Millions of dollars are being spent on gully rehabilitation to help reduce excess fine sediment delivery to the Great Barrier Reef(GBR).There is an urgent need for(i)prioritisation of active gullies for rehabilitation...Millions of dollars are being spent on gully rehabilitation to help reduce excess fine sediment delivery to the Great Barrier Reef(GBR).There is an urgent need for(i)prioritisation of active gullies for rehabilitation and(ii)the development of methodologies to inform the effectiveness of remediation.In this study we analyse DEMs of Difference derived from 0.5 m resolution 2-3 year interval multi-temporal LiDAR data collected pre and post rehabilitation at three variable gully morphologies in the Burdekin catchment.Our analysis indicates that the highest annual average fine sediment erosion rates for the untreated control gullies occur at the linear gully(53.38 t ha^(-1)y^(-1))followed by linear-alluvial gully(34.24 t ha^(-1)y^(-1))and least at the alluvial gully(14.41 t ha^(-1)y^(-1)).The proportional loss or export of fine sediment from the gullies in their un-treated condition ranges from∼68 to 90%of what is eroded,and when the gullies are treated the proportion of fine sediment that is retained in the gully proportional to what is eroded increases to∼60%at all sites.Without pre-treatment baseline erosion rates,and additional post treatment LiDAR captures,it is difficult to quantify the treatment effectiveness.Our results offer insights in the erosion mechanisms within different geomorphic gully morphologies and rehabilitation effects in these erosional landforms.This study provides crucial knowledge of gully dynamics that can be coupled with other lines of evidence for better prioritisation of rehabilitation in the GBR catchments.展开更多
Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is...Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is greater than two tonnes of lint per hectare due to improved plant genetics and crop management. However, this average yield is well below the yield that would be expected from the amount of N fertiliser used. It is clear from the recent studies that across all growing regions, conversion of fertiliser N into lint is not uniformly occurring at application rates greater than 200-240 kg·hm;of N. This indicates that factors other than N availability are limiting yield, and that the observed nitrogen fertiliser use efficiency（NFUE） values may be caused by subsoil constraints such as sodicity and compaction. There is a need to investigate the impact of subsoil constraints on yield and NFUE.Gains in NFUE will be made through improved N fertiliser application timing, better targeting the amount of fertiliser applied for the expected yield, and improved soil N management. There is also a need to improve the ability and confidence of growers to estimate the contribution of soil N mineralisation to the crop N budget. Many Australian studies including data that could theoretically be collated in a meta-analysis suggest relative NFUE values as a function of irrigation technique; however, with the extensive list of uncontrolled variables and few studies using non-furrow irrigation, this would be a poor substitute for a single field-based study directly measuring their efficacies. In irrigated cotton, a re-examination of optimal NFUE is due because of the availability of new varieties and the potential management and long-term soil resilience implications of the continued removal of mineralised soil N suggested by high NFUE values. NFUE critical limits still need to be derived for dryland systems.展开更多
To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province,East China,the main stream and the Shanxi Zhaoshandu Reservoir in the dow...To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province,East China,the main stream and the Shanxi Zhaoshandu Reservoir in the downstream were chosen as the study area,for which 22 sampling sites were designated.Sampling was conducted in September 2021,January,May,and July 2022.Phytoplankton species were identified from both quantitative samples and in-vivo observations.Phytoplankton was quantified by direct counting.Results show that there were 98 species belonging to 6 phyla and 78 genera.In addition,to clarify the niches of the dominant phytoplankton species and their interspecific association,the dominance index was calculated,and a comprehensive analysis was conducted including niche width,niche overlap value,ecological response rate,overall association,chi-square test,and the stability.The phytoplankton community exhibited characteristics of a Cyanobacteria-Chlorophyta-Diatom type community,showing higher diversity in spring and lower diversity in summer.Among 11 dominants phytoplankton species from 3 phyla,both frequency and dominance degree varied seasonally,of which Microcystis sp.was the dominant species in Spring,Autumn,and Winter.The niche widths of the dominant species ranged from 0.234 to 0.933,and were categorized into three groups.The niche overlap values of the 11 dominant species ranged from 0.359 to 0.959,exhibiting significant seasonal differences-highest in winter followed by autumn,spring,and summer in turn.The overall correlation among dominant species in all four seasons revealed a non-significant negative association,resulting in an unstable community structure.A significant portion(84.2%)of species pairs displayed positive associations,suggesting a successional pattern where Diatoms dominated while other dominant species shared resources and space.Despite this pattern,stability measurements indicated that the dominant species community remained unstable.Therefore,careful monitoring is recommended for p展开更多
Near-surface wind speed exerts profound impacts on many environmental issues,while the long-term(≥60 years)trend and multidecadal variability in the wind speed and its underlying causes in global high-elevation and m...Near-surface wind speed exerts profound impacts on many environmental issues,while the long-term(≥60 years)trend and multidecadal variability in the wind speed and its underlying causes in global high-elevation and mountainous areas(e.g.,Tibetan Plateau)remain largely unknown.Here,by examining homogenized wind speed data from 104 meteorological stations over the Tibetan Plateau for 1961-2020 and ERA5 reanalysis datasets,we investigated the variability and long-term trend in the near-surface wind speed and revealed the role played by the westerly and Asian monsoon.The results show that the homogenized annual wind speed displays a decreasing trend(-0.091 m s^(−1)per decade,p<0.05),with the strongest in spring(-0.131 m s^(−1)per decade,p<0.05),and the weakest in autumn(-0.071 m s^(−1)per decade,p<0.05).There is a distinct multidecadal variability of wind speed,which manifested in an prominent increase in 1961-1970,a sustained decrease in 1970-2002,and a consistent increase in 2002-2020.The observed decadal variations are likely linked to large-scale atmospheric circulation,and the correlation analysis unveiled a more important role of westerly and East Asian winter monsoon in modulating near-surface wind changes over the Tibetan Plateau.The potential physical processes associated with westerly and Asian monsoon changes are in concordance with wind speed change,in terms of overall weakened horizontal air flow(i.e.,geostrophic wind speed),declined vertical thermal and dynamic momentum transfer(i.e.,atmospheric stratification thermal instability and vertical wind shear),and varied Tibetan Plateau vortices.This indicates that to varying degrees these processes may have contributed to the changes in near-surface wind speed over the Tibetan Plateau.This study has implications for wind power production and soil wind erosion prevention in the Tibetan Plateau.展开更多
