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Northwest China (WTL) is an essential ecological barrier zone of China, an important node of the "Silk Road Economic Belt," and a crucial bearing area for China's execution of the "One Road and One Belt" and "Going Global" strategies. However, its ecology is exceedingly fragile and particularly vulnerable to climate change and human interference. This study explored the spatiotemporal evolution characteristics of vegetation in WTL using NDVI data and investigated its drive mechanisms by geodetector, partial correlation analysis, and residual trend analysis methods. As well as forecasting the trend for vegetation changes. The findings demonstrated that (1) the change in NDVI manifested an overall improvement trend and the distribution in space of NDVI rose from the center to the periphery. 57.07% of the area had a sparse cover of vegetation (NDVI between 0 and 0.2). In addition, about 49% of regions had deterioration tendencies, which were mainly aggregated in HX, QCXDB, QCXDN, and the eastern of QCXQN and QCXXB. (2) The NDVI's shifting trend was unsustainability, and the region of uncertain future accounted for 57.45% of the total, with apparent unsustainability features. (3) The key parameters influencing NDVI spatial distribution were Pre (precipitation), vegetation type, land use type, and soil type. The interaction between two factors enhanced the influence of any single element, which appeared as bivariate and nonlinear enhancements. (4) Both climate variations and human activities have been recognized as key variables affecting NDVI growth. NDVI variance in 73.02% of areas was influenced by the combined effects of climate variations and human activities. However, human activities were the most influential element in NDVI growth, with the relative contributions of 80.28% (19.72% of which was caused by climate variations). These results can be conducive to deepening insights into the local vegetation status, identifying the mechanisms driving vegetation change, and providing scientific recommendations for WTL's ecosystem restoration measures based on actual situations. [ABSTRACT FROM AUTHOR]

The intensification of estrogen non-point source pollution has drawn global attention due to their contribution to ecological environment problems worldwide, and it is critical to develop effective, economic and eco-friendly methods for reducing estrogens pollution. To address the agglomeration and oxidation of nano zero-valent iron (nZVI), biochar-nanoscale zero-valent iron composite (nZVI-biochar) could be a feasible choice for estrogens removal. This study summarized biochar and nZVI-biochar preparation, characterization, and unusual applications for estrone (E1), 17β-estradiol (E2), and estriol (E3) removal. The properties of biochar and nZVI-biochar in characterization, effects of influencing factors on the removal efficiency, adsorption kinetics, isotherm and thermodynamics were investigated. The experiment results showed that nZVI-biochar exhibited the superior removal performance for estrogens pollutants compared to biochar. Based on the quasi-second-order model, estrogens adsorption kinetics were observed, which supported the mechanism that chemical and physical adsorption existed simultaneously on estrogens removal. The adsorption isotherm of estrogens could be well presented by the Freundlich model and thermodynamics studies explained that nZVI-biochar could spontaneously remove estrogens pollutants and the main mechanisms involved π-π interaction, hydrophobic interaction, hydrogen bonding and degradation through ring rupture. The products analyzed by GC–MS showed that estrogens degradation was primarily attributed to the benzene ring broken, and Fe3+ promoted the production of free radicals, which further proved that nZVI-biochar had the excellent adsorption performances. Generally, nZVI-biochar could be employed as a potential material for removing estrogens from wastewater. Highlights: Porous and functional nZVI-biochar was prepared and applied for estrogens removal. nZVI-biochar exhibited high adsorption capacities to estrogens pollutants due to π–π interaction, hydrophobic interaction and hydrogen bonding. The estrogens adsorption process of nZVI-biochar conformed to quasi-second-order kinetics and the Freundlich model. The production of free radicals contributed to the degradation of estrogens. [ABSTRACT FROM AUTHOR]

