Based on the interpretations of three seismic profiles and one wide-angle seismic profile across the Northwest Sub-basin,South China Sea.stratigraphic sequences,deformation characteristics and an extension model for t...Based on the interpretations of three seismic profiles and one wide-angle seismic profile across the Northwest Sub-basin,South China Sea.stratigraphic sequences,deformation characteristics and an extension model for this sub-basin have been worked out.Three tectonic-stratigraphic units are determined.Detailed analyses of extension show that the event occurred mainly during the Paleogene and resulted in the formation of half-grabens or grabens distributed symmetrically around the spreading center.Sediments are characterized by chaotic and discontinuous reflectors,indicating clastic sediments. Farther to the southwest,the sub-basin features mainly continental rifting instead of sea-floor spreading. The rifting would have been controlled by the shape of the massif and developed just along the northern edge of the Zhongsha-Xisha Block,rather than joined the Xisha Trough.After 25 Ma.a southward ridge jump triggered the opening of the Southwest Sub-basin.The NW-directed stress caused by the sea-floor spreading of the Northwest Sub-basin may have prevented the continuous opening of the sub-basin.After that the Northwest Sub-basin experienced thermal cooling and exhibited broad subsidence.The deep crustal structure shown by the velocity model from a wide-angle seismic profile is also symmetrical around the spreading center,which indicates that the Northwest Sub-basin might have opened in a pure shear model.展开更多
The coronavirus disease 2019(COVID-19)outbreak in late 2019 significantly impacted global health.The virus’s rapid spread,with its long incubation period and high infection level,caused substantial disruption to regu...The coronavirus disease 2019(COVID-19)outbreak in late 2019 significantly impacted global health.The virus’s rapid spread,with its long incubation period and high infection level,caused substantial disruption to regular social frameworks,production,and lifestyles^([1]).COVID-19 is primarily transmitted through close contact,long-range contaminants,and airborne routes.展开更多
Soil salinization may affect biodiversity and species composition,leading to changes in the plant community structure.However,few studies have explored the spatial pattern of soil salinization and its effects on shrub...Soil salinization may affect biodiversity and species composition,leading to changes in the plant community structure.However,few studies have explored the spatial pattern of soil salinization and its effects on shrub community structure at the ecosystem scale.Therefore,we conducted a transect sampling of desert shrublands in Northwest China during the growing season(June–September)in 2021.Soil salinization(both the degree and type),shrub community structure(e.g.,shrub density and height),and biodiversity parameters(e.g.,Simpson diversity,Margalf abundance,Shannon-Wiener diversity,and Pielou evenness indices)were used to assess the effects of soil salinization on shrub community structure.The results showed that the primary degree of soil salinization in the study area was light salinization,with the area proportion of 69.8%.Whereas the main type of soil salinization was characterized as sulfate saline soil,also accounting for 69.8%of the total area.Notably,there was a significant reduction in the degree of soil salinization and a shift in the type of soil salinization from chloride saline soil to sulfate saline soil,with an increase in longitude.Regional mean annual precipitation(MAP),mean annual evapotranspiration(MAE),elevation,and slope significantly contributed to soil salinization and its geochemical differentiation.As soil salinization intensified,shrub community structure displayed increased diversity and evenness,as indicated by the increases in the Simpson diversity,Shannon-Wiener diversity,and Pielou evenness indices.Moreover,the succulent stems and leaves of Chenopodiaceae and Tamaricaceae exhibited clear advantages under these conditions.Furthermore,regional climate and topography,such as MAP,MAE,and elevation,had greater effects on the distribution of shrub plants than soil salinization.These results provide a reference for the origin and pattern of soil salinization in drylands and their effects on the community structure of halophyte shrub species.展开更多
Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This st...Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This study aims to assess the survival of antiretroviral therapy (ART) patients initiated under UTT in Northwest region of Cameroon. Methods: This retrospective cohort study included HIV-positive patients initiated in 2016 at 27 purposefully selected sites and followed until 2021. Data was anonymously abstracted from ART registers and patients’ charts. Kaplan-Meier survival estimates and Cox model were used to compare the survival of patients initiated under UTT with those initiated otherwise, using stata version 14.0. Results: In total, 2490 HIV-positive patients (median age 42.7 years, 94.7% adults, and 69.0% female) participated in the study. Of 1389 patients with viral load (VL) test results, 55% were initiated on ART late. The VL suppression rate of patients initiated late and those initiated early were similar. During follow-up, 1020 (40.9%) participants censored. The survival curves of patients initiated early on ART and those initiated late were similar during the first 2.5 years of follow-up but significantly (p Conclusions: This study confirms the expected impact of UTT. Programs only need to close existing implementation gaps along the critical pathways (diagnosis and treatment) of UTT, focusing more on males.展开更多
Rain-on-snow(ROS)events involve rainfall on snow surfaces,and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China(ARNC).In this study,using dail...Rain-on-snow(ROS)events involve rainfall on snow surfaces,and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China(ARNC).In this study,using daily snow depth data and daily meteorological data from 68 meteorological stations provided by the China Meteorological Administration National Meteorological Information Centre,we investigated the spatiotemporal variability of ROS events in the ARNC from 1978 to 2015 and examined the factors affecting these events and possible changes of future ROS events in the ARNC.The results showed that ROS events in the ARNC mainly occurred from October to May of the following year and were largely distributed in the Qilian Mountains,Tianshan Mountains,Ili River Valley,Tacheng Prefecture,and Altay Prefecture,with the Ili River Valley,Tacheng City,and Altay Mountains exhibiting the most occurrences.Based on the intensity of ROS events,the areas with the highest risk of flooding resulting from ROS events in the ARNC were the Tianshan Mountains,Ili River Valley,Tacheng City,and Altay Mountains.The number and intensity of ROS events in the ARNC largely increased from 1978 to 2015,mainly influenced by air temperature and the number of rainfall days.However,due to the snowpack abundance in areas experiencing frequent ROS events in the ARNC,snowpack changes exerted slight impact on ROS events,which is a temporary phenomenon.Furthermore,elevation imposed lesser impact on ROS events in the ARNC than other factors.In the ARNC,the start time of rainfall and the end time of snowpack gradually advanced from the spring of the current year to the winter of the previous year,while the end time of rainfall and the start time of snowpack gradually delayed from autumn to winter.This may lead to more ROS events in winter in the future.These results could provide a sound basis for managing water resources and mitigating related disasters caused by ROS events in the ARNC.展开更多
Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for ...Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for establishing mitigation strategies and sustainable socioeconomic development in arid regions.Shiyang River Basin is an arid watershed in Northwest China with complex characteristics,its ENR and spatial differentiation characteristics in 2020 were investigated in this work based on the Complex Adaptive System(CAS)theory.The results indicated that the mean Ecological Network Resilience Index(ENRI)value for the Shiyang River Basin was 0.390 in 2020,and the mean values in the southern mountainous,middle oasis,and northern desert regions of the basin were 0.598,0.461,and 0.237,respectively,demonstrating evident spatial differences.Additionally,the ENR of the basin exhibited distinct distribution characteristics across different dimension,whereas the trend of the integrated ENR of the basin was consistent with that of elemental,structural,and functional resilience,indicating the constructed three-region ENR model based on the logical relationship of element-structure-function was suitable for evaluation of the ENR in arid inland river watersheds.Furthermore,strategies for enhancing regional ENR were proposed from the perspective of adapting to climate change.展开更多
In the context of changes in global climate and land uses,biodiversity patterns and plant species distributions have been significantly affected.Soil salinization is a growing problem,particularly in the arid areas of...In the context of changes in global climate and land uses,biodiversity patterns and plant species distributions have been significantly affected.Soil salinization is a growing problem,particularly in the arid areas of Northwest China.Halophytes are ideal for restoring soil salinization because of their adaptability to salt stress.In this study,we collected the current and future bioclimatic data released by the WorldClim database,along with soil data from the Harmonized World Soil Database(v1.2)and A Big Earth Data Platform for Three Poles.Using the maximum entropy(MaxEnt)model,the potential suitable habitats of six halophytic plant species(Halostachys caspica(Bieb.)C.A.Mey.,Halogeton glomeratus(Bieb.)C.A.Mey.,Kalidium foliatum(Pall.)Moq.,Halocnemum strobilaceum(Pall.)Bieb.,Salicornia europaea L.,and Suaeda salsa(L.)Pall.)were assessed under the current climate conditions(average for 1970-2000)and future(2050s,2070s,and 2090s)climate scenarios(SSP245 and SSP585,where SSP is the Shared Socio-economic Pathway).The results revealed that all six halophytic plant species exhibited the area under the receiver operating characteristic curve values higher than 0.80 based on the MaxEnt model,indicating the excellent performance of the MaxEnt model.The suitability of the six halophytic plant species significantly varied across regions in the arid areas of Northwest China.Under different future climate change scenarios,the suitable habitat areas for the six halophytic plant species are expected to increase or decrease to varying degrees.As global warming progresses,the suitable habitat areas of K.foliatum,S.salsa,and H.strobilaceum exhibited an increasing trend.In contrast,the suitable habitat areas of H.glomeratus,S.europaea,and H.caspica showed an opposite trend.Furthermore,considering the ongoing global warming trend,the centroids of the suitable habitat areas for various halophytic plant species would migrate to different degrees,and four halophytic plant species,namely,S.salsa,H.strobilaceum,H.glomeratus,and H.capsica,would migrate to higher latitudes.Temperature,precipitation,and soil factors affected the possible distribution ranges of these six halophytic plant species.Among them,precipitation seasonality(coefficient of variation),precipitation of the warmest quarter,mean temperature of the warmest quarter,and exchangeable Na+significantly affected the distribution of halophytic plant species.Our findings are critical to comprehending and predicting the impact of climate change on ecosystems.The findings of this study hold significant theoretical and practical implications for the management of soil salinization and for the utilization,protection,and management of halophytes in the arid areas of Northwest China.展开更多
The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir wit...The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir with strong bottom-water drive in Tarim Basin,Northwest China.Such parameters were analyzed as solubility ratio of CO_(2)in oil,gas and water,interfacial tension,in-situ oil viscosity distribution,remaining oil saturation distribution,and oil compositions.The results show that CO_(2)flooding could control water coning and increase oil production.In the early stage of the injection process,CO_(2)expanded vertically due to gravity differentiation,and extended laterally under the action of strong bottom water in the intermediate and late stages.The CO_(2)got enriched and extended at the oil-water interface,forming a high interfacial tension zone,which inhibited the coning of bottom water to some extent.A miscible region with low interfacial tension formed at the gas injection front,which reduced the in-situ oil viscosity by about 50%.The numerical simulation results show that enhanced oil recovery(EOR)is estimated at 5.72%and the oil exchange ratio of CO_(2)is 0.17 t/t.展开更多
Precipitation plays a crucial role in the water cycle of Northwest China.Obtaining accurate precipitation data is crucial for regional water resource management,hydrological forecasting,flood control and drought relie...Precipitation plays a crucial role in the water cycle of Northwest China.Obtaining accurate precipitation data is crucial for regional water resource management,hydrological forecasting,flood control and drought relief.Currently,the applicability of multi-source precipitation products for long time series in Northwest China has not been thoroughly evaluated.In this study,precipitation data from 183 meteorological stations in Northwest China from 1979 to 2020 were selected to assess the regional applicability of four precipitation products(the fifth generation of European Centre for Medium-Range Weather Forecasts(ECMWF)atmospheric reanalysis of the global climate(ERA5),Global Precipitation Climatology Centre(GPCC),Climatic Research Unit gridded Time Series Version 4.07(CRU TS v4.07,hereafter CRU),and Tropical Rainfall Measuring Mission(TRMM))based on the following statistical indicators:correlation