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Different canopy resistance (rc) parameterization has been used in land surface models to simulate actual evapotranspiration (ETc) and soil hydraulic variable for crop fields. However, the influence of rc parameterization on evapotranspiration (ET) partitioning and soil water dynamics has not been fully investigated with consideration of the coupled soil water and vapor physics. This study investigated the influential mechanisms of five rc methods (viz., Jarvis, Katerji-Perrier, Massman, Kelliher-Leuning, and Farias) on ET partitioning and soil water contents in an irrigated maize field under a semiarid climate through a soil water and vapor transfer model. The Jarvis method presented the best ET results (R2 = 0.86 and RMSE = 0.71 mm·d-1). Different rc parameterization mainly altered the simulated amount of soil water contents, while not changed the response of soil water dynamics to irrigation events. By the integrated analysis of the ET partitioning and root-zone water budget, different rc methods varied in the choice of the optimum irrigation water use strategies. This study identified the direct and indirect impacts of rc on the ET partitioning and emphasizes the necessity of both the ET partitioning and water supply sources in the decision-making for irrigation water management in semiarid regions. [ABSTRACT FROM AUTHOR]

Northwest China is much more sensitive to climate warming, and the climate has varied rapidly from warm and drought to warm and humid conditions. In addition, due to the complex terrain of Northwest China, the methods and parameterization schemes of different CMIP6 models, these models are mostly applied to arid areas in Northwest China or Central Asia, lacking climate data for plateau areas and eastern Lanzhou, specifically in filtering CMIP6 models and evaluating applicable models. In this paper, 34 CMIP6 climate models are used to evaluate and forecast future trends in Northwest China under the SSP126, SSP245 and SSP585 scenarios in the short, medium and long term. CMIP6 models of temperature and precipitation are identified by applying the interannual variability skill score (IVS) between CN05.1 datasets and historical CMIP6 models, which are suitable for Northwest China. Then, we assess the characteristics, warming and wetting deviations, and uncertainties in the prediction of climatic change according to CMIP6 models over Northwest China. The results show that CMIP6 models in precipitation and temperature applicable to Northwest China are AWI‐CM‐1‐1‐MR, BCC‐CSM2‐MR, FGOALS‐g3, INM‐CM4‐8, INM‐CM5‐0 and MRI‐ESM2‐0. The multi‐model ensemble mean (MMEM) has better capability than individual CMIP6 models in precipitation and temperature prediction. Spatiotemporal climatic change over Northwest China shows overall warming and wetting trends. The IVS provides the ability to estimate CMIP6 model simulation performance both temporally and spatially. The temperature simulation is quite good in the Tarim Basin and Hexi Corridor region, and the precipitation simulation is quite good in the plateau region, Altai Mountains, Tianshan Mountains and Hexi Corridor region. Cold and wet deviations occur in Northwest China due to the topography and few stations, which are common reasons. The main sources of uncertainties in temperature prediction during this century are model uncertainty (before the 2090s) and scenario variability (after the 2090s), and model uncertainty in precipitation for CMIP6 becomes the main source of uncertainty. [ABSTRACT FROM AUTHOR]

Soil contamination of heavy metals in urban greenspaces can exert detrimental impacts on ecological biodiversity and the health of inhabitants through cross-media migration-induced risks. Here, a total of 72 topsoil samples were collected from greenspaces in the popular tourist city of Tianshui, ranging from areas with parks, residential, road, industrial and educational soils. The study aimed to evaluate an integrated source-specific ecological and human health risk assessment of heavy metals. Among the analyzed heavy metals, except Cr (mean), all exceeded the local background values by 1.30–5.67-fold, and Hg, Cd, Pb and As were the metals with large CV values. The Igeo and CF results showed Hg, Cd, As and Pb exhibited significantly high pollution levels and were the primary pollution factors. The mean PLI values indicated moderate pollution in educational (2.21), industrial (2.07), and road (2.02) soils but slight pollution in park (1.84) and residential (1.39) greenspaces. The Igeo, CF, and PLI results also revealing that these heavy metals are more likely to be affected by human activity. Four primary source factors were identified based on PMF model: coal combustion (25.57%), agricultural sources (14.49%), atmospheric deposition (20.44%) and mixed sources (39.50%). In terms of ecological risk, the mean IRI values showed considerable risks in educational soils (287.52) and moderate risks in road (215.09), park (151.27) and residential (136.71) soils. And the contribution ratio of atmospheric deposition for park, residential, road, industrial and educational greenspaces were 57.72%, 65.41%, 67.69%, 59.60% and 75.76%, respectively. In terms of human health risk, the HI (below 1) and CR (below 1.00E−04) for adults from soils of all land use types was negligible. However, children have more significant non-carcinogenic and carcinogenic hazards especially in residential soils, the HI (above 1) and CR (above 1.00E−04) revealed the significance of regarding legacy As contamination from coal combustion when formulating risk mitigation strategies in this area. The proposed method for source and risk identification makes the multifaceted concerns of pollution and the different relevant risks into a concrete decision-making process, providing robust support for soil contamination control. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Objective] The resilience of urban network structures is a crucial guarantee for the recovery and stability of urban spatial organization. Current research predominantly employs individual flows and focuses on developed regions, and there is relatively little research that combines multidimensional factor flows while also focusing on the resilience of network structures in underdeveloped regions. Therefore, this study took the underdeveloped Northwest China as the research object and explored its network structural resilience based on multidimensional factor flow, in order to fill the gap of related research and enrich the empirical analysis of network resilience from the perspective of multidimensional factor flow. [Methods] This study focused on 51 prefecture-level administrative units in Northwest China for the year 2022. It investigated the structural characteristics of urban networks from three perspectives: economic, transportation, and information, quantitatively measured their hierarchy, matching, transmission, and agglomeration, and examined the structural resilience of Northwest China’s urban networks under various disruption scenarios by using the method of computer simulation and proposed optimization strategies from different perspectives. [Results] (1) The economic, transportation, and information networks across the 51 prefecture-level administrative units in Northwest China are generally distributed in a pattern of dense in the east and sparse in the west, showing core-periphery characteristics, but there are significant differences in the structure of the three types of networks. The economic network density is low and the stickiness between the core nodes is large, showing the characteristics of coexistence of “strong assisting weak” and “strong alliances”, with multi-group pattern and fragmented development trend. The traffic network is more closely linked, with stronger inertia in intercity links, showing a “small world” effect, a spindle-shaped pattern, and a turbulent development trend. The information network has wide coverage and strong permeability, showing coordinated characteristics, a strip-like pattern, and a turbulent development trend. (2) The three types of networks differ greatly in terms of hierarchy and matching, and less in terms of transmission and agglomeration. The Matthew effect of the economic network is obvious, characterized by strong homophily at the core and weak heterophily at the periphery; the traffic network tends to experience three-dimensional development, showing local robustness and regional vulnerability; and the information network has highly heterogeneous resilience, showing the characteristics of flattened network structure and diversified connection paths, with a high level of resilience. (3) Deliberate attacks are significantly more damaging to network resilience than random attacks, and a hit on a core node has a greater impact on network operational efficiency than on a vulnerable node. [Conclusion] The problem of uneven regional development is particularly obvious in less developed regions, where the core city has concentrated power but a shorter radius of radiation, and cities on the periphery are not sufficiently motivated to develop. There are both similarities and differences in resilience characteristics between the three types of networks, and network resilience under different attack modes is characterized by phased changes. In order to promote the sustainable development of the region, response policies should be formulated according to regional characteristics.