Clarifying the spatiotemporal variation of crop irrigation water requirement (IWR) under the background of climate change is an essential basis for water resource management, determining the irrigation quota and adjusting the planting structure. Using 61 years of climate data from 205 stations in Northwest China, this study investigated the spatiotemporal variations of climatic factors and IWR during the growth period of five main grain crops (spring wheat, winter wheat, spring maize, summer maize, and rice) and explored the dominant climatic driving factors of IWR variation. Results showed that (1) the IWR of grain crops showed distinct differences. Rice was the highest water consumption crop (mean of 753.78 mm), and summer maize was the lowest (mean of 452.90 mm). (2) The variation trends and average values of IWR of different grain crops have spatial heterogeneity across Northwest China. For most crops, high values and increasing trends of IWR were mainly located in eastern Xinjiang, western Gansu, and western Inner Mongolia. (3) Tmax (maximum temperature), Tmin (minimum temperature), and Peff (effective precipitation) showed an increasing trend during the growth period of each grain crop, while U10 (wind speed at 10 m height), SD (solar radiation), and RH (relative humidity) presented decreasing trends. (4) SD, Tmax, and U10 promoted the increase of grain crops' IWR, while Peff and RH inhibited it. The impacts of climatic factors on the grain crop IWR differed among different regions. Peff was the most influential factor to the IWR of all grain crops in most areas. Therefore, under the premise of a significant increase in T and uncertain precipitation mode in the future, it is urgent to take effective water-saving measures according to the irrigation needs of the region. To cope with the adverse impact of climate change on the sustainable development of agriculture in the northwest dry area, to ensure regional and national food security. [ABSTRACT FROM AUTHOR]

The People's Victory Canal Irrigation Area is a large gravity irrigation area in the middle and lower reaches of the Yellow River. Groundwater hydrochemistry is controlled by geochemical weathering, precipitation, irrigation from the Yellow River diversion, and artificial exploitation. The Piper diagram, hierarchical cluster analysis, Gibbs diagram, and ion proportion coefficient were applied to improve our understanding of the hydrogeochemical evolution. Our results indicated that groundwater ion concentration has prominent spatial zonation characteristics in the study area. The groundwater ion components in the low salinity area are mainly a result of silicate and carbonate weathering, with the major hydrochemical type being HCO3·Cl–Na·Mg and HCO3–Na·Ca. The soil salt content in the low salinity area is low. The main effect of precipitation on groundwater chemical composition is a reduction in groundwater ion concentration by recharge. The groundwater ion concentration near the canal is similar to the Yellow River water. The groundwater ionic components in the high salinity area are mainly affected by weathering, silicate dissolution, and evaporative salt rocks. The water chemical type is SO4·Cl–Na·Mg. Expectedly, the soil salt content is high in the high salinity area. The Yellow River recharge decreased the ion concentration of groundwater near the canal. In addition, the groundwater exploitation increase results in a change in the flow field, affecting the local groundwater chemistry. The groundwater ion concentration increases as the groundwater flow from the high salinity area to the low salinity area. In contrast, the groundwater ion concentration in the high salinity area decreases. We further discuss these results in the context of the complex influence of precipitation, Yellow River diversion irrigation, and artificial exploitation on the hydrogeochemical evolution. [ABSTRACT FROM AUTHOR]

The hydro-fluctuation belt is a vital ecosystem with rich resources and environmental regulation ability. It plays a critical role in maintaining biodiversity, the balance in aquatic-terrestrial ecosystem and water purification. However, the water environmental system in the hydro-fluctuation belt is complex and dynamic with a large number of uncertain factors, and these factors are interrelated, which can be defined as a grey system. This paper evaluated the effects of environmental influencing factors on nitrogen diffusion fluxes at sediment-water interface and determined the main controlling factor by application of grey correlation analysis. The monitoring of nitrogen diffusion fluxes at sediment-water interface in the hydro-fluctuation belt of Danjiangkou reservoir lasted for one year, the index system of environment influencing factors were determined, and the procedures of the grey correlation analysis method were introduced. Analysis results indicate that the main controlling factors for diffusion flux of ammonium, nitrate, nitrite and inorganic nitrogen were dissolved oxygen, temperature, pH and pH, respectively. The nitrogen compounds accumulated in the sediment for a long duration can be transformed into ammonium nitrogen by microorganisms, which increased the nitrogen release risk. Therefore, it is an effective way to regulate the pH in the overlying water to control nitrogen pollution. Since the process of nitrogen migration and transformation can be affected by many direct and indirect influential factors, it is quite difficult to achieve satisfactory nitrogen removal effects by regulating single influential factor. However, it provided a possible new way for sediment nitrogen pollution evaluation and regulation. [ABSTRACT FROM AUTHOR]

