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Climate change has a significant impact on water resources. Forecasts and simulations of climate runoff processes are essential for assessing the impact of global climate change on runoff variations. This study focuses on the upper Taohe River Basin, which is an important watershed in the semi-arid regions of northwest China. To assess the runoff in the upper Taohe River Basin and the responses to climate change, the SWAT hydrological model was used to analyze future climate change scenarios and their effects on water resources. The results indicate that the minimum temperature would increase gradually in the 21st century and that the minimum temperature change would be more significant than the maximum temperature change, which indicates that minimum temperature changes would make an obvious contribution to future regional warming. Under RCP2.6, the average precipitation would decrease; at the same time, under RCP4.5 and RCP8.5, the average precipitation would increase. In the future, under different climate scenarios, the runoff will exhibit droughts and flood disasters. These research results provide scientific support for water resource utilization and management in the Taohe River Basin. [ABSTRACT FROM AUTHOR]

Despite the importance of the Yellow River to China, climate change for the middle reaches of the Yellow River Basin (YRB) has been investigated far less than for other regions. This work focuses on future changes in mean and extreme climate of the YRB for the near-term (2021–2040), mid-term (2041–2060), and far-term (2081–2100) future, and assesses these with respect to the reference period (1986–2005) using the latest REgional MOdel (REMO) simulations, driven by three global climate models (GCMs) and assuming historical and future [Representative Concentration Pathway (RCP) 2.6 and 8.5] forcing scenarios, over the CORDEX East Asia domain at 0.22° horizontal resolution. The results show that REMO reproduces the historical mean climate state and selected extreme climate indices reasonably well, although some cold and wet biases exist. Increases in mean temperature are strongest for the far-term in winter, with an average increase of 5.6 °C under RCP 8.5. As expected, the future temperatures of the warmest day (TXx) and coldest night (TNn) increase and the number of frost days (FD) declines considerably. Changes to mean temperature and FD depend on elevation, which could be explained by the snow-albedo feedback. A substantial increase in precipitation (34%) occurs in winter under RCP 8.5 for the far-term. Interannual variability in precipitation is projected to increase, indicating a future climate with more extreme events compared to that of today. Future daily precipitation intensity and maximum 5-day precipitation would increase and the number of consecutive dry days would decline under RCP 8.5. The results highlight that pronounced warming at high altitudes and more intense rainfall could cause increased future flood risk in the YRB, if a high GHG emission pathway is realized. [ABSTRACT FROM AUTHOR]

The Qilian Mountains region, located on the northeastern Tibetan Plateau, is a region in western China that is sensitive to climate change and serves as an important ecological security barrier. Previous studies mostly used meteorological stations to study climate change in the Qilian Mountains; however, due to the known distribution limitations (scarcity and inhomogeneity) of meteorological stations in mountainous areas, relevant results remain inconclusive. To address this issue, we used 30 meteorological stations in and around the Qilian Mountains and the China meteorological forcing dataset (CMFD) with a spatial resolution of 0.1° × 0.1° to comprehensively analyse the spatiotemporal distribution of and variation in the air temperature over the Qilian Mountains, with a particular focus on elevation-dependent warming (EDW); then, land surface albedo data from the ERA5-Land and MODIS products were employed to interpret the EDW. The results showed that the annual mean lapse rate in the Qilian Mountains is −0.56 °C/100 m. From 1979 to 2018, the air temperature over the Qilian Mountains experienced a significant upwards trend with an annual mean rate of 0.39 °C/decade, the maximum rate occurring in December–February (DJF, 0.56 °C/decade) and the minimum rate occurring in June–August (JJA, 0.28 °C/decade). Spatially, significant warming was found in most areas of the Qilian Mountains, and a slight cooling trend was found in the north and southeast. Unlike other typical areas, the Qilian Mountains showed reversed EDW during 1979–2018, i.e., the increasing trends in air temperature decreased with elevation, which was mainly caused by the reversal in EDW over the 1999–2008 period and could be largely explained by the change in land surface albedo. • A high-precision assimilation data is used to analyse air temperature changes in the Qilian Mountains. • Evident elevational dependency of air temperature change is reported. • The Qilian Mountains experienced a significant warming, but with seasonal and spatial differences. • The reversed elevation-dependent warming is detected and attributed to surface albedo change. [ABSTRACT FROM AUTHOR]