Abstract Northwest China has undergone notable alterations in climate and vegetation growth in recent decades. Nevertheless, uncertainties persist concerning the response of different vegetation types to climate change and the underlying mechanisms. This study utilized the Normalized Difference Vegetation Index (NDVI) and three sets of meteorological data to investigate the interannual variations in the association between vegetation and climate (specifically precipitation and temperature) from 1982 to 2015. Several conclusions were drawn. (1) RNDVI-GP (relationship between Growing Season NDVI and precipitation) decreased significantly across all vegetation, while RNDVI-GT (relationship between Growing Season NDVI and temperature) showed an insignificant increase. (2) Trends of RNDVI-GP and RNDVI-GT exhibited great variations across various types of vegetation, with forests displaying notable downward trends in both indices. The grassland exhibited a declining trend in RNDVI-GP but an insignificant increase in RNDVI-GT, while no significant temporal changes in RNDVI-GP or RNDVI-GT were observed in the barren land. (3) The fluctuations in RNDVI-GP and RNDVI-GT closely aligned with variations in drought conditions. Specifically, in regions characterized by VPD (vapor pressure deficit) trends less than 0.02 hpa/yr, which are predominantly grasslands, a rise in SWV (soil water volume) tended to cause a reduction in RNDVI-GP but an increase in RNDVI-GT. However, a more negative trend in SWV was associated with a more negative trend in both RNDVI-GP and RNDVI-GT when the VPD trend exceeded 0.02 hPa/yr, primarily in forests. Our results underscore the variability in the relationship between climate change and vegetation across different vegetation types, as well as the role of drought in modulating these associations.

In this study, we have reported spatial and temporal variation in particulate matter (PM), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3) over five provincial capital cities in northwestern China during 2013–2020. Regarding the seasonal variation, all pollutants (except ozone) exhibited the lowest concentration during summer and the highest concentration during winter, which could be attributed to increased anthropogenic activities (like coal burning) and conducive meteorological features. The highest monthly mean concentrations were primarily observed during December-February, whereas ozone exhibited the highest concentration during April-August, with different cities experiencing the highest concentration during different seasons. Regarding the diurnal variation exhibited by the pollutants, the lowest concentration of pollutants (except O3) was observed during the late afternoon (17:00–18:00) period. Ozone posed the urban site diurnal variation characteristic (peak during afternoon hour) over all sites. Urumqi had the highest PM2.5/PM10 ratio during November-March and the lowest ratio during April-October. Compared to the WHO revised guideline, the annual mean PM2.5 concentration was about 8–12 times higher, whereas the annual PM10 concentration was exceeded by a factor of up to 7. Most pollutants exhibited reduced concentration during the spring festival period. Analysis using HYSPLIT back trajectories indicated that the air masses affecting the five sites primarily originated from the northwestern area of China, although the impact of long-range pollution transport from remote regions should not be overlooked. [ABSTRACT FROM AUTHOR]

The over-exploitation of groundwater and the deterioration of its quality have heightened the importance of non-traditional water resources, such as mine water. The study of the water's chemical characteristics and the formation mechanism of high-salinity mine water in semi-arid regions holds significant importance for zero discharge and the resource utilization of mine water in Northwest China. In this study, a total of 38 groundwater and mine water samples were collected to examine the hydrogeochemical characteristics of high-salinity mine water using Piper diagrams and Gibbs diagrams, as well as isotope analyses and ion ratio coefficients. Additionally, the corresponding mine water treatment recommendations were put forward. The results show that the TDS content of groundwater increases with hydrographic depth. The average TDS concentration of Quaternary, Luohe, and Anding groundwater is 336.87, 308.67, and 556.29 mg/L, respectively. However, the TDS concentration of Zhiluo groundwater and mine water is 2768.57 and 3826.40 mg/L, respectively, which belong to high-salinity water. The Quaternary, Luohe, and Anding groundwater hydrochemical type is predominantly HCO3-Ca type, and the Zhiluo groundwater and mine water hydrochemical type is predominantly the SO4-Na type. Furthermore, there is minimal difference observed in δD and δ18O values among these waters. It can be inferred that the Zhiluo Formation in groundwater serves as the primary source of mine water supply, primarily influenced by the processes of concentration caused by evaporation. The high salinity of mine water is closely related to the high salinity of Zhiluo groundwater. The high salinity of groundwater has evolved gradually under the control of the concentration caused by evaporation and rock-weathering processes. The dissolution of salt rock, gypsum, along with other minerals, serves as the material basis for high-salinity groundwater formation. In addition, the evolution of major ions is also affected by cation exchange. The TDS concentration of mine water ranges from 3435.4 mg/L to 4414.3 mg/L, and the combined treatment process of nanofiltration and reverse osmosis can be selected to remove the salt. After treatment, mine water can be used for productive, domestic, and ecological demands. [ABSTRACT FROM AUTHOR]

The coordinated development of the water–food–ecology (WFE) nexus is a practical issue that has to be addressed urgently for northwest China's (WTL) sustainable development. Optimizing the linkage relationship and accomplishing the rational distribution of resources from the perspective of the supply and demand for ecosystem services (ESSD) are imperative. Thus, in this study, a numerical indicator system for ESSD from the perspective of the WFE nexus was constructed with the incorporation of the water and carbon footprint. Based on this premise, the ecological management zoning method was enhanced by integrating supply and demand risks, and optimization suggestions were proposed for various zones. The results showed that (1) carbon sequestration (CS), food production (FP), and water yield (WY) supply and demand significantly increased between 2000 and 2021. High ESSDs were concentrated in the west side of northwest China. Maize, wheat, cotton, vegetables, and garden fruits had a higher demand for ecosystem services (ESs). (2) The three ESSDs were bound in a synergistic relationship. The synergy between supply exhibited significant spatial heterogeneity, while the synergies between demand showed similar distribution patterns. (3) Regarding quantity matching, the supply for FP and CS surpassed demand, while the WY supply could not meet the demand. The three ESs' supply and demand deficits rose. Ecological supply–demand ratio (ESDR) regional differentiation for the three ESs was apparent. Regarding spatial matching, FP and CS concentrated on low supply–low demand, while WY focused on high supply–high demand. FP risk was concentrated in Qaidam Basin, whereas WY risk was mostly in Hexi inland river basin (HX), the Yellow River Basin area (HH), and both sides of the "Qice line". (4) The ecological management zones were formed by integrating WTL's three dominant weak functional zones, four categorized strategy regions, and four governance models. This study can serve as a scientific benchmark for regional ecological management, which is significant in ensuring northwest China's water, food, and ecological safety. [ABSTRACT FROM AUTHOR]

Northwest China has undergone notable alterations in climate and vegetation growth in recent decades. Nevertheless, uncertainties persist concerning the response of different vegetation types to climate change and the underlying mechanisms. This study utilized the Normalized Difference Vegetation Index (NDVI) and three sets of meteorological data to investigate the interannual variations in the association between vegetation and climate (specifically precipitation and temperature) from 1982 to 2015. Several conclusions were drawn. (1) RNDVI-GP (relationship between Growing Season NDVI and precipitation) decreased significantly across all vegetation, while RNDVI-GT (relationship between Growing Season NDVI and temperature) showed an insignificant increase. (2) Trends of RNDVI-GP and RNDVI-GT exhibited great variations across various types of vegetation, with forests displaying notable downward trends in both indices. The grassland exhibited a declining trend in RNDVI-GP but an insignificant increase in RNDVI-GT, while no significant temporal changes in RNDVI-GP or RNDVI-GT were observed in the barren land. (3) The fluctuations in RNDVI-GP and RNDVI-GT closely aligned with variations in drought conditions. Specifically, in regions characterized by VPD (vapor pressure deficit) trends less than 0.02 hpa/yr, which are predominantly grasslands, a rise in SWV (soil water volume) tended to cause a reduction in RNDVI-GP but an increase in RNDVI-GT. However, a more negative trend in SWV was associated with a more negative trend in both RNDVI-GP and RNDVI-GT when the VPD trend exceeded 0.02 hPa/yr, primarily in forests. Our results underscore the variability in the relationship between climate change and vegetation across different vegetation types, as well as the role of drought in modulating these associations. [ABSTRACT FROM AUTHOR]