Danjiangkou reservoir is the water intake of the north-to-south water transfer middle route project and the largest freshwater lake in Asia. According to the operation mode of the reservoir, a large area is formed in the alternating state of drying-flooding annually and this may cause eutrophication in the aquatic ecosystem. The effects of drying-flooding alteration on nitrogen fluxes in the hydro-fluctuation belt of the Danjiangkou reservoir were investigated by conducting three experimental treatments of long-term (LFD), short-term drying-flooding alternating frequency (SFD), and continuous flooding (CF) with indoor incubation experiment. The results showed that the periodic drying-rewetting state is adverse to the ammonium release. The average exchange fluxes of NH4+-N in treatment LFD, SFD, and CF were -10.27, 11.79, and 48.12 mg m−2 d−1, respectively. The varying frequency of periodic drying-flooding had little influence on the exchange fluxes of TDN (FTDN-LFD = -50.52 mg m−2 d−1, FTDN-SFD = -51.60 mg m−2 d−1), but it affected the exchange fluxes significantly for different forms of nitrogenous compounds; the exchange fluxes of ammonium and nitrate in SFD treatment (11.79 and 3.77 mg m−2 d−1) were higher than those in LFD treatment (-10.27 and 0.43 mg m−2 d−1). Ammonium is the main nitrogen form in the bodies of water with long-term inundation; by extending the drying period of the sediment, the ammonium concentrations decreased while the nitrate concentrations increased. [ABSTRACT FROM AUTHOR]

River eutrophication has become a challenging environmental problem worldwide because of the strong interference of anthropogenic activities and hydraulic structures. The driving mechanism of algae growth in sluice-controlled river reaches (SCRRs) is more complicated than that of natural rivers, because the operation mode of the sluices is an important influencing factor which changes the light and nutrient conditions of the water body. The main purpose of this study was to assess algal growth in SCRRs under external conditions and sluice regulation. In this study, a eutrophication model for SCRRs was developed based on the mechanism of river hydrodynamics and algae growth kinetics, considering the variation in underwater light intensity and nutrient condition. By choosing the light intensity, phosphorus concentration and sluice gate opening size as the influencing factors, 16 different combination conditions were proposed by orthogonal experimental design, and eutrophication of water bodies in the SCRRs was simulated using a eutrophication model. In the scenario design, four gate opening sizes were set, and the light intensity and nutrients were enlarged or reduced based on the original monitoring data. The results showed that both light intensity and nutrient concentration can promote the algal growth within a suitable range, and increasing the gate opening size can inhibit algal growth. [ABSTRACT FROM AUTHOR]

Purpose: To compare the reliability of the whorl-like region with that of the central cornea for accurate assessment of corneal subbasal nerve plexus (SNP) by analyzing the parameter variability of these two anatomical regions in repeated measurements. Methods: Participants were scanned in the central cornea and whorl-like region with in vivo confocal microscopy on three occasions by two examiners within a time span of one week. Coefficients of repeatability (CoR), intra-class correlation coefficient (ICC), and Bland–Altman scatter plots with 95% limits of agreement (LOA) in the central cornea and whorl-like region were calculated, respectively, based on the nerve fiber length, then the inter-observer and intra-observer agreement were compared between these two anatomical regions. Results: The inter-observer ICC was 0.945, the inter-observer CoR was 0.052, the intra-observer ICC was 0.936, and the inter-observer CoR was 0.046, with narrow 95% LOA within 1 standard deviation in the whorl-like region, whereas the inter-observer ICC was 0.600, the inter-observer CoR was 0.207, the intra-observer ICC was 0.206, and the intra-observer CoR was 0.253, with 95% LOA nearly threefold wider than the standard deviation in the central cornea. Conclusions: Nerve parameter in the whorl-like region showed higher inter-observer and intra-observer agreement than that of the central cornea. The whorl-like region is a more reliable site for accurate assessment of SNP. [ABSTRACT FROM AUTHOR]

