechanisms for resistance to climatic factors.This study analyzed the morphophysiological,biochemical,and molecular-genetic mechanisms of tolerance and adaptation in halophytes,promising candidates for the restoration of salt affected lands in arid and semi-arid areas.Experiments under drought(D)and elevated temperature(eT),as well as their combined action(eT+D),were performed on Atriplex verrucifera M.Bied.(C_(3)plant)and Climacoptera crassa(M.Bieb.)Botsch.(C_(4)-NAD-ME plant)with different types of photosynthesis.The activity of photosystem I(PSI)and the efficiency of photosystem II(PSII)were measured,along with the expression of genes involved in the light(psaA,psaB,psbA,CAB,Fd1,PGR5,and ndhH)and dark(rbcL,Ppc2,and PPDK)reactions of photosynthesis.The content of key carboxylating enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)and phosphoenolpyruvate carboxylase(PEPC),as well as the photorespiration enzyme glycine decarboxylase(GDC),were assessed.Plant growth and water-salt balance parameters,and activity of enzymes in the malate dehydrogenase(MDH)system nicotinamide adenine dinucleotide(phosphate)(NAD(P))-MDH and NAD(P)-malic enzyme(ME)were also examined.A multivariate analysis of the experimental results revealed that A.verrucifera and C.crassa were both resistant to the effects of these climatic stressors.The tolerance mechanisms of both species were significantly influenced by a high level of photosynthetic plasticity.Nevertheless,differences were observed in the protective mechanisms underlying tolerance.In the C_(3)species,dissipative processes associated with non-photochemical quenching(NPQ)of PSII and MDH system enzymes(malate valves)were activated,particularly under osmotic stress.The negative effects in the C_(3)plants were caused by the combined action of eT+D,which was compensated by an increased expression of rbcL,psaA,CAB,and especially PGR5,i.e.,genes encoding Rubisco large subunit and PSI components:apoproteins A,chlorophyll a/b-associated protein(CAB)of light-harvesting complex,and proton gradient regulation 5(PGR5)protein of the main pathway of cyclic electron transport(CET)around PSI.In C_(4)species,the protective MDH complex was expressed to a lesser extent,but activation of the C_(4)carbon-concentrating mechanism(CCM)and upregulation of PGR5 expression were observed,particularly under the individual action of the factors.Under the combined stress of eT+D,C.crassa exhibited a synergistic effect,where the increase in NPQ level and NAD-ME activity,as well as decrease in NADP-ME activity was less pronounced compared with the effect of singular factors.Comparative physiological,biochemical,and molecular analyses of how C_(3)and C_(4)species response to individual and combined climatic factors provide new insights into sustainable plant adaptation strategies in the face of global climate change.Considering the high nutritional value of these two fodder species,a technological approach could be developed to improve the productivity of salt affected lands.展开更多
Within the context of global climate change and rapid urbanization,increasing urban resilience(UR)is especially important in the arid region of Northwest China(ANC),where fragile ecosystems and an uneven water distrib...Within the context of global climate change and rapid urbanization,increasing urban resilience(UR)is especially important in the arid region of Northwest China(ANC),where fragile ecosystems and an uneven water distribution create significant sustainability challenges.In this study,a coupled UR-water ecosystem services(WESs)framework was developed on the basis of 1-km resolution remote sensing data for the 2000–2020 period obtained from the Landsat series,Defense Meteorological Satellite Program(DMSP)/Operational Linescan System(OLS),and Global Precipitation Measurement(GPM),among other sources.Within the framework,the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model was incorporated to provide a WES indicator system.Moreover,entropy weighting was employed to quantify both UR and WES indicators;the coupling coordination degree(CCD)model was used to measure the coupled relationship between UR and WESs;an extreme gradient boosting(XGBoost)-SHapley Additive exPlanations(SHAP)interpretation approach was adopted to identify key drivers and underlying mechanisms;and Geographically Weighted Regression(GWR)was applied to capture spatial distribution characteristics of major driving factors.The results indicated that UR steadily increased from 4.60×10^(-3) to 10.24×10^(-3),whereas WESs followed an inverted V-shaped trend,with a peak value observed in 2010(11.84×10^(-3)).The