It is of great significance to explore the remediation pattern in actual heavy metal (HM) contaminated sites. The field trial was carried out to research the remediation effect of biochar near a lead-zinc smelter in Feng County, China, under the rotation condition of different crops. This kind of cultivation mode is very representative in northern of China. And the pattern of production and restoration is suitable for scarce land resources and large food demand in China. The changes of soil physiochemical properties with the biochar addition, crop growth and the accumulated HMs by crops were focused on. The results showed the biochar application was excellent in improving soil nutrient elements and crop growth. The contents of TK were more obvious than those of TN and TP, with an increase of 2.6%–28.2% compared with the controls (without the addition of biochar). The yield of first season crops, i.e., soybean and corn, increased by 30%–42% and 34%–61%, respectively, and the second season crops, i.e., rape and wheat, with the increment of 25%–41% and 9%–29%, respectively. The availability forms of Cd and Pb decreased by 1.07–10.0% and 2.92–8.35%, respectively. While the improvement on the status of the HMs accumulated by crops was disappointing. The contents of HMs accumulated by crops increased to varying degrees (e.g., Pb and Zn in root, Cu and Pb in grain, and Cd in stems and leaves). Moreover, the concentrations of HMs in seeds of crops were higher than the limited levels given by the Chinese directive. Considering the results of the study and food safety, it is suggested to change the nature of the land around the smelter into woodland or construction land to prohibit the cultivation of food crops in this area. [Display omitted] • The effect of biochar on the HM availability under rotation pattern was explored. • The contents of THC had a significant relationship with the dose of biochar. • Biochar has more obvious effects on immobilizing Cu, Pb and Cd than Zn. • The factors controlling the changes of samples in the same season were similar. [ABSTRACT FROM AUTHOR]

The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau. Based on the observed soil temperature data (hourly data from 1 January 2001 to 31 December 2005) obtained by GAME-Tibet, the diurnal, seasonal and interannual variations in soil temperature at BJ site (31.37° N, 91.90° E; 4509 a.s.l.) near Naqu in the central Tibetan Plateau were analyzed. Results showed that the average diurnal variation in soil temperature at 4 and 20 cm depth can be described as sinusoidal curve, which is consistent with the variation of solar radiation. However, the average diurnal variation in soil temperature under 60 cm was very weak. The average diurnal amplitude in soil temperature decreased by the exponential decay function with the increase of soil depth (R=0.92, p<0.01). It is demonstrated that the average diurnal maximum soil temperature decreased by the exponential decay function with the increase of soil depth (R =0.78, p<0.01). In contrast, the average diurnal minimum soil temperature increased by the exponential grow function with increasing of soil depth (R=0.86, p<0.01). There were a linear negative correlation between the average annual maximum Ts and soil depth (R=0.96, p<0.01), a logarithmic function relationship between the average annual minimum soil temperature and soil depth (R=0.92, p<0.01). The average seasonal amplitude in soil temperature followed the exponential decay function with the increase of soil depth (R=0.98, p<0.01). The mean annual soil temperature in each layer indicated a warming trend prominently. During the study period, the mean annual soil temperature at 4, 20, 40, 60, 80, 100, 130, 160, 200 and 250 cm depth increased by 0.034, 0.041, 0.061, 0.056, 0.062, 0.050, 0.057, 0.051, 0.047 and 0.042 °C /a, respectively. [ABSTRACT FROM AUTHOR]