coefficient,root mean square error(RMSE),relative bias(RB),mean absolute error(MAE),probability of detection(POD),false alarm ratio(FAR),and equitable threat score(ETS).The results showed that precipitation in Northwest China was generally high in the east and low in the west,and exhibited an increasing trend from 1979 to 2020.Compared with the station observations,ERA5 showed a larger spatial distribution difference than the other products.The overall overestimation of multi-year average precipitation was approximately 200.00 mm and the degree of overestimation increased with increasing precipitation intensity.The multi-year average precipitation of GPCC and CRU was relatively close to that of station observations.The trend of annual precipitation of TRMM was overestimated in high-altitude regions and the eastern part of Lanzhou with more precipitation.At the monthly scale,GPCC performed well but underestimated precipitation in the Tarim Basin(RB=-4.11%),while ERA5 and TRMM exhibited poor accuracy in high-altitude regions.ERA5 had a large bias(RB≥120.00%)in winter months and a strong dispersion(RMSE≥35.00 mm)in summer months.TRMM showed a relatively low correlation with station observations in winter months(correlation coefficients≤0.70).The capture performance analysis showed that ERA5,GPCC,and TRMM had lower POD and ETS values and higher FAR values in Northwest China as the precipitation intensity increased.ERA5 showed a high capture performance for small precipitation events and a slower decreasing trend of POD as the precipitation intensity increased.GPCC had the lowest FAR values.TRMM was statistically ineffective for predicting the occurrence of daily precipitation events.The findings provide a reference for data users to select appropriate datasets in Northwest China and for data developers to develop new precipitation products in the future.展开更多
Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolutio...Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolution, to identify the predominant geochemical processes taking place along the horizontal groundwater flow path, and to characterize anthropogenic factors affecting the groundwater environment based on previous data. The concentrations of major ions and total dissolved solids (TDS) in the groundwater showed a great variation, with 62.5% of the samples being brackish (TDS ≥ 1 000 mg L^-l). The groundwater system showed a gradual hydro-chemical zonation composed of Na^+ -HCO3^-, Na^+ -Mg^2+ -SO4 ^2 -Cl^-, and Na^+ -Cl^-. The relationships among the dissolved species allowed identification of the origin of solutes and the processes that generated the observed water compositions. The dissolution of halite, dolomite, and 2- gypsum explained, in part, the presence of Na^+, K^+, Cl^-, SO^4 , and Ca^2+, but other processes, such as mixing, Na^+ exchange for Ca^2+ and Mg^2+, and calcite precipitation also contributed to the composition of water. Human activity, in particular large-scale water resources development associated with dramatic population growth in the last 50 years, has led to tremendous changes in the groundwater regime, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Solving these largely anthropogenic problems requires concerted, massive and long-term efforts.展开更多
The deep crustal structure of the Northwest Sub-basin(NWSB)of the South China Sea(SCS)is of great importance for understanding the tectonic nature of the continent-ocean transition(COT)and magmatism in this oceanic ba...The deep crustal structure of the Northwest Sub-basin(NWSB)of the South China Sea(SCS)is of great importance for understanding the tectonic nature of the continent-ocean transition(COT)and magmatism in this oceanic basin.The 2-D wide-angle reflection/refraction seismic profile OBS2006-2 is almost parallel to the extinct spreading ridge(ESR)of the NWSB.In addition to the original data,we added the data of two reprocessed OBS stations,and carried out seismic phase re-picking and travel-time imaging to obtain the crustal velocity structure along this profile.Resolution tests demonstrate that the newly acquired velocity structure is more reliable than the prior interpretation.The depth of the Moho(23.5–11.8 km)and crustal thickness(20.5–6.5 km)systematically changes from continental crust of the Xisha Block to the oceanic crust within the NWSB.The COT zone has a width of^20 km and the depth of the Moho decreases from 15.0 to 11.0 km,corresponding to a^4 km decrease in crustal thickness(6–10 km).A high velocity layer(HVL,7.2–7.4 km s–1)exists at the bottom of the crust at the location where the sharp lateral transition of the continental crust to the oceanic crust occurs.Age dating shows that the Doublepeak Seamount was formed at^23 Ma,after the cessation of the NWSB seafloor spreading(~32–25 Ma).The crust beneath the Double-peak Seamount is oceanic with a thickness of 9 km.We infer that this oceanic crust was formed by magmatic upwelling and decompression melting along a pre-existing zone of weakness.展开更多
Extremely heavy rainfall occurred over both Northwest India and North China in September 2021.The precipitation anomalies were 4.1 and 6.2 times interannual standard deviation over the two regions,respectively,and bro...Extremely heavy rainfall occurred over both Northwest India and North China in September 2021.The precipitation anomalies were 4.1 and 6.2 times interannual standard deviation over the two regions,respectively,and broke the record since the observational data were available,i.e.,1901 for India and 1951 for China.In this month,the Asian uppertropospheric westerly jet was greatly displaced poleward over West Asia,and correspondingly,an anomalous cyclone appeared over India.The anomalous cyclone transported abundant water vapor into Northwest India,leading to the heavy rainfall there.In addition,the Silk Road pattern,a teleconnection pattern of upper-level meridional wind over the Eurasian continent and fueled by the heavy rainfall in Northwest India,contributed to the heavy rainfall in North China.Our study emphasizes the roles of atmospheric teleconnection patterns in concurrent rainfall extremes in the two regions far away from each other,and the occurrence of rainfall extremes during the post-or pre-monsoon period in the northern margins of monsoon regions.展开更多
In Table 3 of the published version,“Parameters fi tted for tree height and DBH growth models of Eq.(6)”,the parameters letter mismatched the corresponding values.Hence,the authors regret that this may lead to mista...In Table 3 of the published version,“Parameters fi tted for tree height and DBH growth models of Eq.(6)”,the parameters letter mismatched the corresponding values.Hence,the authors regret that this may lead to mistakes in the tree height and DBH simulation based on the model Eq.(6).The correct Table 3 with exact parameter values is listed as follow.展开更多