CCD remained consistently low(mean:0.0166–0.0246)and exhibited considerable spatial heterogeneity.Notably,the degree of coordination was greater in the oasis and mountain core areas but significantly lower at desert areas.XGBoost-SHAP model analysis revealed six key drivers influencing various states of the CCD between UR and WESs systems.The contributions of these factors could be ranked as follows:water yield(WY;24.30%)>farmland area per capita(FP;21.10%)>gross domestic product(GDP)per capita(GDPC;19.00%)>soil retention(SR;14.90%)>population density(PD;5.42%)>water purification(WP;4.40%).In contrast,in UR system,WP(53.66%)and SR(31.62%)served as the dominant drivers.Moreover,the dominant drivers shifted from a combination of natural and socioeconomic factors in StateⅠ(sustainable high resilience)to primarily socioeconomic factors in StateⅢ(unsustainable low resilience).SR and WP exerted positive moderating effects,whereas socioeconomic factors such as GDPC and PD exerted inhibitory effects on the coordination relationship.This research highlights that UR in the ANC region is limited mainly by water scarcity,weak feedback loops,and spatial variability,emphasizing the need for tailored intervention strategies.展开更多
Land use in arid and semi-arid regions has a substantial effect on climate,environment,and biodiversity,thereby projecting the spatiotemporal changes in land use and the subsequent effects.This study employed the loca...Land use in arid and semi-arid regions has a substantial effect on climate,environment,and biodiversity,thereby projecting the spatiotemporal changes in land use and the subsequent effects.This study employed the locally calibrated Future Land Use Simulation(FLUS)model,which coupled system dynamics with cellular automata and integrated an artificial neural network algorithm and a roulette wheel selection mechanism.We projected future land use(2020–2100)dynamics of Lanzhou,a typical river valley city in Northwest China,under three different Shared Socioeconomic Pathway(SSP)scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5).The simulation results were validated and subsequently reclassified using the International Geosphere Biosphere Programme(IGBP)system to produce a dataset suitable for driving climatic and environmental models.Under the SSP1-2.6 scenario,urban and built-up land expanded consistently,whereas irrigated cropland and pasture as well as grassland contracted continuously.Conversely,the SSP5-8.5 scenario was characterized by a contraction of urban and built-up land,and relative stability of irrigated cropland and pasture as well as grassland.The SSP2-4.5 scenario presented a more complex trade-off,where urban and built-up land and grassland increased first and then decreased,whereas irrigated cropland and pasture followed an opposite trajectory.A significant inverse relationship between urban and built-up land and irrigated cropland and pasture was observed under all scenarios,underscoring the fundamental spatial competition that prevailed in this land-constrained valley city.Furthermore,the negative correlation of grassland with urban and built-up land,coupled with the positive correlation of grassland with irrigated cropland and pasture under both the SSP1-2.6 and SSP5-8.5 scenarios,indicated an evolution from broad confrontation to intricate internal trade-offs within the urban–agricultural–ecological system.This study underscored the critical influence of regional topographic and hydrological constraints on land-use evolution in arid regions,providing guidance for water resource management and ecosystem protection in Lanzhou,with applications for sustainable land-use planning in other arid and semi-arid river valley cities.展开更多
Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influenci...Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.展开更多
Approximately 3.44 billion tons of copper mine tailings(MT)were produced globally in 2018 with an increase of 45%from 2010.Significant efforts are being made to manage these tailings through storage facilities,recycli...Approximately 3.44 billion tons of copper mine tailings(MT)were produced globally in 2018 with an increase of 45%from 2010.Significant efforts are being made to manage these tailings through storage facilities,recycling,and reuse in different industries.Currently,a large portion of tailings are managed through the tailing storage facilities(TSF)where these tailings undergo hydro-thermal-mechanical stresses with seasonal cycles which are not comprehensively understood.This study presents an investigative study to evaluate the performance of control and