Brassica juncea L. is an attractive species in PTMs contaminated soil remediation ascribing to its high tolerance under stress and great accumulation capacity of metals. To identify the potential Cd/Zn accumulators from numerous different Chinese mustard cultivars for practical phytoremediation is a promising strategy in China. In present work, a pot experiment involving elevated Cd/Zn concentrations was performed among 21 cultivars. Regarding physiological and biochemical indicators under Cd/Zn stress, principal component analysis and cluster analysis were used for cultivar tolerance evaluation and classification. Results showed that BJ (Bao Jie, var. involutus) cultivar was distinguished as a potential phytoremediation candidate comparing with other cultivars. Moreover, BJ accumulated the maximum Cd content of 63.85 and 77.29 mg kg−1 DW in shoots and roots, respectively, and the maximum Zn uptake by BJ were 6693 and 4777 mg kg−1 DW in shoots and roots, respectively. Accordingly, BJ had the highest Cd/Zn tolerance, remarkable accumulation and translocation capacity (accumulation factor (AF) > 1 for Cd and Zn; translocation factor (TF) > 0.8 for Cd and TF > 1 for Zn). In addition, the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities of the mustard increased initially under low Cd/Zn stress as compared to the control and then declined dramatically with the increasing metals exposure concentration. Therefore, the antioxidant enzymes may play a protective role against reactive oxygen species (ROS) under low Cd/Zn stress, whereas the defense system might be collapsed under relatively high Cd/Zn stress. Furthermore, the enhanced Cd/Zn exposure led to an increase in malondialdehyde (MDA) content in the mustard cultivars, indicating that Cd/Zn had induced more severe oxidative stress and higher degree of lipid peroxidation had occurred. The present investigation results indicated that BJ (Bao Jie, var. involutus), as a native cultivar, can be further applied in the field trials of phytoremediation practices in contaminated soil. Image 1 • Chinese mustard cultivars for Cd/Zn phytoremediation were screened. • BJ (Bao Jie, var. involutus) has the highest tolerance under Cd/Zn stress. • BJ was identified as the most promising candidate for phytoremediation. • The antioxidant system protected the plants from the injury of Cd/Zn stress. BJ (Bao Jie, var. involutus) was identified as a potential candidate for phytoremediation from various Chinese mustard (Brassica juncea L.) cultivars. [ABSTRACT FROM AUTHOR]

Climate change has greatly affected regional hydrological processes at temporal and spatial scales, and much attention has been focused on how runoff changed under the background of global warming in recent years. In northwest China, Taohe River provides major water resource to several semi-arid regions. To quantificationally estimate water resource, the influence of precipitation and temperature on runoff needs to be further studied. In this paper, hydro-meteorological data from 1956 to 2014 were used to analyze the changes of temperature, precipitation and runoff based on Mann–Kendall test and double cumulative curve method. The main findings were that the temperature had a significant increasing trend (0.26 °C/10a), while precipitation showed an insignificant increasing trend (0.9 mm/10a). Runoff exhibited a significant decreasing trend (− 2.7 × 108 m3/10a) and break point of the runoff occurred in 1987. Thus, compared with benchmark value during the period 1956–1987, runoff after 1987 was reduced to 70.7% of the previous level on average, from 37.5 × 108 m3 in 1956–1987 to 26.5 × 108 m3 in 1988–2014, with a decreasing rate of 29.3%; and runoff changes in each month were all decreased after 1987, particularly in September by 41.29%. Double cumulative curve and correlation results revealed that precipitation was the dominant factor controlling changes in runoff and their correlation coefficient reached up to 0.73. The magnitude of precipitation dominated runoff from April to October, accounting for more than 95% of the total annual runoff. However, runoff decreased more dramatically than precipitation after 1987, which indicated that there were some non-precipitation factors, like the increase of evaporation caused by temperature rise and human activities, responsible for the decline of runoff from 1988 to 2014. Some large-scale climate factors had a good tele-connective relation with variability of runoff. Overall, this study exhibited a scientific fact of runoff decreasing in the upper Taohe River basin and aimed to provide a basic direction for reasonable allocation of water resources by the Taohe River Diversion Project sustainably. [ABSTRACT FROM AUTHOR]