Planting a fast-growing multipurpose Acacia decurrens (AD) tree is one of the climate-smart agricultural practices that have been promoted in Ethiopia, which is widely practiced and an important livelihood strategy in...Planting a fast-growing multipurpose Acacia decurrens (AD) tree is one of the climate-smart agricultural practices that have been promoted in Ethiopia, which is widely practiced and an important livelihood strategy in Awi zone. However, the extent of its adoption varies considerably among households in the study area. This study investigated the determinants of intensity of adoption of AD among 385 randomly selected rural households in Awi Zone. Data were gathered using a cross-sectional household survey. Descriptive statistics and Two-limit Tobit model were employed for data analysis. The result of the study shows that on average the intensity of adoption of AD was 0.43 (43% of the total cropland area), though majority of the farmers (48.8%) belong to low level of adoption. The result of the analysis shows that being male, educational level, access to seedling, experience in growing the tree, extension contact has positive and significant relationship with the intensity of adoption. Age of head of household, land holding size, livestock holding size, soil fertility status, disease emergence and road distance have negative and significant influence on intensity of adoption. These suggest that expanding road infrastructure, education, access to seedling, secure land property right, disease management, and provision of extension services related to the AD can also improve smallholder farmers’ intensity of AD adoption. The generated information provides a picture of the study area’s situation to the attention of policy makers, development practitioners and institutional service providers to formulate a better policy intervention to sustain smallholder farmers’ AD plantation.展开更多
Water resource access in the Nouhao sub-basin, assessed based on the availability of drinking water mobilization facilities, the availability of water for uses and the quality of drinking water, revealed that in 2017 ...Water resource access in the Nouhao sub-basin, assessed based on the availability of drinking water mobilization facilities, the availability of water for uses and the quality of drinking water, revealed that in 2017 the basin was covered by 1249 modern water point, main drinking water sources. On average, the sub-basin shows a ratio of 271 users per drinking water point. Communal level shows some disparity with Bittou recording the highest number of people per drinking water point, i.e., around 537. Water that can be captured in the entire sub-basin meets only 42% of the total water needs from the three mains uses: irrigation, domestic consumption and livestock. The highest demander among these uses is Irrigation with 75% of the need, i.e., approximately 12,859,995 m<sup>3</sup>. Water in 33% drinking sources of this sub basin is of poor quality. Arsenic, one of the quality parameters studied, is found in some communes of the sub-basin. 11% of the water points in Bissiga are arsenic polluted making this commune the most arsenic contaminated location. The vulnerability maps deducted from lack of water for uses;lack of drinking water works and poor water quality shows so, the exposure level of the sub-basin’ communes to some potential risks related to low water resources access.展开更多
Water conservation is one of the most important ecosystem functions.This study uses the InVEST model to examine the water conservation function of the Qilian Mountain National Park(QMNP),an important water supply area...Water conservation is one of the most important ecosystem functions.This study uses the InVEST model to examine the water conservation function of the Qilian Mountain National Park(QMNP),an important water supply area in northwest China.We analyzed the spatiotemporal water conservation patterns of QMNP from 1988 to 2019.It showed that the water conservation capacity in QMNP has increased over the past 32 years,reaching a peak of 6.495×108 m3 in 2019.The area with an increased water conservation capacity is 12 times larger than the area with a reduced capacity.We also examined how climatic,land-use,vegetation coverage,and topographical factors influence water conservation functions.We found that precipitation is the main climatic factor in water conservation.The water conservation function also varies with land-cover type,with forests having the highest capacity,followed by grasslands.Lastly,topographical factors,including altitude and slope,also shape the spatial patterns of water conservation functions in QMNP.展开更多
River flow in the Songwe sub-basin is predicted to alter due to climate change, which would have an impact on aquatic habitats, infrastructure, and people’s way of life. Therefore, the influence of climate change sho...River flow in the Songwe sub-basin is predicted to alter due to climate change, which would have an impact on aquatic habitats, infrastructure, and people’s way of life. Therefore, the influence of climate change should be taken into account when making decisions about the sustainable management of water resources in the sub-basin. This study looked into how river discharge would react to climate change in the future. By contrasting hydrological characteristics simulated under historical climate (1981-2010) with projected climate (2011-2040, 2041-2070, and 2071-2100) under two emission scenarios, the effects of climate change on river flow were evaluated (RCP 4.5 and RCP 8.5). The ensemble average of four CORDEX regional climate models was built to address the issue of uncertainty introduced by the climate models. The SWAT model was force-calibrated using the results from the generated ensemble average for the RCP 4.5 and RCP 8.5 emission scenarios in order to mimic the river flow during past (1981-2010) and future (2011-2100) events. The increase in river flows for the Songwe sub-basin is predicted to be largest during the rainy season by both the RCP 4.5 and RCP 8.5 scenarios. Under RCP 8.5, the abrupt decrease in river flow is anticipated to reach its maximum in March 2037, when the discharge will be 44.84 m<sup>3</sup>/sec, and in March 2027, when the discharge will be 48 m<sup>3</sup>/sec. The extreme surge in river flow will peak, according to the RCA4, in February 2023, in April 2083 under RCP 4.5, and, according to the CCLM4 and RCA4, in November 2027 and November 2046, respectively. The expected decrease and increase in river flow throughout both the dry and wet seasons may have an impact on the management of the sub-water basin’s resources, biodiversity, and hydraulic structures. The right adaptations and mitigation strategies should be adopted in order to lessen the negative consequences of climate change on precipitation, temperature, and river flow in the sub-basin.展开更多
基金supported by the National Basic Research Program(973) of China (No.2007CB41170403)the National Natural Science Foundation of China(No.40806023)the Scientific Research Fund of the SIO,SOA(No.1404-10)