cement-stabilized copper MT under the influence of seasonal cycles,freeze-thaw(F-T)and wet-dry(W-D)conditions,representing the seasonal variability in the cold and arid regions.The control and cement-stabilized MT samples were subjected to a maximum of 12 F-T and 12 W-D cycles and corresponding micro-and-macro behavior was investigated through scanning electron microscope(SEM),volumetric strain(εvT,wet density(r),moisture content loss,and unconfined compressive strength(UCS)tests.The results indicated the vulnerability of Copper MT to 67%and 75%strength loss reaching residual states with 12 F-T and 8 W-D cycles,respectively.Whereas the stabilized MT retained 39%-55%and 16%-34%strength with F-T and W-D cycles,demonstrating increased durability.This research highlights the impact of seasonal cycles and corresponding strength-deformation characteristics of control and stabilized Copper MT in cold and arid regions.展开更多
Northern China is a prominent “hotspot” for land–atmosphere interactions, with substantial gradients in both moisture and thermal conditions. Previous studies have identified a link between land–atmosphere couplin...Northern China is a prominent “hotspot” for land–atmosphere interactions, with substantial gradients in both moisture and thermal conditions. Previous studies have identified a link between land–atmosphere coupling and the individual roles of each factor, but the synergistic effect of the two factors remains unclear. This study considers the covariation of evapotranspiration and precipitation to assess evapotranspiration–precipitation(ET–P) coupling across northern China,exploring its spatial variations and their linkage to water and heat factors. Our findings reveal a transition from strongly positive coupling in the northwest to weakly negative coupling in the southeast, peaking in spring. These spatial variations are attributable to water(soil moisture) and heat(air temperature), which explain 39% and 25% of the variability,respectively. The aridity index(AI), a water–heat synergy factor, is the dominant factor, explaining 66% of the spatial variation in ET–P coupling. As the AI increases, ET–P coupling shifts from strongly positive to weakly negative, with an AI around 0.7. This shift is determined by a shift in the evapotranspiration–lifting condensation level(LCL) coupling under an AI change. Regions with an AI below 0.7 experience water-limited evapotranspiration, where increased soil moisture enhances evapotranspiration, reduces sensible heat(H), and lowers the LCL, resulting in a negative ET–LCL coupling.Conversely, regions with an AI above 0.7 experience energy-limited evapotranspiration, where the positive ET–LCL coupling reflects a positive H–LCL coupling or a positive impact of the LCL on evapotranspiration. This analysis advances our understanding of the intricate influences of multifactor surface interactions on the spatial variations of land–atmosphere coupling.展开更多
基金National Natural Science Foundation of China,No.42377460。
文摘Climate change significantly affects the arid/humid processes and patterns in China,directly impacting management decisions related to adaptive agriculture and water resources management,desertification control,and spatial ecological restoration.However,current studies primarily focus on changes in arid/humid climate variables,lacking quantitative characterization of the dynamic evolution of areal systems and their nonlinear responses.Based on the data of national meteorological stations from 1961 to 2020,we systematically quantified the nonlinear response of arid/humid patterns to climate change.The results revealed that 6.98%of eco-geographical arid/humid regions underwent type shifts over the past six decades,with 4.95%transitioning toward wetter conditions.Humid and semi-arid regions expanded significantly while sub-humid and arid regions contracted significantly.In the late 1990s,trends of the humid and sub-humid region shifted.Humid region contraction in northern China was driven primarily by precipitation decline,whereas the Tibetan Plateau responded to increasing potential evapotranspiration.During the same period,the retreat rate of the arid region slowed,linked to intensified aridification in the west part of northern China and a decelerating wetting trend in northwest China,both primarily driven by precipitation trends.Our study reveals the nonlinear response of the arid/humid patterns under climate change,providing a scientific basis for the improvement of regional climate resilience.
文摘Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her children at their home near the Angola border.