In situ stabilization and phytoextraction are considered as two convenient and effective technologies for the remediation of toxic elements (TEs) in soils. However, the effectiveness of these two remediation technologies together on the bioavailability and phytoextraction of TEs in field trials has not been explored yet. Specifically, the remediation potential of fly ash (FA; as stabilizing agent) and ryegrass (as a TE accumulator) intercropped with a target crop for soil polluted with multiple TEs has not been investigated yet, particularly in long-term field trials. Therefore, in this study, a six-month combined remediation field experiment of FA stabilization and/or ryegrass intercropping (IR) was carried out on the farmland soils contaminated with As, Cd, Cr, Cu, Hg, Ni, Pb and Zn where Zanthoxylum bungeanum (ZB) trees as native crops were grown for years. The treatments include soil cultivated alone with ZB untreated- (control) and treated-with FA (FA), produced by burning lignite in Shaanxi Datong power plant, China, soil cultivated with ZB and ryegrass untreated- (IR) and treated-with FA (FA + IR). This was underpinned by a large-scale survey in Daiziying (China), which showed that the topsoils were polluted by Cd, Cu, Hg and Pb, and that Hg and Pb contents in the Zanthoxylum bungeanum fruits exceeded their allowable limits. The TEs contents in the studied FA were lower than their total element contents in the soil. The DTPA-extractable TEs contents of the remediation modes were as follows: FA < FA + IR < IR < control. Notably, TEs contents in the ZB fruits were lowest under the FA + IR treatment, which were decreased by 27.6% for As, 42.3% for Cd, 16.7% for Cr, 30.5% for Cu, 23.1% for Hg, 15.5% for Ni, 33.2% for Pb and 38.1% for Zn compared with the control treatment. Whereas the FA + IR treatment enhanced TEs contents in ryegrass shoots and roots, and the TEs contents in ryegrass shoots were below their regulatory limits for fodder crops. The findings confirmed that the combined remediation strategy, i.e., FA (with low content of TEs) stabilization effect and intercropping of ZB (target crop) and ryegrass (accumulating plant) could provide a prospective approach to produce target plants within safe TEs thresholds with greater economic benefits, while remediating soils polluted with multiple TEs and mitigating the potential ecological and human health risk. Those results are of great applicable concern. [Display omitted] • Combined soil remediation by fly ash (FA) and intercropping (IR) is proposed. • Zanthoxylum Bungeanum used as a target crop and ryegrass as a hyperaccumulator. • FA + IR decreased the bioavailability of soil toxic elements (TEs) in soil. • TEs content was reduced in Zanthoxylum Bungeanum fruit while increased in ryegrass. • Passivation of FA and competition of ryegrass made soils and crops safe. [ABSTRACT FROM AUTHOR]

Different forms of precipitation (snow, sleet, and rain) have divergent effects on the Earth's surface water and energy fluxes. Therefore, discriminating between these forms, and exploring their climatology and variations are of significant importance, especially under a changing climate. In this study, a state-of-the-art parameterization scheme with wet-bulb temperature (T w), relative humidity (RH), surface air pressure, and elevation as inputs was used to estimate the climatologies and trends of the different forms of precipitation and their temperature thresholds across China mainland from 1961 to 2016. The results indicate that on average, only 9.6% and 0.8% of the total precipitation (602.9 mm) over China during 1961–2016 occurred as snow and sleet. The trends of the different forms of precipitation varied greatly from region to region and from season to season. The regionally averaged annual precipitation, rainfall, and snowfall across China significantly increased at rates of 11.4 mm/decade, 11.0 mm/decade, and 1.0 mm/decade, respectively, whereas the annual sleet decreased at a rate of −0.3 mm/decade. The region-wide snow (rain) fraction significantly increased (decreased) in Northwestern China (NWC) and Northern China (NC) but significantly decreased (increased) on the Tibetan Plateau (TP). Given the heterogeneous RH and complex topography, the T w values at which snow-sleet and sleet-rain occurred with equal frequency—that is, T s and T r , varied significantly across China, averaging 0.1 °C and 0.3 °C, respectively. However, most regions experienced significant decreases in the temperature thresholds (especially T r), with decreasing RH. Almost all of the regions also experienced significant increases in T w , especially on the TP and during the winter and spring. The adverse combination of the increase in T w and the decrease in the temperature thresholds resulted in more precipitation falling as rain, although the snowfall slightly increased in some regions. • Around 9.6% and 0.8% of the total precipitation over China occurred as snow and sleet during 1961–2016. • The temperature thresholds for distinguishing precipitation forms varied significantly across China. • Annual mean precipitation, rainfall, and snowfall across China significantly increased, whereas annual sleet decreased. • The region-wide snow (rain) fraction increased (decreased) in Northwestern China and Northern China but decreased (increased) significantly in the Tibetan Plateau. • The adverse combination of the increase in wet-bulb temperature and the decrease in the temperature thresholds resulted in more precipitation falling as rain. [ABSTRACT FROM AUTHOR]