文摘Based on the interpretations of three seismic profiles and one wide-angle seismic profile across the Northwest Sub-basin,South China Sea.stratigraphic sequences,deformation characteristics and an extension model for this sub-basin have been worked out.Three tectonic-stratigraphic units are determined.Detailed analyses of extension show that the event occurred mainly during the Paleogene and resulted in the formation of half-grabens or grabens distributed symmetrically around the spreading center.Sediments are characterized by chaotic and discontinuous reflectors,indicating clastic sediments. Farther to the southwest,the sub-basin features mainly continental rifting instead of sea-floor spreading. The rifting would have been controlled by the shape of the massif and developed just along the northern edge of the Zhongsha-Xisha Block,rather than joined the Xisha Trough.After 25 Ma.a southward ridge jump triggered the opening of the Southwest Sub-basin.The NW-directed stress caused by the sea-floor spreading of the Northwest Sub-basin may have prevented the continuous opening of the sub-basin.After that the Northwest Sub-basin experienced thermal cooling and exhibited broad subsidence.The deep crustal structure shown by the velocity model from a wide-angle seismic profile is also symmetrical around the spreading center,which indicates that the Northwest Sub-basin might have opened in a pure shear model.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.42375177,41975141)the Natural Science Foundation of Gansu(Grant No.23JRRA1079)。
文摘The coronavirus disease 2019(COVID-19)outbreak in late 2019 significantly impacted global health.The virus’s rapid spread,with its long incubation period and high infection level,caused substantial disruption to regular social frameworks,production,and lifestyles^([1]).COVID-19 is primarily transmitted through close contact,long-range contaminants,and airborne routes.
基金financially supported by the National Natural Sciences Foundation of China(42330503,42171068)the Third Xinjiang Scientific Expedition Program(2022xjkk0901)the Tianshan Talent Training Program(2023TSYCLJ0048).
文摘Soil salinization may affect biodiversity and species composition,leading to changes in the plant community structure.However,few studies have explored the spatial pattern of soil salinization and its effects on shrub community structure at the ecosystem scale.Therefore,we conducted a transect sampling of desert shrublands in Northwest China during the growing season(June–September)in 2021.Soil salinization(both the degree and type),shrub community structure(e.g.,shrub density and height),and biodiversity parameters(e.g.,Simpson diversity,Margalf abundance,Shannon-Wiener diversity,and Pielou evenness indices)were used to assess the effects of soil salinization on shrub community structure.The results showed that the primary degree of soil salinization in the study area was light salinization,with the area proportion of 69.8%.Whereas the main type of soil salinization was characterized as sulfate saline soil,also accounting for 69.8%of the total area.Notably,there was a significant reduction in the degree of soil salinization and a shift in the type of soil salinization from chloride saline soil to sulfate saline soil,with an increase in longitude.Regional mean annual precipitation(MAP),mean annual evapotranspiration(MAE),elevation,and slope significantly contributed to soil salinization and its geochemical differentiation.As soil salinization intensified,shrub community structure displayed increased diversity and evenness,as indicated by the increases in the Simpson diversity,Shannon-Wiener diversity,and Pielou evenness indices.Moreover,the succulent stems and leaves of Chenopodiaceae and Tamaricaceae exhibited clear advantages under these conditions.Furthermore,regional climate and topography,such as MAP,MAE,and elevation,had greater effects on the distribution of shrub plants than soil salinization.These results provide a reference for the origin and pattern of soil salinization in drylands and their effects on the community structure of halophyte shrub species.
文摘Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This study aims to assess the survival of antiretroviral therapy (ART) patients initiated under UTT in Northwest region of Cameroon. Methods: This retrospective cohort study included HIV-positive patients initiated in 2016 at 27 purposefully selected sites and followed until 2021. Data was anonymously abstracted from ART registers and patients’ charts. Kaplan-Meier survival estimates and Cox model were used to compare the survival of patients initiated under UTT with those initiated otherwise, using stata version 14.0. Results: In total, 2490 HIV-positive patients (median age 42.7 years, 94.7% adults, and 69.0% female) participated in the study. Of 1389 patients with viral load (VL) test results, 55% were initiated on ART late. The VL suppression rate of patients initiated late and those initiated early were similar. During follow-up, 1020 (40.9%) participants censored. The survival curves of patients initiated early on ART and those initiated late were similar during the first 2.5 years of follow-up but significantly (p Conclusions: This study confirms the expected impact of UTT. Programs only need to close existing implementation gaps along the critical pathways (diagnosis and treatment) of UTT, focusing more on males.
基金funded by the National Natural Science Foundation of China(42171145,42171147)the Gansu Provincial Science and Technology Program(22ZD6FA005)the Key Talent Program of Gansu Province.
文摘Rain-on-snow(ROS)events involve rainfall on snow surfaces,and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China(ARNC).In this study,using daily snow depth data and daily meteorological data from 68 meteorological stations provided by the China Meteorological Administration National Meteorological Information Centre,we investigated the spatiotemporal variability of ROS events in the ARNC from 1978 to 2015 and examined the factors affecting these events and possible changes of future ROS events in the ARNC.The results showed that ROS events in the ARNC mainly occurred from October to May of the following year and were largely distributed in the Qilian Mountains,Tianshan Mountains,Ili River Valley,Tacheng Prefecture,and Altay Prefecture,with the Ili River Valley,Tacheng City,and Altay Mountains exhibiting the most occurrences.Based on the intensity of ROS events,the areas with the highest risk of flooding resulting from ROS events in the ARNC were the Tianshan Mountains,Ili River Valley,Tacheng City,and Altay Mountains.The number and intensity of ROS events in the ARNC largely increased from 1978 to 2015,mainly influenced by air temperature and the number of rainfall days.However,due to the snowpack abundance in areas experiencing frequent ROS events in the ARNC,snowpack changes exerted slight impact on ROS events,which is a temporary phenomenon.Furthermore,elevation imposed lesser impact on ROS events in the ARNC than other factors.In the ARNC,the start time of rainfall and the end time of snowpack gradually advanced from the spring of the current year to the winter of the previous year,while the end time of rainfall and the start time of snowpack gradually delayed from autumn to winter.This may lead to more ROS events in winter in the future.These results could provide a sound basis for managing water resources and mitigating related disasters caused by ROS events in the ARNC.