基金supported by the National Natural Science Foundation of China(No.42277481,42007410,32271667,42207537)。
文摘Non-structural carbohydrates(NSCs)are critical for plant drought adaptation,but their environmental drivers under prolonged drought remains unclear.We investigated seasonal NSCs dynamics in the leaf,stem and root of Picea crass ifolia(Qinghai spruce)during the growing seasons of2021-2023 under intensifying drought at three altitudes in Qilian Mountains,Northwest China.Our results revealed synchronous seasonal patterns in soluble sugar,starch,and total non-structural carbohydrate within the same year,contrasting with marked altitudinal disparities.As drought progressed(from 2021 to 2023),soluble sugars initially increased(2022)then declined(2023),while starch showed consistent reduction(except leaves).Moreover,the altitude of peak NSCs concentrations shifted from 3200 m in 2021to 2700 m in 2023.In particular,prolonged drought alters the environmental factors affecting NSCs.NSCs demonstrated significant positive correlations with soil temperature during humid 2021,then negatively with air temperature,vapor pressure deficit,and precipitation during 2022's initial drought,whereas under 2023's persistent drought conditions,soil temperature and water content emerged as dominant drivers.Concurrently,the ratio of soluble sugar to starch transitioned from air temperature and precipitation associations(2021-2022)to soil parameter dependence in2023.These findings provide new insights into the seasonal carbon dynamics of Qinghai spruce and the environmental response mechanisms under increasing drought stress,contributing to a better understanding of tree physiological adaptations in drought stress.
基金The National University of Mongolia,No.P2024-4814The Mongolian Science and Technology Foundation,No.CHN-2022/274The‘Chey Institute for Advanced Studies’International Scholar Exchange Fellowship for the Academic Year of 2025-2026。
文摘This study investigates climate-and human-induced hydrological changes in the Zavkhan River-Khyargas Lake Basin,a highly sensitive arid and semi-arid region of Central Asia.Using Mann-Kendall,innovative trend analysis,and Sen's slope estimation methods,historical climate trends(1980-2100)were analyzed,while land cover changes represented human impacts.Future projections were simulated using the MIROC model with Shared Socioeconomic Pathways(SSPs)and the Tank model.Results show that during the past 40 years,air temperature significantly increased(Z=3.93^(***)),while precipitation(Z=-1.54^(*))and river flow(Z=-1.73^(*))both declined.The Khyargas Lake water level dropped markedly(Z=-5.57***).Land cover analysis reveals expanded cropland and impervious areas due to human activity.Under the SSP1.26 scenario,which assumes minimal climate change,air temperature is projected to rise by 2.0℃,precipitation by 21.8 mm,and river discharge by 1.61 m^(3)/s between 2000 and 2100.These findings indicate that both global warming and intensified land use have substantially altered hydrological and climatic processes in the basin,highlighting the vulnerability of western Mongolia's water resources to combined climatic and anthropogenic influence.
基金Under the auspices of the General Project of Science and Technology Department of Shaanxi Province(No.2023-JCYB-264)General Program of National Natural Science Foundation of China(No.41801004,42371008,42471012)。
文摘Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.
基金supported by the Tunisian Ministry of Higher Education and Scientific Research,Research General Direction,Excellence Project(21P2ES-D1P3)the International Foundation for Science(IFS)(I1-D-6596-1).
文摘Under arid and semi-arid bioclimates,steppes are increasingly threatened by anthropogenic disturbance and climatic variability,which strongly affects ecosystem functioning and subsequently leads to desertification.We investigated the morphological and physiological responses of Stipa tenacissima L.across three disturbance levels(undisturbed,slightly disturbed,and highly disturbed)in three Tunisian steppe areas(Kasserine,Sidi Bouzid,and Sfax).Morphological and physiological traits were monitored over one year,together with microclimatic variables.Result showed that disturbance was a strong driver of plant functional dynamics,with significant effects on all traits and strong interactions with site and season.Disturbance reduced photosynthetic activity and water use efficiency,particularly in Sfax,where plants adopted conservative strategies(i.e.,higher leaf dry matter content and reduced leaf area).In contrast,undisturbed populations maintained a stronger coordination between physiological and morphological traits.Seasonal analyses revealed that disturbance amplified physiological stress with limited recovery.Heatmap analyses further showed that disturbance weakened trait coordination and reshaped trade-offs between acquisitive and conservative traits.Partial least squares-path modeling showed that morphology strongly drove physiological performance(path coefficient=0.48).Disturbance(path coefficient=0.41)and tussock cover(path coefficient=0.47)influenced morphology both directly and indirectly through their effects on physiology.In conclusion,S.tenacissima adjusts physiological and morphological traits under disturbance,favoring stress tolerance,while undisturbed sites maintain high physiological efficiency and coordinated trait integration,reflecting a trade-off between survival and performance while overriding local site differences.Disturbance strongly restructures trait networks,drives site-specific adjustments,and modulates the seasonal balance between morphological stability and physiological flexibility.