China has the largest area of glaciers situated within the middle- and low-latitude areas worldwide. Rapid changes in mountain glaciers across western China in the last decades have not only affected glacial runoff and hazards but also had profound impacts on ecosystems and socioeconomic activities in the extensive cold and arid regions of Asia and even beyond. Therefore, research on glacier change is of significant importance for regional sustainability. This study re-analyzes the first and second Chinese Glacier Inventories (CGI-1 and CGI-2) and summarizes available in-situ observation-based studies on glacier mass balance and length to provide a spatially explicit and coherent national-scale assessment of glacier changes and associated influencing factors in recent decades. We connect the glaciers between CGI-1 (from the 1950s to the 1980s) and CGI-2 (from the 2000s to the 2010s) one by one to explore the area, volume, and Equilibrium Line Altitude (ELA) changes at both the individual glacier and river basin scales for the first time. The results show that the long-term area and volume changes in China's glaciers during the area-weighted average period from CGI-1 (around 1969) to CGI-2 (around 2008) were − 5.6%/decade and − 5.3%/decade, respectively, with a mean ELA change of 12.5 m/decade. Approximately 17.2% of the total number of glaciers in CGI-1 disappeared, only 5.5% of the glaciers advanced, and the majority of glaciers decreased in size during the period between CGI-1 and CGI-2, which was characterized by a shrinkage in area and volume and a rise in ELA or division into multiple branches. In-situ observation-based analysis shows that glacier length has reduced since at least the 1960s on average, and their trends have accelerated since the 1990s. The negative trend of mass balance was slightly larger than that of the reference glaciers globally during 1960–2019, while the mean mass loss in any given decade was lower than that of the global mean. The changes have different regional characteristics. Overall, the shrinkage increased from the interior to the southeast in the Tibetan Plateau and decreased from the northeast to the southwest in northern Xinjiang, including the Chinese Tien Shan Mountains. Climatic conditions, as reflected in annual mean temperature and precipitation, are the primary causes of different spatiotemporal patterns of glacier change. A significant positive correlation is observed between annual absolute area/volume changes and snowfall variations, and a significant negative correlation is found with rainfall variations, but there is no significant correlation between the indicators of air temperature and glacial changes at the river basin scale. Additionally, other local-scale factors, such as glacial morphology and topographic conditions, have exerted profound impacts on glacier retreat for individual glaciers. • A spatially explicit national-scale assessment of China's glacier changes over the past several decades was conducted. • Out of the 34,578 glaciers examined, of which 17.2% disappeared, 5.5% expanded, and the majority decreased in size. • The glacier area, volume, and ELA changes were quantified at both the individual glacier and river basin scales. • The area and ELA change rates were -5.6%/decade and 12.5 m/decade, averaged over all China's glaciers during 1970–2009. • In-situ observed and reconstructed glacier mass balance showed an increasingly more negative trend during 1961–2019. • In-situ observation-based glacier length has decreased since the 1960s, and the trend has accelerated since the 1990s. • Climatic and topographic conditions, and glacial morphology were analysed as main influencing factors for glacier changes. [ABSTRACT FROM AUTHOR]