Drought is a major natural hazard that can have devastating impacts on regional agriculture, water supply, ecological environment and social economy. Extreme events, including droughts, are expected to be severer and more frequent because of climate warming. This paper presents an analysis of observed changes and future projections of meteorological drought in the Daqing River Basin (DRB), North China, based on the modified Standardized Precipitation Index (SPImod). Observed changes of meteorological drought are analyzed based on the precipitation series of 26 meteorological stations from 1971 to 2011, and future projections are made under two representative concentration pathways (RCPs 4.5 and 8.5) from 2021 to 2050. The result shows a change from wet to dry detected in most areas of the DRB in summer, winter and annual series. The drought risk is higher under the condition of "OR" and "AND" return period during the observation period, and the high-risk regions cover a large area. The drought risk from 2021 to 2050 will increase across the basin under RCP 4.5 and RCP 8.5, compared with which in the base period from 1971 to 2000. Most regions will be at a higher drought risk under the condition of "OR" return period, and the area with high-risk under RCP 4.5 is slightly larger than that under RCP 8.5. Under the condition of "AND" return period, the high-risk regions will cover the area from the northwest to the northeast, while the area of high-risk regions under RCP 8.5 will be larger than that under RCP 4.5. The result of this paper will be helpful for performing an efficient water resource management in the DRB under the impacts of global warming and climate change. [ABSTRACT FROM AUTHOR]

A comparison between gross irrigation water use (GIWU) in fields and allocated irrigation water rights amount (AIWA) is critical for evaluating any system of water rights allocation. GIWU in fields under different precipitation probabilities has been rarely calculated and compared with AIWA using households' survey data. This study developed a method for calculating the GIWU of crops under different precipitation probabilities using field survey data from 391 households and the monitoring data of wells in Chengan County, China. AIWA was compared with the calculated GIWU and irrigation quota. Results showed that AIWA is too small to satisfy the GIWU of the principle crops. The GIWU of main cropping patterns under a precipitation probability of 75% was curtailed between 43 and 77% to fulfill AIWA. AIWA cannot support any cropping patterns when precipitation is lower than the precipitation percentile of 75%. In this condition, farmers are restricted to planting apples, cotton, and sweet potatoes. The uncertainty in precipitation was not fully considered, and the participation of farmers in water rights allocation in Chengan County was limited, which may adversely influence the income and food security of farmers. [ABSTRACT FROM AUTHOR]

Autophagy is a basic cellular process that decomposes damaged organelles and aberrant proteins. Dysregulation of autophagy is implicated in pathogenesis of neurodegenerative disorders, including Parkinson's disease (PD). Pharmacological compounds that stimulate autophagy can provide neuroprotection in models of PD. Nanoparticles have emerged as regulators of autophagy and have been tested in adjuvant therapy for diseases. In this present study, we explore the effects of quantum dots (QDs) that can induce autophagy in a cellular model of Parkinson's disease. CdTe/CdS/ZnS QDs protect differentiated rat pheochromocytoma PC12 cells from MPP-induced cell damage, including reduced viability, apoptosis and accumulation of α-Synuclein, a characteristic protein of PD. The protective function of QDs is autophagy-dependent. In addition, we investigate the interaction between quantum dots and autophagic pathways and identify beclin1 as an essential factor for QDs-induced autophagy. Our results reveal new promise of QDs in the theranostic of neurodegenerative diseases. [ABSTRACT FROM AUTHOR]