The arid and semi-arid region of Northwest China plays a significant role in potato production, yet yields are often hampered by drought due to limited precipitation and irrigation water. The ridge–furrow rainwater-harvesting technology is an efficient and widely used technique to relieve drought impact and improve crop yield by changing the micro-topography to harvest rainwater to meet the water demand of crops. An analysis of precipitation, water demand, and runoff data spanning 30 years guided the selection of suitable rainwater-harvesting methods tailored to meteorological conditions. The results showed that potato water demand exceeded precipitation in the region. The mulching approach performed best in the western arid region with the most significant increase in yield and water use efficiency (WUE) and was suitable for the western semi-arid region and the agro-pastoral ecotone. In the potato dryland farming areas, the water deficit increased from southeast to northwest. Specifically, northern Gansu, northern Ningxia, and midwestern Inner Mongolia experienced a water deficit of over 200 mm, and rainwater harvesting combined with irrigation was recommended. Conversely, regarding deficits below 200 mm in southern Gansu, Ningxia, and central Inner Mongolia, a 1:1 or 2:1 pattern of ridges could be applied, and mulching was needed only in the necessary areas. For the southern Qinghai, Shaanxi, and eastern Inner Mongolia regions, ridge–furrow rainwater harvesting could be replaced by flat potato cropping. In summary, rainwater harvesting addresses water deficits, aiding climate adaptation in Northwest China's arid and semi-arid regions. The implementation of mulching and ridge–furrow technology must be location-specific. [ABSTRACT FROM AUTHOR]

This paper presents a study of ceramics from Northwest China from the Neolithic and Bronze Age (c. 3300–600 BCE), providing insights into variations in human–ceramic interactions over time and space. Based on macroscopic and petrographic analysis of ceramics from 10 sites, this paper shows that there is much more complexity in ceramic technology than previously thought. It identifies a development from a bi‐modal distinction between painted fine ware and rusticated coarse wares shared among communities across Northwest China to strongly localised ceramic traditions with new fabrics, vessel shapes, and decorations, some of them potentially of outside origin, reflecting considerable societal change. [ABSTRACT FROM AUTHOR]

Water conservation is an important ecosystem service, which is crucial to the fragile ecological environment and serious soil erosion in Northwest China. However, water conservation has been affected by climate change and human disturbance, and its future spatial and temporal changes are still unclear. This study employed the Integrated Valuation of Ecosystem Services and Trade‐offs (InVEST) model to assess the water conservation capacity of Northwest China between 1990 and 2020. Subsequently, the Patch‐generating Land Use Simulation (PLUS) model and the NASA Earth Exchange Global Daily Downscaled Projections (NEX‐GDDP‐CMIP6) were integrated to examine changes in water conservation from 2030 to 2050. The water conservation quantity in Northwest China had a fluctuating growth tendency between 1990 and 2020, with an average of 816.61 × 108 m3. The water conservation capacity's regional distribution pattern shows a steady increase from northwest to southeast. Northwest China's forest land had the greatest water conservation capacity between 1990 and 2020, at 66 mm, while the water land had the lowest, at 1.46 mm. The water conservation capacity in the 2030–2050 future scenario is less than that in 2020 when the regional distribution pattern is comparable to 2020. Natural development scenario (ND) in 2030 has the lowest water conservation capacity (13.41 mm) under ssp1‐2.6 precipitation scenario, whereas in 2050, the highest water conservation capacity (17.47 mm) is found in same scenario. The ecological protection scenario (EP) has the greatest water retention capacity (18.15 mm in 2040) and the lowest (14.38 mm in 2050) in the ssp5‐8.5 scenario. Our research can help restore and rebuild Northwest China's natural ecosystem and offer a theoretical foundation for the protection of ecological environment and the rational utilization of water resources in the region. [ABSTRACT FROM AUTHOR]

After the political fragmentation of the "Five Dynasties and Ten Kingdoms" period, the Northern Song consolidated much of the lands under these regional states into a larger polity in a process often described as "reunification." But this "reunification," judged against the domain of the Tang dynasty, was incomplete. The "Sixteen Prefectures" to the northeast were ceded to the Liao, and this became a vexing issue for Song emperors and officials. But the northeast was not the only region once under Tang rule that did not enter the Song domain. In this article, I discuss the area to the northwest of the Song, much of which was eventually governed by the Tangut Xia state. This area, roughly the modern provinces of Ningxia and Gansu, featured prominently in Northern Song political discussions, national geographical treatises, and national and regional maps. By analyzing the treatment of the northwest in these diverse genres of representation, I demonstrate a spectrum in the perceptions of the northwest. It was sometimes seen as little different from areas under Song rule; in other cases, it was treated as "beyond the sphere of civilization" (huawai). Such ambiguity is visualized in many Song cartographers who placed this area between two segments of the Great Wall. For Song emperors and officials, the northwest sat uncomfortably in their imaginations of the world, not easily dismissed and forgotten, yet irrecoverable. [ABSTRACT FROM AUTHOR]

Urban land serves as the medium for urban economic and residential activity. The degree of intensive and efficient use of urban land and the coordinated growth of the economy and society are significantly impacted by utilization efficiency. Northwest China's temperature, geography, water, and soil characteristics make less of the region suited for urban development. Thus, it is imperative to investigate Northwest China's urban land use efficiency (ULUE). This study applies the efficiency loss model to highlight the discrepancy between the optimal and actual values of each input-output variable of the ULUE, and uses the Super-SBM model to compute the ULUE of 39 cities. Additionally, the internal driving elements of the ULUE are examined using the Global Malmquist-Luenberger (GML) index. This study discovered that Northwest China had a low ULUE, with a modest upward trend seen between 2004 and 2018. The overall shape of the region was similar to an 'N' curve, with high efficiency values concentrated in the southeast of the region in 2018. When considering the agglomeration impact of urban agglomeration, these results are dependable. Moreover, the efficiency loss model discovered that pollution and wasteful resource usage were the main reasons behind the drop in ULUE in Northwest China. Finally, the GML index and its constituents revealed that the main force behind ULUE's growth in Northwest China is technological developments. This research provides important policy implications for reducing the gap between eastern and western regions, supporting high-quality development in northwest China, and protecting and intensively using urban land. [ABSTRACT FROM AUTHOR]

The Aalenian–Bajocian (early Middle Jurassic) cooling event (ABCE) was a significant global climate disturbance during the Jurassic. Our analysis of sporopollen fossils from 18 mudstone and silty mudstone samples, collected from the lacustrine-terrestrial succession Xishanyao Formation in the Santanghu Basin, Northwest China, revealed a total of 191 species belonging to 53 genera. We identified an assemblage, the Cyathidites–Deltoidospora–Osmundacidites–Cycadopites assemblage, which dates to the Aalenian–Bajocian (early Middle Jurassic). This assemblage can be further divided into three subassemblages in stratigraphic order: the Cyathidites–Osmundacidites–Cycadopites subassemblage, the Cyathidites–Cycadopites–Psophosphaera subassemblage, and the Cyathidites–Deltoidospora–Osmundacidites subassemblage. We applied the Sporomorph EcoGroup (SEG) model to interpret the paleoclimate features. The sporopollen fossils indicate that the Santanghu Basin underwent a shift in vegetation types, from ground cover vegetation as the dominant form to canopy trees and then back to ground cover vegetation as the primary vegetation during the Aalenian–Bajocian. The SEG model analysis demonstrates that the CCP subassemblage is characterized by a low lowland SEG/upland SEG ratio, low wetter/drier ratio within the lowland SEG, and a low warmer/cooler ratio within the lowland SEG. These characteristics reflect the vegetation's response to the ABCE in the Santanghu Basin. [ABSTRACT FROM AUTHOR]