基金support provided by the Research Grant Office at Sharif University Technology by way of grants G4010902 and QB020105 is gratefully acknowledged.
文摘This study presents a multi-physical modeling approach to analyze the dynamics of moisture potential and stress-deformation features near deep desiccation cracks in clayey soils under three consecutive years’climate variability in an arid region.A triple research approach of statistical analysis,analytical framework,and numerical modeling was used to investigate the complex thermo-hydro-mechanical behavior of desiccation-cracked soil,incorporating realistic climatic data of Qom,Iran.The results revealed the interplay between stress,strain,and pore water pressure over time,demonstrating that soil experiences significant swelling and shrinkage due to cyclic wetting and drying.The horizontal stress distribution shows compressive stress concentration at crack tips during wetting,transitioning to tensile stresses uniformly across the soil surface during drying paths.Similarly,vertical stress distributions exhibit localized compressive stresses along crack boundaries during wetting and tensile stresses during drying,highlighting the critical stress conditions at crack tips.The model differentiates between microstructural and macrostructural changes in porosity.Annual trends in micro-porosity revealed cyclic-dependent behavior,with significant volumetric changes occurring in the first year,stabilizing with successive cycles.The results also indicated that part of the volumetric changes are irreversible,with volumetric plastic strain increasing exponentially but at a decreasing rate over three years.Principal stress analysis indicates a shift from compressive to tensile stress states around cracks,driven by climate-induced wetting and drying cycles.These findings underscore the critical role of climate variability in shaping cracked soil behavior in arid regions,providing insights into the heterogeneous behavior of cracked soil surfFicial layers.
文摘Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is essential for fire management and designing land restoration programs in arid and semi-arid ecosystems.This study provided a new approach to evaluate the flammability of shrublands and woodlands using flammability indices(FIs)including time to ignition(TI),duration of combustion(DC),and flame height(FH)of plant species and their relative frequencies in the Dalfard Basin of southeastern Iran.The results showed that there was a significant difference in FIs between land covers.Shrublands had higher flammability potential compared with woodlands.Plant moisture content had a negative relationship with TI(P<0.010)and no significant relationship with DC and FH(P>0.050).Artemisia spp.,Astragalus gossypinus Fischer,Amygdalus scoparia Spach,and Cymbopogon jwarancusa(Jones)Schult.had the highest FI.Tree species such as Rhazya stricta Decne.,and Pistacia atlantica Desf.showed greater resistance to fire.Using principal component analysis,the relationship between species and FIs was examined,and TI of wet fuel was the most important FI in relation to species.Structural equation model showed that life form(P<0.001)was the most important flammability driver.Precipitation(P<0.010)and legume species(P<0.010)were significantly related to the flammability in arid land.This study emphasizes the importance of managing high-risk species and using resistant species in vegetation restoration and shows that combining species FIs with their abundance is an effective tool for assessing fire risk and fuel management at the plant community scale.
基金supported by the National Key Research and Development Program of China(2023YFC3208701)the Fundamental Research Funds for the Central Universities(B210201035).
文摘Surface water plays an essential role in the ecohydrological cycle,especially in water-scarce regions.Changes in surface water restrict social,economic,and agricultural development.However,the patterns and underlying causes of surface water changes over varying frequencies in global arid regions remain unclear.Thus,this study investigated the changes in surface water and the underlying causes using the trend analysis and Spearman correlation coefficient on the basis of multi-source remote sensing and climate datasets across global arid regions during 2000–2020.The surface water was divided into temporary surface water(TSW),seasonal surface water(SSW),and permanent surface water(PSW)by calculating the surface water inundation frequency.Considering that surface water may be influenced by precipitation in the upper basins,we analyzed the response of surface water area to climatic factors at the basin scale.The area of all surface water(ASW)increased dramatically in global arid regions from 2000 to 2020,increasing from 61.88×104 to 67.40×104 km^(2);however,this increase was accompanied by a decrease in surface water inundation frequency.TSW increased by 55.46%relative to its area in 2000,with a net change rate of 3284.00 km^(2)/a.Changes in surface water were predominantly observed in the Kyzylkum Desert in Central Asia,the Thar Desert in southwestern Asia,and the deserts in Oceania.Precipitation had a significant effect on SSW and TSW at the basin scale.The correlation between precipitation and SSW area can reach 0.808 in the Indus River Basin of the Thar Desert(P<0.01).The findings provide a more comprehensive understanding of surface water variability in global arid regions,carrying significant practical implications for the scientific management of surface water at different frequencies.