基金Under the Major Special Science and Technology Project of Gansu Province(No.23ZDKA0004)。
文摘Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for establishing mitigation strategies and sustainable socioeconomic development in arid regions.Shiyang River Basin is an arid watershed in Northwest China with complex characteristics,its ENR and spatial differentiation characteristics in 2020 were investigated in this work based on the Complex Adaptive System(CAS)theory.The results indicated that the mean Ecological Network Resilience Index(ENRI)value for the Shiyang River Basin was 0.390 in 2020,and the mean values in the southern mountainous,middle oasis,and northern desert regions of the basin were 0.598,0.461,and 0.237,respectively,demonstrating evident spatial differences.Additionally,the ENR of the basin exhibited distinct distribution characteristics across different dimension,whereas the trend of the integrated ENR of the basin was consistent with that of elemental,structural,and functional resilience,indicating the constructed three-region ENR model based on the logical relationship of element-structure-function was suitable for evaluation of the ENR in arid inland river watersheds.Furthermore,strategies for enhancing regional ENR were proposed from the perspective of adapting to climate change.
基金supported by the Third Xinjiang Scientific Expedition Program (2022xjkk1205)the Tianshan Talent Training Program (2023TSYCTD0084)+2 种基金the Science and Technology Major Program of Xinjiang Uygur Autonomous Region (2023A01002)the Young Top Talents of Xinjiang Normal University (XJNUQB2022-29)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2020437)
文摘In the context of changes in global climate and land uses,biodiversity patterns and plant species distributions have been significantly affected.Soil salinization is a growing problem,particularly in the arid areas of Northwest China.Halophytes are ideal for restoring soil salinization because of their adaptability to salt stress.In this study,we collected the current and future bioclimatic data released by the WorldClim database,along with soil data from the Harmonized World Soil Database(v1.2)and A Big Earth Data Platform for Three Poles.Using the maximum entropy(MaxEnt)model,the potential suitable habitats of six halophytic plant species(Halostachys caspica(Bieb.)C.A.Mey.,Halogeton glomeratus(Bieb.)C.A.Mey.,Kalidium foliatum(Pall.)Moq.,Halocnemum strobilaceum(Pall.)Bieb.,Salicornia europaea L.,and Suaeda salsa(L.)Pall.)were assessed under the current climate conditions(average for 1970-2000)and future(2050s,2070s,and 2090s)climate scenarios(SSP245 and SSP585,where SSP is the Shared Socio-economic Pathway).The results revealed that all six halophytic plant species exhibited the area under the receiver operating characteristic curve values higher than 0.80 based on the MaxEnt model,indicating the excellent performance of the MaxEnt model.The suitability of the six halophytic plant species significantly varied across regions in the arid areas of Northwest China.Under different future climate change scenarios,the suitable habitat areas for the six halophytic plant species are expected to increase or decrease to varying degrees.As global warming progresses,the suitable habitat areas of K.foliatum,S.salsa,and H.strobilaceum exhibited an increasing trend.In contrast,the suitable habitat areas of H.glomeratus,S.europaea,and H.caspica showed an opposite trend.Furthermore,considering the ongoing global warming trend,the centroids of the suitable habitat areas for various halophytic plant species would migrate to different degrees,and four halophytic plant species,namely,S.salsa,H.strobilaceum,H.glomeratus,and H.capsica,would migrate to higher latitudes.Temperature,precipitation,and soil factors affected the possible distribution ranges of these six halophytic plant species.Among them,precipitation seasonality(coefficient of variation),precipitation of the warmest quarter,mean temperature of the warmest quarter,and exchangeable Na+significantly affected the distribution of halophytic plant species.Our findings are critical to comprehending and predicting the impact of climate change on ecosystems.The findings of this study hold significant theoretical and practical implications for the management of soil salinization and for the utilization,protection,and management of halophytes in the arid areas of Northwest China.
文摘The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir with strong bottom-water drive in Tarim Basin,Northwest China.Such parameters were analyzed as solubility ratio of CO_(2)in oil,gas and water,interfacial tension,in-situ oil viscosity distribution,remaining oil saturation distribution,and oil compositions.The results show that CO_(2)flooding could control water coning and increase oil production.In the early stage of the injection process,CO_(2)expanded vertically due to gravity differentiation,and extended laterally under the action of strong bottom water in the intermediate and late stages.The CO_(2)got enriched and extended at the oil-water interface,forming a high interfacial tension zone,which inhibited the coning of bottom water to some extent.A miscible region with low interfacial tension formed at the gas injection front,which reduced the in-situ oil viscosity by about 50%.The numerical simulation results show that enhanced oil recovery(EOR)is estimated at 5.72%and the oil exchange ratio of CO_(2)is 0.17 t/t.
基金supported by the National Key Research and Development Program of China(2023YFC3206300)the National Natural Science Foundation of China(42477529,42371145,42261026)+2 种基金the China-Pakistan Joint Program of the Chinese Academy of Sciences(046GJHZ2023069MI)the Gansu Provincial Science and Technology Program(22ZD6FA005)the National Cryosphere Desert Data Center(E01Z790201).