Improving agricultural eco-efficiency based on resource endowment and development stage is the only means to build a strong agricultural country. Based on the measurement of agricultural eco-efficiency at the city scale in northwest China from 2010 to 2020 using the non-expectation nonradial SE-SBM model, the spatial and temporal differentiation characteristics and influencing factors were analyzed using the indices and methods of difference coefficient, Dagum Gini coefficient, global trend analysis, spatial autocorrelation, and spatial error model. The results indicate the following: (1) The median of agricultural eco-efficiency in northwest China increased from 0.512 to 1.001, with an average annual growth rate of approximately 6.93%; however, the difference in agricultural eco-efficiency between cities showed a narrowing trend. (2) The spatial distribution of agricultural eco-efficiency in northwest China shows hierarchical spatial distribution characteristics. The projection trend line shows a"U-shaped"feature in the north-south direction, whereas the east-west direction gradually shows an "inverted U-shaped"feature in the process of smooth rise from west to east. (3) The results of the spatial error model show that the per workforce arable land area, per capita disposable income of rural residents, and urbanization level positively influence the agricultural eco-efficiency in the northwest China, whereas the agricultural machinery density and fertilizer use intensity negatively influence the agricultural eco-efficiency in the region. [ABSTRACT FROM AUTHOR]

ObjectiveTo assess the oral health-related quality of life (OHRQoL) of adolescents in Northwest China, and to explore the relationship between sociodemographic characteristics, oral health-related behaviors and OHRQoL.MethodsA cross-sectional survey of adolescents aged 12–15 years in Shaanxi, Gansu province and Ningxia Hui Autonomous Region of Northwest China was conducted by stratified cluster random sampling. Oral examinations were performed with World Health Organization (WHO) standards, and the condition of crowns and periodontal was recorded. Adolescents' oral health-related behaviors and OHRQoL were collected by questionnaire. Chi-square test and binary logistic regression analysis were used to examine the relationship.ResultsA total of 7,648 subjects were included. The prevalence of low OHRQoL which defined as a score higher than 0, was 83.8%. A low OHRQoL was most prevalent in Gansu Province and least prevalent in Shaanxi Province. Younger (OR = 0.73, CI = 0.60–0.87), female (OR = 1.27, CI = 1.11–1.44), rural (OR = 1.44, CI = 1.21–1.72), and mother with less education (OR = 0.69, CI = 0.60–0.81) all showed statistically significant influence on teenagers' OHRQoL. From a behavior perspective, teens' OHRQoL was correlated with their frequency of sugar consumption (OR = 1.72, CI = 1.41–2.10), dental appointment rate (OR = 1.29, CI = 1.064–1.57), self-assessment of oral health (OR = 3.09, CI = 2.29–4.19), DMFT index (OR = 1.19, CI = 1.04–1.37), number of teeth calculus (OR = 1.20, CI = 1.01–1.43), and dental trauma (OR = 0.47, CI = 0.39–0.57) over the previous year; however, brushing their teeth was not statistically significant.ConclusionsGenerally speaking, oral health-related behaviors—such as eating more sugary foods and scheduling dental appointments within the last year—have a significant negative impact on the quality of life of adolescents in Northwest China. Female, and adolescents from families with low educational backgrounds are more likely to be affected by such behaviors in their daily lives.

Black carbon (BC) is a pollutant produced by the combustion of fossil fuels and biomass fuels, which has a huge impact on regional climate, atmospheric environment, and human health. In this study, based on MERRA-2 reanalysis data and ground-based observation data, the Mann-Kendall (MK) test and random forest (RF) model were used to explore the spatiotemporal variation characteristics of atmospheric BC concentration in Xinjiang, China and its correlation with meteorological and environmental covariates in 2010–2022. The results showed that the use of MERRA-2 reanalysis data to explore the spatiotemporal variation characteristics of BC concentration in Xinjiang had high reliability (relative average deviation (RAD) = 0.65). From 2010 to 2022, the annual average concentration of atmospheric BC in Xinjiang was 195.40 ± 15.55 ng/m3, and the multi-year average change rate was −0.05%. The winter season had the highest atmospheric BC concentration (145.52 ± 39.31 ng/m3), followed by autumn (124.95 ± 28.82 ng/m3), spring (74.05 ± 9.96 ng/m3), and summer (73.41 ± 5.69 ng/m3). The atmospheric BC concentration had a significant spatial variation, showing two high-BC-concentration areas on the northern slope of the Tianshan Mountains (centered on Urumqi-Changji-Shihezi region) and the urban agglomeration around the Tarim Basin (centered on Kashgar). The RF model analysis showed that meteorological factors including snow depth, surface temperature, and humidity as well as environmental factors including NO2, PM10, and SO2 were the main factors affecting the BC concentration. This work is of great significance for clarifying the accumulation and spatial distribution characteristics of atmospheric BC in northwest China and the factors influencing the atmospheric BC concentration, and helps to raise public attention to the increasingly serious climate change and public health problems caused by BC.

A Cimel Sun‐sky‐lunar photometer (CE318‐T) is designed to perform daytime and nighttime photometric measurements and calculate diurnal cycle of aerosol optical depth (AOD). Nevertheless, the determination of nocturnal AOD from CE318‐T requires a precise knowledge of extraterrestrial lunar irradiance, which significantly changes with moon's phase angle (MPA) and lunar libration in a single night. This study evaluated the 1‐year nocturnal AODs at Lanzhou by using three different methods, which were validated by collocated measurements of DIAL Lidar (as a reference) and Cimel software (as a proxy). The results indicated that three independent approaches could implement a similar performance to compute nocturnal AOD near full moon phase (i.e., MPA = 0°) under moderate aerosol loading. The spectral AOD values at nighttime calculated by ROLO Lunar Langley (Robotic Lunar Observatory model) and Sun‐moon Gain Factor (SMGF) methods are significantly underestimated under low moon's illumination or high MPA (MPA < −47° or MPA > 47°) and distinctly dependent on MPA. The RIMO correction factor (RCF) (ROLO Implementation for Moon photometry Observation correction factor) method could compensate the underestimated extraterrestrial lunar irradiances of ROLO model for about 6.76%–9.78%, and thus greatly improve the calculation accuracy of nighttime AOD. The day/night coherence transition test has demonstrated that we would obtain a good diurnal variation of AODs at Lanzhou after RCF correction. The overall averages of nocturnal AOD440nm differences between Cimel software and ROLO model and SMGF method are 0.064 ± 0.024 and 0.052 ± 0.022, respectively, while the corresponding difference of RCF is less than 0.021 ± 0.014 for all wavelengths, falling within uncertainty range of AERONET AOD products (∼±0.02). The diurnal variations of AODs determined from RCF method agree well with synchronous results of DIAL Lidar, with total mean AOD532nm differences of 0.038 ± 0.024 and 0.023 ± 0.017 in daytime and nighttime, respectively. The spectral AODs computed from RCF method are well consistent with Cimel software, although there are some discrepancies under low AOD cases (AOD440nm < 0.30), and the overall average of AOD440nm differences are less than −0.0053 ± 0.002 and −0.0185 ± 0.013 in daytime and nighttime, respectively. Our results confirmed that the CE318‐T photometer can be reasonably calculated nighttime AOD and Ångström exponent (AE440–870nm) at urban Lanzhou by using three independent methods, although the former two need to be greatly improved under low moon's illumination. The RCF method was proved to reliably calculate nocturnal AOD from moonlight irradiance, which didn't rely on MPA. A more accurate lunar irradiance model needs to be developed to improve the underestimation of current ROLO model. Long‐term climatological information of nocturnal AOD is crucial for comprehensively characterizing the diurnal variations of aerosol optical properties and atmospheric boundary layer structure during the winter at typical northern city of China, which deserves to be further investigated in the future. Plain Language Summary: Aerosol optical depth (AOD) is an essential physical quantity for characterizing total aerosol concentration and investigating its environmental and climatic effects. Newer photometer technology is increasing our ability to passively observe AODs at nighttime, using the moon as the light source. In this study, we determined the moon calibration coefficients of CE318‐T photometer at Lanzhou and compared the nocturnal AOD with collocated active Lidar observations. The three independent methods could implement a similar performance to compute nocturnal AOD near full moon phase under moderate aerosol loading. Although the RIMO correction factor (Robotic Lunar Observatory [ROLO] Implementation for Moon photometry Observation correction factor) method could compensate the underestimated extraterrestrial lunar irradiances of ROLO model for about 6.76%–9.78%, and greatly improve the calculation accuracy of nighttime AOD, with an accuracy of 0.021 ± 0.014, a more accurate lunar irradiance model needs to be developed to improve the underestimation of current ROLO model. Key Points: The nocturnal aerosol optical depths (AODs) calculated by Robotic Lunar Observatory and Sun‐moon Gain Factor methods are significantly underestimated under low moon's illumination and dependent on moon's phase angle (MPA)The RIMO correction factor (RCF) method can be reliably calculated nocturnal AOD from moonlight irradiance at urban Lanzhou, which didn't rely on MPABoth daytime and nighttime AODs computed from RCF method are well consistent with Cimel software and synchronous measurement of DIAL Lidar [ABSTRACT FROM AUTHOR]