基金funded by King Abdullah City for Atomic and Renewable Energy(KACARE),grant number“PC-2020-1”.
文摘High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.
基金supported by the state assignment of Ministry of Science and Higher Education of the Russian Federation(122042700044-6)the Science and Technology Research Partnership for Sustainable Development(SATREPS)project(JPMJSA2001).
文摘Rising temperatures and increased droughts caused by climate change significantly reduce crop yields.Halophytes with different photosynthetic metabolism types have specific mechanisms for resistance to climatic factors.This study analyzed the morphophysiological,biochemical,and molecular-genetic mechanisms of tolerance and adaptation in halophytes,promising candidates for the restoration of salt affected lands in arid and semi-arid areas.Experiments under drought(D)and elevated temperature(eT),as well as their combined action(eT+D),were performed on Atriplex verrucifera M.Bied.(C_(3)plant)and Climacoptera crassa(M.Bieb.)Botsch.(C_(4)-NAD-ME plant)with different types of photosynthesis.The activity of photosystem I(PSI)and the efficiency of photosystem II(PSII)were measured,along with the expression of genes involved in the light(psaA,psaB,psbA,CAB,Fd1,PGR5,and ndhH)and dark(rbcL,Ppc2,and PPDK)reactions of photosynthesis.The content of key carboxylating enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)and phosphoenolpyruvate carboxylase(PEPC),as well as the photorespiration enzyme glycine decarboxylase(GDC),were assessed.Plant growth and water-salt balance parameters,and activity of enzymes in the malate dehydrogenase(MDH)system nicotinamide adenine dinucleotide(phosphate)(NAD(P))-MDH and NAD(P)-malic enzyme(ME)were also examined.A multivariate analysis of the experimental results revealed that A.verrucifera and C.crassa were both resistant to the effects of these climatic stressors.The tolerance mechanisms of both species were significantly influenced by a high level of photosynthetic plasticity.Nevertheless,differences were observed in the protective mechanisms underlying tolerance.In the C_(3)species,dissipative processes associated with non-photochemical quenching(NPQ)of PSII and MDH system enzymes(malate valves)were activated,particularly under osmotic stress.The negative effects in the C_(3)plants were caused by the combined action of eT+D,which was compensated by an increased expression of rbcL,psaA,CAB,and especially PGR5,i.e.,genes encoding Rubisco large subunit and PSI components:apoproteins A,chlorophyll a/b-associated protein(CAB)of light-harvesting complex,and proton gradient regulation 5(PGR5)protein of the main pathway of cyclic electron transport(CET)around PSI.In C_(4)species,the protective MDH complex was expressed to a lesser extent,but activation of the C_(4)carbon-concentrating mechanism(CCM)and upregulation of PGR5 expression were observed,particularly under the individual action of the factors.Under the combined stress of eT+D,C.crassa exhibited a synergistic effect,where the increase in NPQ level and NAD-ME activity,as well as decrease in NADP-ME activity was less pronounced compared with the effect of singular factors.Comparative physiological,biochemical,and molecular analyses of how C_(3)and C_(4)species response to individual and combined climatic factors provide new insights into sustainable plant adaptation strategies in the face of global climate change.Considering the high nutritional value of these two fodder species,a technological approach could be developed to improve the productivity of salt affected lands.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01B109)the Tianchi Doctoral Program of Xinjiang Uygur Autonomous Region(BS2021007).