文摘Precipitation plays a crucial role in the water cycle of Northwest China.Obtaining accurate precipitation data is crucial for regional water resource management,hydrological forecasting,flood control and drought relief.Currently,the applicability of multi-source precipitation products for long time series in Northwest China has not been thoroughly evaluated.In this study,precipitation data from 183 meteorological stations in Northwest China from 1979 to 2020 were selected to assess the regional applicability of four precipitation products(the fifth generation of European Centre for Medium-Range Weather Forecasts(ECMWF)atmospheric reanalysis of the global climate(ERA5),Global Precipitation Climatology Centre(GPCC),Climatic Research Unit gridded Time Series Version 4.07(CRU TS v4.07,hereafter CRU),and Tropical Rainfall Measuring Mission(TRMM))based on the following statistical indicators:correlation coefficient,root mean square error(RMSE),relative bias(RB),mean absolute error(MAE),probability of detection(POD),false alarm ratio(FAR),and equitable threat score(ETS).The results showed that precipitation in Northwest China was generally high in the east and low in the west,and exhibited an increasing trend from 1979 to 2020.Compared with the station observations,ERA5 showed a larger spatial distribution difference than the other products.The overall overestimation of multi-year average precipitation was approximately 200.00 mm and the degree of overestimation increased with increasing precipitation intensity.The multi-year average precipitation of GPCC and CRU was relatively close to that of station observations.The trend of annual precipitation of TRMM was overestimated in high-altitude regions and the eastern part of Lanzhou with more precipitation.At the monthly scale,GPCC performed well but underestimated precipitation in the Tarim Basin(RB=-4.11%),while ERA5 and TRMM exhibited poor accuracy in high-altitude regions.ERA5 had a large bias(RB≥120.00%)in winter months and a strong dispersion(RMSE≥35.00 mm)in summer months.TRMM showed a relatively low correlation with station observations in winter months(correlation coefficients≤0.70).The capture performance analysis showed that ERA5,GPCC,and TRMM had lower POD and ETS values and higher FAR values in Northwest China as the precipitation intensity increased.ERA5 showed a high capture performance for small precipitation events and a slower decreasing trend of POD as the precipitation intensity increased.GPCC had the lowest FAR values.TRMM was statistically ineffective for predicting the occurrence of daily precipitation events.The findings provide a reference for data users to select appropriate datasets in Northwest China and for data developers to develop new precipitation products in the future.
基金Project supported by the National Natural Science Foundation of China (Nos. 40671010 and 40501012).
文摘Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolution, to identify the predominant geochemical processes taking place along the horizontal groundwater flow path, and to characterize anthropogenic factors affecting the groundwater environment based on previous data. The concentrations of major ions and total dissolved solids (TDS) in the groundwater showed a great variation, with 62.5% of the samples being brackish (TDS ≥ 1 000 mg L^-l). The groundwater system showed a gradual hydro-chemical zonation composed of Na^+ -HCO3^-, Na^+ -Mg^2+ -SO4 ^2 -Cl^-, and Na^+ -Cl^-. The relationships among the dissolved species allowed identification of the origin of solutes and the processes that generated the observed water compositions. The dissolution of halite, dolomite, and 2- gypsum explained, in part, the presence of Na^+, K^+, Cl^-, SO^4 , and Ca^2+, but other processes, such as mixing, Na^+ exchange for Ca^2+ and Mg^2+, and calcite precipitation also contributed to the composition of water. Human activity, in particular large-scale water resources development associated with dramatic population growth in the last 50 years, has led to tremendous changes in the groundwater regime, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Solving these largely anthropogenic problems requires concerted, massive and long-term efforts.
基金supported by the National Natural Science Foundation of China(Grant Nos.41730532,91958212,91858212,41606064)the Major Projects for Talent Research Team Introduction of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.GML2019ZD0204)the Guangdong Natural Science Foundation Research Team Project(Grant No.2017A030312002)。
文摘The deep crustal structure of the Northwest Sub-basin(NWSB)of the South China Sea(SCS)is of great importance for understanding the tectonic nature of the continent-ocean transition(COT)and magmatism in this oceanic basin.The 2-D wide-angle reflection/refraction seismic profile OBS2006-2 is almost parallel to the extinct spreading ridge(ESR)of the NWSB.In addition to the original data,we added the data of two reprocessed OBS stations,and carried out seismic phase re-picking and travel-time imaging to obtain the crustal velocity structure along this profile.Resolution tests demonstrate that the newly acquired velocity structure is more reliable than the prior interpretation.The depth of the Moho(23.5–11.8 km)and crustal thickness(20.5–6.5 km)systematically changes from continental crust of the Xisha Block to the oceanic crust within the NWSB.The COT zone has a width of^20 km and the depth of the Moho decreases from 15.0 to 11.0 km,corresponding to a^4 km decrease in crustal thickness(6–10 km).A high velocity layer(HVL,7.2–7.4 km s–1)exists at the bottom of the crust at the location where the sharp lateral transition of the continental crust to the oceanic crust occurs.Age dating shows that the Doublepeak Seamount was formed at^23 Ma,after the cessation of the NWSB seafloor spreading(~32–25 Ma).The crust beneath the Double-peak Seamount is oceanic with a thickness of 9 km.We infer that this oceanic crust was formed by magmatic upwelling and decompression melting along a pre-existing zone of weakness.