Changes in precipitation and its causes under future warming scenarios in Northwest China are of great concern. Based on the dynamical downscaling results of the Weather Research and Forecasting model (WRF), this study quantitatively identified the contribution of local evaporation and external moisture transport to future precipitation changes in western and eastern Northwest China (WNWC and ENWC) by calculating the precipitation recycling ratio (PRR). The results showed that the WRF could reasonably reproduce the observed spatial and temporal distribution of precipitation and evaporation during the historical reference period of 1985–2014. Under the 1.5 and 2.0°C stabilized warming scenarios from 2071 to 2100, there is a stronger precipitation growth in WNWC than in ENWC, and the PRR generally increases in WNWC and decreases in ENWC. Further analysis indicates that external moisture transport is the dominant contributor to the increased precipitation in all cases with its contribution exceeding 70%, while the difference of precipitation growth in two sub‐regions arises from the summer moisture transport at the southern boundary as the inflow in WNWC and outflow in ENWC. Compared to the negligible contribution of evaporation in ENWC (less than 7%), evaporation contributes more than 23% to the precipitation increase in WNWC under future warming scenarios, which may be related to the strong land‐atmosphere coupling there. Furthermore, an additional warming of 0.5°C leads to an increase in precipitation for both sub‐regions, which is mainly due to the contribution of external moisture transport. Plain Language Summary: In this study, we discuss the relative contributions of evaporation and moisture transport to precipitation changes in Northwest China under 1.5/2.0°C stabilized warming scenarios. With Northwest China (NWC) dividing it into two sub‐regions of western and eastern parts, we find that although the western NWC has less precipitation during the reference period of 1985–2014, the increase in precipitation is about twice that of the eastern NWC under the warming scenarios. The contribution of evaporation to the increased precipitation is greater in the western NWC compared with the reference period, which may indicate the accelerating hydrological cycle in western NWC. Moisture transport is the main contributor to the increase in precipitation and is also the main reason for the difference in precipitation changes between the two sub‐regions, mainly due to differences in summer moisture transport across the southern boundary. This work provides a scientific basis for assessing water resources in Northwest China under future warming scenarios. Key Points: External moisture transport contributes more than 70% of precipitation in Northwest China, both in terms of mean and variabilityContribution of evaporation to the precipitation increase is stronger in western Northwest China, due to its strong land‐atmosphere couplingThe difference in moisture transport between the two regions is mainly due to changes in southern border moisture transport in summer [ABSTRACT FROM AUTHOR]

The intricate interplay between water resources, land resources, energy systems, and carbon emissions has emerged as a prominent discourse in academic research. Nonetheless, there remains a dearth of comprehensive research dedicated to fostering environmentally friendly and low-carbon development through systematic integration and coordination efforts. This study aimed to fill this gap by integrating the coupling mechanism of the Water-Land-Energy-Carbon (WLEC) system, thereby constructing an evaluation index framework that assesses coordinated developments in Northwest China's WLEC system. It scrutinizes the security levels within the Water-Land-Energy (WLE) subsystem while conducting quantitative analyses on the degrees of coupling coordination within the WLEC systems, alongside their associated hindering factors. The preliminary findings were as follows: Firstly, the safety development within the WLE system demonstrates a positive trend across Northwest China, with notable advancements primarily observed in the Qinghai and Gansu provinces. In 2021, all five Northwestern provinces exhibited moderate levels of safe development, except for the Qinghai province, which transitioned from moderate to robust. Secondly, the coupling coordination degree of the WLEC system across the five provinces has consistently illustrated an upward trajectory over the years. However, as of 2021, the system remains in a state characterized by marginal disorder. Notably, the Qinghai and Gansu provinces have shown particularly encouraging upward trends, with the Shaanxi province also making notable progress. Conversely, Xinjiang has declined since 2017 due to negative interactions between the subsystems of water, soil, energy, and carbon emissions. Thirdly, spatial variations exist in the distribution patterns between the provinces regarding the influence of obstructing factors on indicators related to coupled coordinated development, such as per capita arable land area, per capita energy consumption, per capita carbon emissions, per capita construction land area, and the proportion of groundwater water in the total amount of water supply, which demonstrated an increasing trend. These findings carry significant practical implications for actively and steadily promoting carbon peaking and carbon neutrality in Northwest China. [ABSTRACT FROM AUTHOR]

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Paleo-oil reservoir is of great importance to understand hydrocarbon enrichment mechanism and hydrocarbon exploration potential, but is yet poorly investigated in Kuqa Depression. The occurrence of the paleo-oil reservoir in Dabei area was proved by quantitative grain fluorescence (QGF) and fluid inclusion petrography. Development history of the paleo-oil reservoir was reconstructed through: (1) oil-source correlation; (2) time coupling of source rock maturation, porosity evolution and migration pathways. The impact of paleo-oil reservoir on tight-gas accumulation was consequently discussed. Results suggest that considerable oil was accumulated in the K1bs reservoir with paleo oil-water contact in Dabei 2 Well and Dabei 201 Well at 5 800 and 6 040 m, respectively. Crude oil was primarily sourced from Triassic source rocks with Jurassic source rocks of secondary importance, which was at oil generation window (0.7%–1.1% Ro) during 9–6 and 7.5–5 Ma, respectively. The occurrence of K1bs tight reservoir (porosity < 12%) was about 25 Ma, while faults and associated fractures at Kelasue structural belt were developed approximately from 8 to 3.5 Ma. Therefore, the tight oil accumulation was formed during 8–5 Ma. The paleo-oil reservoir in Dabei 1 gas field was destroyed by the evaporation fractionation in later stage. [ABSTRACT FROM AUTHOR]