文摘Within the context of global climate change and rapid urbanization,increasing urban resilience(UR)is especially important in the arid region of Northwest China(ANC),where fragile ecosystems and an uneven water distribution create significant sustainability challenges.In this study,a coupled UR-water ecosystem services(WESs)framework was developed on the basis of 1-km resolution remote sensing data for the 2000–2020 period obtained from the Landsat series,Defense Meteorological Satellite Program(DMSP)/Operational Linescan System(OLS),and Global Precipitation Measurement(GPM),among other sources.Within the framework,the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model was incorporated to provide a WES indicator system.Moreover,entropy weighting was employed to quantify both UR and WES indicators;the coupling coordination degree(CCD)model was used to measure the coupled relationship between UR and WESs;an extreme gradient boosting(XGBoost)-SHapley Additive exPlanations(SHAP)interpretation approach was adopted to identify key drivers and underlying mechanisms;and Geographically Weighted Regression(GWR)was applied to capture spatial distribution characteristics of major driving factors.The results indicated that UR steadily increased from 4.60×10^(-3) to 10.24×10^(-3),whereas WESs followed an inverted V-shaped trend,with a peak value observed in 2010(11.84×10^(-3)).The CCD remained consistently low(mean:0.0166–0.0246)and exhibited considerable spatial heterogeneity.Notably,the degree of coordination was greater in the oasis and mountain core areas but significantly lower at desert areas.XGBoost-SHAP model analysis revealed six key drivers influencing various states of the CCD between UR and WESs systems.The contributions of these factors could be ranked as follows:water yield(WY;24.30%)>farmland area per capita(FP;21.10%)>gross domestic product(GDP)per capita(GDPC;19.00%)>soil retention(SR;14.90%)>population density(PD;5.42%)>water purification(WP;4.40%).In contrast,in UR system,WP(53.66%)and SR(31.62%)served as the dominant drivers.Moreover,the dominant drivers shifted from a combination of natural and socioeconomic factors in StateⅠ(sustainable high resilience)to primarily socioeconomic factors in StateⅢ(unsustainable low resilience).SR and WP exerted positive moderating effects,whereas socioeconomic factors such as GDPC and PD exerted inhibitory effects on the coordination relationship.This research highlights that UR in the ANC region is limited mainly by water scarcity,weak feedback loops,and spatial variability,emphasizing the need for tailored intervention strategies.
基金supported by the Soft Science Special Project of Gansu Basic Research Plan(25JRZA206)the Longyuan Youth Talent Project of Gansu Province(ZHU Rong)+1 种基金the Innovation Development Special Project of China Meteorological Administration(CXFZ2025J036)the Program of the State Key Laboratory of Cryospheric Science and Frozen Soil Engineering,Chinese Academy of Sciences(CSFSE-KF-2402).
文摘Land use in arid and semi-arid regions has a substantial effect on climate,environment,and biodiversity,thereby projecting the spatiotemporal changes in land use and the subsequent effects.This study employed the locally calibrated Future Land Use Simulation(FLUS)model,which coupled system dynamics with cellular automata and integrated an artificial neural network algorithm and a roulette wheel selection mechanism.We projected future land use(2020–2100)dynamics of Lanzhou,a typical river valley city in Northwest China,under three different Shared Socioeconomic Pathway(SSP)scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5).The simulation results were validated and subsequently reclassified using the International Geosphere Biosphere Programme(IGBP)system to produce a dataset suitable for driving climatic and environmental models.Under the SSP1-2.6 scenario,urban and built-up land expanded consistently,whereas irrigated cropland and pasture as well as grassland contracted continuously.Conversely,the SSP5-8.5 scenario was characterized by a contraction of urban and built-up land,and relative stability of irrigated cropland and pasture as well as grassland.The SSP2-4.5 scenario presented a more complex trade-off,where urban and built-up land and grassland increased first and then decreased,whereas irrigated cropland and pasture followed an opposite trajectory.A significant inverse relationship between urban and built-up land and irrigated cropland and pasture was observed under all scenarios,underscoring the fundamental spatial competition that prevailed in this land-constrained valley city.Furthermore,the negative correlation of grassland with urban and built-up land,coupled with the positive correlation of grassland with irrigated cropland and pasture under both the SSP1-2.6 and SSP5-8.5 scenarios,indicated an evolution from broad confrontation to intricate internal trade-offs within the urban–agricultural–ecological system.This study underscored the critical influence of regional topographic and hydrological constraints on land-use evolution in arid regions,providing guidance for water resource management and ecosystem protection in Lanzhou,with applications for sustainable land-use planning in other arid and semi-arid river valley cities.