基金supported by the National Natural Science Foundation of China(Grant No.42105064)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0102)China Meteorological Administration program(Grant No.CXFZ2021J030)。
文摘Extremely heavy rainfall occurred over both Northwest India and North China in September 2021.The precipitation anomalies were 4.1 and 6.2 times interannual standard deviation over the two regions,respectively,and broke the record since the observational data were available,i.e.,1901 for India and 1951 for China.In this month,the Asian uppertropospheric westerly jet was greatly displaced poleward over West Asia,and correspondingly,an anomalous cyclone appeared over India.The anomalous cyclone transported abundant water vapor into Northwest India,leading to the heavy rainfall there.In addition,the Silk Road pattern,a teleconnection pattern of upper-level meridional wind over the Eurasian continent and fueled by the heavy rainfall in Northwest India,contributed to the heavy rainfall in North China.Our study emphasizes the roles of atmospheric teleconnection patterns in concurrent rainfall extremes in the two regions far away from each other,and the occurrence of rainfall extremes during the post-or pre-monsoon period in the northern margins of monsoon regions.
文摘In Table 3 of the published version,“Parameters fi tted for tree height and DBH growth models of Eq.(6)”,the parameters letter mismatched the corresponding values.Hence,the authors regret that this may lead to mistakes in the tree height and DBH simulation based on the model Eq.(6).The correct Table 3 with exact parameter values is listed as follow.
文摘Planting a fast-growing multipurpose Acacia decurrens (AD) tree is one of the climate-smart agricultural practices that have been promoted in Ethiopia, which is widely practiced and an important livelihood strategy in Awi zone. However, the extent of its adoption varies considerably among households in the study area. This study investigated the determinants of intensity of adoption of AD among 385 randomly selected rural households in Awi Zone. Data were gathered using a cross-sectional household survey. Descriptive statistics and Two-limit Tobit model were employed for data analysis. The result of the study shows that on average the intensity of adoption of AD was 0.43 (43% of the total cropland area), though majority of the farmers (48.8%) belong to low level of adoption. The result of the analysis shows that being male, educational level, access to seedling, experience in growing the tree, extension contact has positive and significant relationship with the intensity of adoption. Age of head of household, land holding size, livestock holding size, soil fertility status, disease emergence and road distance have negative and significant influence on intensity of adoption. These suggest that expanding road infrastructure, education, access to seedling, secure land property right, disease management, and provision of extension services related to the AD can also improve smallholder farmers’ intensity of AD adoption. The generated information provides a picture of the study area’s situation to the attention of policy makers, development practitioners and institutional service providers to formulate a better policy intervention to sustain smallholder farmers’ AD plantation.
文摘Water resource access in the Nouhao sub-basin, assessed based on the availability of drinking water mobilization facilities, the availability of water for uses and the quality of drinking water, revealed that in 2017 the basin was covered by 1249 modern water point, main drinking water sources. On average, the sub-basin shows a ratio of 271 users per drinking water point. Communal level shows some disparity with Bittou recording the highest number of people per drinking water point, i.e., around 537. Water that can be captured in the entire sub-basin meets only 42% of the total water needs from the three mains uses: irrigation, domestic consumption and livestock. The highest demander among these uses is Irrigation with 75% of the need, i.e., approximately 12,859,995 m<sup>3</sup>. Water in 33% drinking sources of this sub basin is of poor quality. Arsenic, one of the quality parameters studied, is found in some communes of the sub-basin. 11% of the water points in Bissiga are arsenic polluted making this commune the most arsenic contaminated location. The vulnerability maps deducted from lack of water for uses;lack of drinking water works and poor water quality shows so, the exposure level of the sub-basin’ communes to some potential risks related to low water resources access.
基金supported by the National Key Research and Development Program(2019YFC0507402)。
文摘Water conservation is one of the most important ecosystem functions.This study uses the InVEST model to examine the water conservation function of the Qilian Mountain National Park(QMNP),an important water supply area in northwest China.We analyzed the spatiotemporal water conservation patterns of QMNP from 1988 to 2019.It showed that the water conservation capacity in QMNP has increased over the past 32 years,reaching a peak of 6.495×108 m3 in 2019.The area with an increased water conservation capacity is 12 times larger than the area with a reduced capacity.We also examined how climatic,land-use,vegetation coverage,and topographical factors influence water conservation functions.We found that precipitation is the main climatic factor in water conservation.The water conservation function also varies with land-cover type,with forests having the highest capacity,followed by grasslands.Lastly,topographical factors,including altitude and slope,also shape the spatial patterns of water conservation functions in QMNP.
文摘River flow in the Songwe sub-basin is predicted to alter due to climate change, which would have an impact on aquatic habitats, infrastructure, and people’s way of life. Therefore, the influence of climate change should be taken into account when making decisions about the sustainable management of water resources in the sub-basin. This study looked into how river discharge would react to climate change in the future. By contrasting hydrological characteristics simulated under historical climate (1981-2010) with projected climate (2011-2040, 2041-2070, and 2071-2100) under two emission scenarios, the effects of climate change on river flow were evaluated (RCP 4.5 and RCP 8.5). The ensemble average of four CORDEX regional climate models was built to address the issue of uncertainty introduced by the climate models. The SWAT model was force-calibrated using the results from the generated ensemble average for the RCP 4.5 and RCP 8.5 emission scenarios in order to mimic the river flow during past (1981-2010) and future (2011-2100) events. The increase in river flows for the Songwe sub-basin is predicted to be largest during the rainy season by both the RCP 4.5 and RCP 8.5 scenarios. Under RCP 8.5, the abrupt decrease in river flow is anticipated to reach its maximum in March 2037, when the discharge will be 44.84 m<sup>3</sup>/sec, and in March 2027, when the discharge will be 48 m<sup>3</sup>/sec. The extreme surge in river flow will peak, according to the RCA4, in February 2023, in April 2083 under RCP 4.5, and, according to the CCLM4 and RCA4, in November 2027 and November 2046, respectively. The expected decrease and increase in river flow throughout both the dry and wet seasons may have an impact on the management of the sub-water basin’s resources, biodiversity, and hydraulic structures. The right adaptations and mitigation strategies should be adopted in order to lessen the negative consequences of climate change on precipitation, temperature, and river flow in the sub-basin.