Assessment of social-ecological system resilience is a reliable means of characterizing the system’s ability to respond and recover in response to crisis events. This study takes Northwest China as the research area and aims to assess the spatiotemporal evolutionary trends of social-ecological system resilience levels. Driving force-Pressure-Meteorological constraint-State-Impact-Response(DPWSIR) model is proposed to construct the social-ecological system resilience evaluation system innovatively. The G1 entropy weight method is used to determine the index weight, and the comprehensive index method is used to calculate the social-ecological system resilience level values, evaluate the resilience of arid cities social-ecological systems in Northwest China from 2015 to 2021, and determine the resilience grades. The results demonstrate that: (1) The core status of regional central cities is highlighted, in general, the “center-periphery” spatial structure characteristics gradually stabilize. The resilience levels of regional central cities, such as Hohhot, Baotou, Xi’an, Lanzhou, Xining, Yinchuan, and Urumqi, are as high as 0.37, 0.43, 0.414, 0.41, 0.43, 0.58, and 0.39, respectively. (2) In the study area, the meteorological constraint resilience index showed a “flat-to-sudden decline” trend, with the inflection point of the sharp decline occurring in 2020. The decline in the resilience index value in arid cities is caused by the increase in precipitation and temperature, which is manifested as the result of “warming and humidification”. (3) Meteorological factors, as the direct influencing factors of sandstorms, are the most critical to the assessment of the resilience of arid cities social-ecological systems. The relative percentage difference (RPD) is used to characterize the relative difference between the traditional model (DPSIR) and the improved model (DPWSIR). In areas for example Jinchang(29%), which is close to the dust sources and greatly affected by sandstorms, the differences in the social-ecological systems resilience are large and the RPD values are significant. Therefore, the DPWSIR model is more suitable for arid cities. This study provides scientific reference for the formulation of ecological environment protection policies and resilience improvement strategies for cities affected by sandstorms.

The concentration of potentially toxic elements (PTEs) in soils of different land-use types varies depending on climatic conditions and human. Topsoil samples were collected in Northwest China to investigate PTE pollution and risk in different land uses, and thereby estimate the risk of various pollution sources. The results showed that human activity had an impact on PTE concentrations in the study area across all land use types, with farmland, grassland, woodland, and the gobi at moderate pollution levels and the desert at light pollution levels. Different PTE sources pose different risks depending on the land-use type. Apart from deserts, children are exposed to carcinogenic risk from a variety of sources. A mixed natural and agricultural source was the main source of public health risk in the study area, contributing 38.7% and 39.0% of the non-carcinogenic and 40.7% and 35.5% of the carcinogenic risks, respectively. Monte Carlo simulations showed children were at a higher health risk from PTEs than adult s under all land uses, which ranked in severity as farmland > woodland > grassland > gobi > desert. As and Ni has a higher probability of posing both a non-carcinogenic and a carcinogenic risk to children. Sensitivity analysis showed that the contribution of parameters to the assessment model of PTEs exhibited the following contribution pattern: concentration > average body weight > ingestion rate > other parameters. The PTEs affecting the risk assessment model were not common among different land use types, where the importance distribution pattern of each parameter was basically the same in woodland, grassland, and farmland, and Ni contributed the most to carcinogenic risk. However, Cr contributed the most to the carcinogenic risk in the desert and gobi.

Abstract The inland river basins of northwestern China are structured as mountain-basin systems. Water resources originate in the flow-producing area (FPA), are utilized and operated in the oasis area and are dissipated in the desert area. In this study, a Soil and Water Assessment Tool (SWAT) model was constructed in the Manas River Basin (MRB) FPA. Meanwhile, it simulated climate change and runoff evolution trends in the FPA of the MRB under different four climate change scenarios of Coupled Model Intercomparison Project Phase 5. The main findings showed that (1) the years 1979–1980 were chosen as the model warm-up period, 1979–2000 as the model calibration period and 2001–2015 as the model validation period to complete the construction of the SWAT model for MRBFPA. From 1981 to 2015, three performance parameters indicated that the model accuracy meets the requirements (NSE = 0.81, R 2 = 0.81 and PBIAS = 1.44) and can be used for further studies; (2) the hydrological elements (e.g. runoff, potential evapotranspiration, evapotranspiration, soil water content, snowmelt) in the MRBFPA were analysed by the constructed SWAT model; (3) the climate change in the MRBFPA is close to the RCP 8.5 scenario, and the future changes in water resources under this scenario will range from 659 to 2308 (million)m3. Compared to the multi-year historical mean value (12.95 × 108 m3), the future fluctuation in the amount of water resources available in this basin is increasing.

Northwest China is known for its Majiayao‐style Neolithic painted pottery which has received much praise for its high level of craftsmanship, yet its chain of production, in particular the step of raw material selection, is still poorly understood. To fill this lacuna, the present study explores the raw materials used in producing these wares from a geological and technological perspective. At its core stands the first geoarchaeological survey conducted around the eponymous site of Majiayao which collected 47 samples of raw materials suitable for ceramic production including clay, loess and rocks, which were all analysed macroscopically. A selection was analysed using thin‐section petrography, and a subset of the clay and loess samples were subjected to firing experiments. Additionally, three clay samples were analysed by scanning electron microscope with energy‐dispersive X‐ray spectrometer to understand their composition and behaviour in ceramic production. These were then compared to archaeological ceramics, thus providing insights into raw‐material availability and selection that will be of importance not only for research on Majiayao‐style pottery but also for later‐period ceramics produced in the area. This research shows how an archaeologically informed geological survey can contribute insights into human–environment interaction in early pottery production, especially the interplay between raw‐material availability, technological know‐how and potters' choices. [ABSTRACT FROM AUTHOR]

Revealing the water use pattern of plants influenced by coal-mining-caused land subsidence is crucial to understand plant–water interactions and guide ecological restoration. However, available information on herbaceous plants, the dominant species in most arid and semi-arid regions with abundant coal resources, remains inadequate. We investigated the water use patterns of Stipa bungeana Trin. by measuring soil water content, root distribution, and stable isotopes of hydrogen (δ2H) and oxygen (δ18O) of soil water and plant stem water both before and after a rainfall event. The results revealed that prior to rainfall, both areas exhibited a low soil water content with no discernible difference in soil drought. However, the soil waters δ2H and δ18O were found to be more enriched at varying depths within the subsidence area, indicating a heightened level of soil evaporation. Both soil water content and soil water isotopic composition responded sensitively to rainfall, with rainfall primarily replenishing the shallow layer (0–20 cm), thereby reflecting an infiltration mode dominated by piston flow. More water seeped into deeper soil layers in the subsidence area compared to the non-subsidence area, with more preferential flow. Before rainfall, the sources of plant water uptake were consistent both at shallow and deep soil layers, implying that the proportion of water uptake gradually decreased with increasing depth. After rainfall, the sources of plant water uptake differed slightly between the two soil layers. The plants in non-subsidence and subsidence areas dominantly extracted soil water at depths greater than 10 cm and 20 cm, respectively. The root system in the subsidence area was more developed than that in the non-subsidence area. Plant water uptake was primarily influenced by the spatial distribution of roots, as well as the post-rainfall water distribution, regardless of whether they were in the subsidence area or not. Although land subsidence affected soil water transport, the water uptake pattern of Stipa bungeana Trin. was similar before and after rainfall, indicating the adaptive growth of plants through their roots in the subsidence area. The high adaptability of herbs such as Stipa bungeana Trin. makes them a viable option for vegetation restoration in subsidence areas. This study has significant implications for evaluating plant–water relationships in subsidence areas due to coal mining, thereby providing a fundamental basis and valuable reference for ecological restoration and management strategies within such affected regions. [ABSTRACT FROM AUTHOR]