基金supported by the Natural Science Foundation of Henan Province(252300421290)the National Natural Science Foundation of China(41771438)+1 种基金the Program for Innovative Research Team(in Science and Technology)of Henan University(22IRTSTHN010)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(HNYJS2020JD14).
文摘Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.
基金the W.M.Keck Center for Nano-Scale Imaging in the Department of Chemistry and Biochemistry at the University of Arizona(Grant No.RRID:SCR_022884),with funding from the W.M.Keck Foundation Grant.
文摘Approximately 3.44 billion tons of copper mine tailings(MT)were produced globally in 2018 with an increase of 45%from 2010.Significant efforts are being made to manage these tailings through storage facilities,recycling,and reuse in different industries.Currently,a large portion of tailings are managed through the tailing storage facilities(TSF)where these tailings undergo hydro-thermal-mechanical stresses with seasonal cycles which are not comprehensively understood.This study presents an investigative study to evaluate the performance of control and cement-stabilized copper MT under the influence of seasonal cycles,freeze-thaw(F-T)and wet-dry(W-D)conditions,representing the seasonal variability in the cold and arid regions.The control and cement-stabilized MT samples were subjected to a maximum of 12 F-T and 12 W-D cycles and corresponding micro-and-macro behavior was investigated through scanning electron microscope(SEM),volumetric strain(εvT,wet density(r),moisture content loss,and unconfined compressive strength(UCS)tests.The results indicated the vulnerability of Copper MT to 67%and 75%strength loss reaching residual states with 12 F-T and 8 W-D cycles,respectively.Whereas the stabilized MT retained 39%-55%and 16%-34%strength with F-T and W-D cycles,demonstrating increased durability.This research highlights the impact of seasonal cycles and corresponding strength-deformation characteristics of control and stabilized Copper MT in cold and arid regions.
基金jointly supported by the National Science Foundation of China (Grant No.42230611)the Meteorological Joint Fund (Grant No.U2142208)+2 种基金the Second Tibetan Plateau Scientific Expedition and Research (STEP) program (grant no.2019QZKK0102)the National Science Foundation of China (Grant No.42005071)the Gansu Province Key Talent Project (Grant No.2023RCXM37)。
文摘Northern China is a prominent “hotspot” for land–atmosphere interactions, with substantial gradients in both moisture and thermal conditions. Previous studies have identified a link between land–atmosphere coupling and the individual roles of each factor, but the synergistic effect of the two factors remains unclear. This study considers the covariation of evapotranspiration and precipitation to assess evapotranspiration–precipitation(ET–P) coupling across northern China,exploring its spatial variations and their linkage to water and heat factors. Our findings reveal a transition from strongly positive coupling in the northwest to weakly negative coupling in the southeast, peaking in spring. These spatial variations are attributable to water(soil moisture) and heat(air temperature), which explain 39% and 25% of the variability,respectively. The aridity index(AI), a water–heat synergy factor, is the dominant factor, explaining 66% of the spatial variation in ET–P coupling. As the AI increases, ET–P coupling shifts from strongly positive to weakly negative, with an AI around 0.7. This shift is determined by a shift in the evapotranspiration–lifting condensation level(LCL) coupling under an AI change. Regions with an AI below 0.7 experience water-limited evapotranspiration, where increased soil moisture enhances evapotranspiration, reduces sensible heat(H), and lowers the LCL, resulting in a negative ET–LCL coupling.Conversely, regions with an AI above 0.7 experience energy-limited evapotranspiration, where the positive ET–LCL coupling reflects a positive H–LCL coupling or a positive impact of the LCL on evapotranspiration. This analysis advances our understanding of the intricate influences of multifactor surface interactions on the spatial variations of land–atmosphere coupling.