In this research, we initially examined the key atmospheric circulation pattern influencing the occurrence of dust storms in Northwest China during spring (February–May). We then investigated the drivers impacting atmospheric circulation over the Mongolian Plateau and southern Central Siberia (MPCMS), using NCEP/NCAR reanalysis data and extensive ensemble simulations, and assessed the respective roles of external forces and internal variability. Our results validated a significant inverse correlation between the reduced frequency of spring dust storms in Northwest China post-mid-1980s and heightened geopotential height anomalies over the MPCMS. By scrutinizing five comprehensive ensemble model simulations, we demonstrated that the positive tendencies in atmospheric circulation anomalies over the MPCMS are largely triggered by external forces, accounting for roughly 69.3% of the observed augmentations in the atmospheric circulation index trend from 1954 to 2022. Although the North Atlantic Oscillation is a leading mode of internal variability associated with geopotential height anomalies over the MPCMS, its contribution is comparatively minor. Our findings underline that the primary cause of the decrease in dust storm frequency in Northwest China since the mid-1980s could be ascribed to global warming-related external forces. [ABSTRACT FROM AUTHOR]

The inland river basins of northwestern China are structured as mountain-basin systems. Water resources originate in the flow-producing area (FPA), are utilized and operated in the oasis area and are dissipated in the desert area. In this study, a Soil and Water Assessment Tool (SWAT) model was constructed in the Manas River Basin (MRB) FPA. Meanwhile, it simulated climate change and runoff evolution trends in the FPA of the MRB under different four climate change scenarios of Coupled Model Intercomparison Project Phase 5. The main findings showed that (1) the years 1979–1980 were chosen as the model warm-up period, 1979–2000 as the model calibration period and 2001–2015 as the model validation period to complete the construction of the SWAT model for MRBFPA. From 1981 to 2015, three performance parameters indicated that the model accuracy meets the requirements (NSE = 0.81, R2 = 0.81 and PBIAS = 1.44) and can be used for further studies; (2) the hydrological elements (e.g. runoff, potential evapotranspiration, evapotranspiration, soil water content, snowmelt) in the MRBFPA were analysed by the constructed SWAT model; (3) the climate change in the MRBFPA is close to the RCP 8.5 scenario, and the future changes in water resources under this scenario will range from 659 to 2308 (million)m3. Compared to the multi-year historical mean value (12.95 × 108 m3), the future fluctuation in the amount of water resources available in this basin is increasing. [ABSTRACT FROM AUTHOR]

Inrecent years, there has been a notable increase in utilising multiple criteria decision-making (MCDM) methods in practical problem solving. The advancement of enhanced decision models with greater capabilities, coupled with technologies like geographic information systems (GIS) and artificial intelligence (AI), has fueled the application of MCDM techniques across various domains. To address the scarcity of irrigation water resources in Bortala, Northwest China, the selection of a dam site has been approached using a hybrid model integrating a multipolar Fuzzy set and a plithogenic Fuzzy hypersoft set along with a GIS. This study considered criteria such as a geological layer, slope, soil type, and land cover. Four potential and reasonably suitable dam locations were identified using a dam construction suitability map developed for Bortala. Ultimately, we showcased the benefits of the innovative method, emphasizing an open, transparent, and science-based approach to selecting optimal dam sites through local studies and group discussions. The results highlight the effectiveness of the hybrid approach involving a fuzzy hypersoft set and plithogenic multipolar fuzzy hypersoft set in addressing the challenges of dam site selection. [ABSTRACT FROM AUTHOR]

Mesozoic fossils of frogs are rare in the palaeontological record, particularly those exhibiting soft tissues that offer limited insights into early life-history characteristics. Here we report on a skeletally immature frog from the Lower Cretaceous of northwest China, with egg masses in the body and eggs in the oviduct, indicative of a gravid female. CT reconstruction of the specimen allows referral to Gansubatrachus qilianensis and we assign it as a paratype complementing the diagnosis of the type species. The new fossil, which might represent a younger individual than the holotype of Gansubatrachus, shows that sexual maturation occurred before full adulthood in this frog and provides evidence of death linked to mating behaviour. We also discuss other potential sources of variation and life-history traits of Gansubatrachus. The new finding represents the oldest Early Cretaceous frog preserving in situ eggs and provides a glimpse into ancient anuran development during Mesozoic times. [ABSTRACT FROM AUTHOR]

In arid and semi-arid areas, due to drought climate and shortage of water resources, groundwater is crucial for natural ecological protection and economic development. It serves a dual role as a resource function and an ecological function. However, with the continuous improvement of the exploitation and utilization of groundwater by human activities during rapid economic development, the phenomenon of groundwater overexploitation is becoming more and more serious, which has destroyed the natural balance of groundwater recharge and discharge. As a result, natural vegetation has lost the maintenance of the ecological function of groundwater, and a series of ecological and environmental problems have occurred, such as natural vegetation degradation, land desertification, sandstorms, and so on. In recent years, scholars have carried out research on groundwater resource management and optimization of water resource allocation, trying to solve the problem of water balance in arid regions. However, there is still a lack of comprehensive understanding and systematization regarding influencing factors and degeneration mechanisms related to groundwater's ecological function. By summarizing and analyzing the previous research results, this paper summarizes the influencing factors, evaluation methods, existing problems and future directions of groundwater ecological function research in China to provide a reference for rational exploitation and utilization of groundwater and ecological protection. This paper is divided into four main contents. The first part introduces the definition of groundwater ecological function (GEF); the second part summarizes the research status of influencing factors of GEF, including the groundwater table depth, vegetation root system and lithologic structure of vadose zone, etc.; the third part analyzes the evaluation of groundwater ecological function; the fourth part discusses the existing problems in the study of groundwater ecological functions, and based on the above research the evaluation framework of GEF is proposed with the Shiyang River basin as a case study; and finally, it highlights the future research directions about GEF. [ABSTRACT FROM AUTHOR]

Simple Summary: The effects of Quaternary climatic oscillations on lineage diversification and demography of organisms in drylands have drawn much attention recently. However, little is still known about the processes that shaped the species' spatial genetic structure in areas such as the arid Central Asia, particularly for animals in Northwest China. Here, we investigated the genetic structure and population dynamics of the Zaisan toad-headed agama (Phrynocephalus melanurus) by combining mtDNA phylogeography and species distribution models (SDMs) with range-wide sampling for the first time. Phylogenetic analyses recovered two main Clades, with one from Dzungar and Alakol basins being geographically sub-structured into several groups. Lineage diversification took place in the Pleistocene, coinciding with the drastic aridification caused by Quaternary climatic transitions and drastic activity of the Tianshan Mountains. Moreover, populations of the Dzungar Basin experienced the past expansion and parapatric divergence contributed by isolation-by-distance. SDMs unveiled the species range dynamics since the late Pleistocene, showing expansion in interglacial, and contraction during last glacial maximum and late Holocene periods. Future distribution projections demonstrated drastic habitat loss, suggesting the significance of conservation effort. Our findings highlight the significance of combining genetic approaches with environmental data when evaluating the effects of Pleistocene climatic oscillations. The agamid lizard Phrynocephalus melanurus is restricted to Northwest China (Dzungar Basin) and the adjacent Eastern Kazakhstan (Zaisan and Alakol basins). To elucidate the phylogeography of P. melanurus, we obtained the mitochondrial DNA COI segments of 175 sampled lizards from 44 localities across the whole distribution. Phylogenetic analyses revealed two main Clades comprising five geographically structured lineages (I, IIa, IIb1, IIb2, and IIb3) that fit an isolation-by-distance (IBD) model. The divergence from the most recent common ancestor was dated to ~1.87 million years ago (Ma). Demographic analyses demonstrated lineage-specific response to past climate change: stable population for Clade I, Subclade IIb1; past population expansion for IIb3 since 0.18 Ma, respectively. Bayesian phylogeographic diffusion analyses detected initial spreading at the Saur Mount vicinity, approximately 1.8 Ma. Historical species distribution model (SDM) projected expansion of the suitable habitat in the last interglacial and shift and contraction in the last glacial maximum and Holocene epochs. The SDM predicted a drastic reduction in suitable area throughout the range as a response to future climate change. Our findings suggest that the evolution of P. melanurus followed a parapatric divergence with subsequent dispersal and adaptation to cold and dry environments during the Quaternary. Overall, this work improves our understanding of the lineage diversification and population dynamics of P. melanurus, providing further insights into the evolutionary processes that occurred in Northwest China and adjacent Eastern Kazakhstan. [ABSTRACT FROM AUTHOR]

Understanding the impact of irrigation on the spatiotemporal characteristics of precipitation is important for the ecological stability of the arid region of Northwest China (NWC). In this study, the global climate model MPI-ESM-MR is utilized to provide the initial and lateral boundary conditions for the regional climate model RegCM4, enabling the simulation of the long-term climate of the arid NWC region under two Representative Concentration Pathways (RCPs). The study focuses on analyzing the differences in the spatiotemporal distribution, intensity, and frequency of precipitation before and after irrigation. Furthermore, the study explores the primary factors influencing changes in the spatiotemporal distribution characteristics of precipitation in the irrigation district and its downwind region. The results indicate that RegCM4 performs well in simulating the climatology and diurnal cycle of precipitation in the NWC, particularly excelling during the summer. Large-scale irrigation significantly impacts the structure of summer precipitation, leading to a notable increase in convective precipitation near the irrigation district and surrounding mountain ranges. Anomalous cyclonic circulation and enhanced vertical velocity enhancement provide dynamic conditions for increased precipitation in the irrigation district and surrounding mountainous regions. Furthermore, the evaporation of water vapor resulting from large-scale irrigation serves as an additional source of moisture, contributing to increased precipitation in the irrigation district and its downwind region. Due to the difference in climatic conditions between the western and eastern regions around the irrigated areas, the summer extreme precipitation in the west predominantly increases. At the same time, in the east, it predominantly decreases due to irrigation. The findings of this study contribute to a deeper understanding of the physical mechanisms through which agricultural irrigation influences precipitation in the arid region of the NWC, thereby providing scientific evidence for the sustainable utilization of water resources in the region. [ABSTRACT FROM AUTHOR]

The dissolution and diffusion of CO2 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 CO2 in oil, gas and water, interfacial tension, in-situ oil viscosity distribution, remaining oil saturation distribution, and oil compositions. The results show that CO2 flooding could control water coning and increase oil production. In the early stage of the injection process, CO2 expanded vertically due to gravity differentiation, and extended laterally under the action of strong bottom water in the intermediate and late stages. The CO2 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 CO2 is 0.17 t/t. [ABSTRACT FROM AUTHOR]

Large-scale agricultural activities can intensify atmospheric–terrestrial interactions, of which precipitation recycling plays a critical role. During 1982–2018, irrigated area has dramatically expanded in Northwest China (NWC). In this study, a regional precipitation recycling model—the Brubaker model was used to investigate the precipitation recycling ratio (PRR) and recycled precipitation (RP). Evapotranspiration (ET) estimated by the atmospheric–terrestrial water balance method (A–T) was employed to investigate precipitation recycling. Statistically, there was a turning point in 2002 for the rate in irrigated area increase, from 0.07 × 106 ha/year before 2002–0.217 × 106 ha/year after 2002. There were significant shifts in ET, PRR, and RP in NWC, using the turning point of irrigated area expansion as the line of demarcation. The contribution of the change in irrigated area to PRR increased from 18.3% (1982–2002) to 22.9% (2003–2018) in NWC. Prior to 2002, enhanced RP offset the increased ET by 72.9%. After 2002, the positive effect of irrigated area expansion on precipitation recycling disappeared in NWC. Due to the different climate and irrigation practices at the province level, the variations in irrigated area and their contributions to PRR were examined in three provinces, Xinjiang, Gansu, and Shaanxi. Results based on the Brubaker model and Budyko framework indicate that in Xinjiang and Gansu, the contribution of the irrigated area change after the turning point to PRR were 24.5% and -95.6%, respectively, and there is no potential for continued expansion of irrigated area. In Shaanxi, however, there is potential for continued expansion of irrigated area. The methodology for quantifying the impact of irrigated area change on PRR provides reliable references for the sustainable use of cultivated land and the protection of agricultural water resources.

Since the the dawn of the 21st century, water security has occupied a pivotal position in fostering sustainable development. However, frequency of extreme weather events due to climate change and higher intensity of anthropogenic events, water security problems in Northwest China are becoming increasingly prominent. This paper elucidates water security levels and predicts future trends of Northwest China. Firstly, the Driving Force-Pressure-State-Impact-Response (DPSIR) conceptual framework served as the foundation for the establishment of the water security evaluation index system. Then used the entropy weight method to calculate the weight of indicators and the five-element connection degree method was used to assess the water security levels. The period for the data used in the study was from 2010 to 2019. Finally, a grey prediction model was employed to forecast the water security levels from 2023 to 2030. The findings showed that: (1) From 2010 to 2019, the water security situation gradually developed to a very high level in Northwest China: Shaanxi Province mostly attained a high level, and the water security grades of Ningxia Hui Autonomous Region and Xinjiang Uygur Autonomous Region were mostly at a very low level. (2) Generally, from 2023 to 2030, the water security level will continue to improve. The water security grades of Shaanxi, Gansu, and Qinghai will mostly be at the medium level, while that of Ningxia Hui Autonomous Region and Xinjiang Uygur Autonomous Region will be at the low level. (3) The five dimensions of water security in Northwest China demonstrated a fluctuating yet consistently upward trend. (4) Based on the results, suggestions were put forward regarding water security and sustainable development in Northwest China.

The northwest China is a climate change-sensitive and ecologically vulnerable area. Under the backdrop of global warming, this region exhibits clear characteristics of warming and wetting. In recent years, the causes of climate change in the northwest China has become a widely-focused topic. Previous research has mainly attributed the increase in precipitation to changes in the westerly belt and enhanced local convective activity caused by global warming. South Asia, beside the Tibetan Plateau from the northwest China, is one of the regions with the fastest growth in global atmospheric pollutant emissions. This study utilizes reanalysis data such as ERA5 and MERRA-2. Statistical methods, including Theil-Sen Median trend analysis and Singular Value Decomposition analysis, are employed to analyze the spatiotemporal characteristics of South Asian aerosols, extreme precipitation in the northwest China, and the correlation between the two. The study reveals the existence of two key aerosol-precipitation response areas. Synthetic analysis of the meteorological elements of the response events in both regions is conducted to explore the possible physical mechanisms behind the correlation between South Asian aerosols and precipitation in the northwest China. The result of this study is to provide a new perspective on the causes of extreme precipitation in the arid region of northwest China.

Floian, Early Ordovician trilobites are systematically described and revised based on new material from the middle part of the Duoquanshan Formation of the Shihuigou area, northern Qinghai Province, northwest China. The fauna that lived on the shallow-water carbonate platform comprises three species belonging to two families, i.e., Tsaidamaspis diarmatus, Zhiyia tsinghaiensis, and Liexiaspis sp. indeterminate. It exhibits a strong endemicity to the Olongbluk terrane. The new isoteline genus Zhiyia is established on the basis of the material from the Olongbluk terrane and South China palaeoplate, and is characterized by its: (i) almost obsolete cephalic and pygidial axial furrows; (ii) flattened anterior border and narrow (sag., exsag.) occipital ring; (iii) bilobed hypostome with a shallow median notch and a small triangular median projection; (iv) subsemicircular pygidium with wide pygidial axis and border. Faunal evidence indicates that the palaeogeographic position of the Olongbluk terrane may have been situated closer to the South China palaeoplate rather than the North China palaeoplate during the Floian.