Lakes in the Tibetan Plateau are considered sensitive responders to global warming Variations in physical features of lake systems such as surface area and water level are very helpful in understanding regional respon...Lakes in the Tibetan Plateau are considered sensitive responders to global warming Variations in physical features of lake systems such as surface area and water level are very helpful in understanding regional responses to global warming in recent decades. In this study multi-source remote sensing data were used to retrieve the surface area and water level time series of five inland lakes in the south-central part of the Tibetan Plateau over the past dec- ades. Changes in water level and surface area of the lakes were investigated. The results showed that the water level of three lakes （Puma Yumco, Taro Co, Zhari Namco） increased, with expanding surface area, while the water levels of the other two lakes （Paiku Co, Mapam Yumco） fell, with shrinking area. The water levels of the lakes experienced remarkable changes in 2000-2012 as compared with 1976-1999. Spatially, lakes located at the southern fringe of the Tibetan Plateau showed consistency in water level changes, which was different from lakes in the central Tibetan Plateau.展开更多
As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law a...As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law and mechanism regarding the influence of the confining pressure constraints on 3D morphological features of natural fractures.First,fracture surfaces were obtained by true triaxial compression test and 3D laser scanning.Then 3D morphological parameters of fractures were calculated by using Grasselli’s model.The results show that the failure mode of granites developed by true triaxial stress can be categorized into tension failure and shear failure.Based on the spatial position of fractures,they can be divided into tension fracture surface,S-1 shear fracture surface,and S-2 shear fracture surface.Micro-failure of the tension fracture surface is dominated by mainly intergranular fracture;the maximum height of asperities on the fracture surface and the 3D roughness of fracture surfaces are influenced by σ_(3) only and they are greater than those of shear fracture surfaces,a lower overall uniformity than tension fracture surface.S-1 shear fracture surface and S-2 shear fracture surface are dominated by intragranular and intergranular coupling fracture.The maximum height of asperities on the fracture surface and 3D roughness of fracture surface are affected by σ_(1),σ_(2),and σ_(3).With the increase of σ_(2) or σ_(3),the cutting off of asperities on the fracture surface becomes more common,the maximum height of asperities and 3D roughness of fracture surface further decrease,and the overall uniformity gets further improved.The experimental results are favorable for selecting technical parameters of enhanced geothermal development and the safety of underground mine engineering.展开更多
The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear...The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified.展开更多
In Australia,the proportion of forest area that burns in a typical fire season is less than for other vegetation types.However,the 2019-2020 austral spring-summer was an exception,with over four times the previous max...In Australia,the proportion of forest area that burns in a typical fire season is less than for other vegetation types.However,the 2019-2020 austral spring-summer was an exception,with over four times the previous maximum area burnt in southeast Australian temperate forests.Temperate forest fires have extensive socio-economic,human health,greenhouse gas emissions,and biodiversity impacts due to high fire intensities.A robust model that identifies driving factors of forest fires and relates impact thresholds to fire activity at regional scales would help land managers and fire-fighting agencies prepare for potentially hazardous fire in Australia.Here,we developed a machine-learning diagnostic model to quantify nonlinear relationships between monthly burnt area and biophysical factors in southeast Australian forests for 2001-2020 on a 0.25°grid based on several biophysical parameters,notably fire weather and vegetation productivity.Our model explained over 80%of the variation in the burnt area.We identified that burnt area dynamics in southeast Australian forest were primarily controlled by extreme fire weather,which mainly linked to fluctuations in the Southern Annular Mode(SAM)and Indian Ocean Dipole(IOD),with a relatively smaller contribution from the central Pacific El Niño Southern Oscillation(ENSO).Our fire diagnostic model and the non-linear relationships between burnt area and environmental covariates can provide useful guidance to decision-makers who manage preparations for an upcoming fire season,and model developers working on improved early warning systems for forest fires.展开更多
In this review,advances in the understanding of the controlling factors and physical mechanisms of tropical cyclogenesis(TCG)are summarized from recent(2018–2022)research on TCG,as presented in the Tenth Internationa...In this review,advances in the understanding of the controlling factors and physical mechanisms of tropical cyclogenesis(TCG)are summarized from recent(2018–2022)research on TCG,as presented in the Tenth International Workshop on Tropical Cyclones(IWTC-10).Observational,theoretical,and numerical modeling studies published in recent years have advanced our knowledge on the influence of large-scale environmental factors on TCG.Furthermore,studies have shown clearly that appropriate convective coupling with tropical equatorial waves enhances the development chances of TCG.More recently,illuminating research has been carried out on analyzing the mechanisms by which oscillations and teleconnections(El Ni˜no Southern Oscillation(ENSO)in particular)modulate TCG globally,in association with changes in the sea surface temperature(SST).In addition to this,recent research has diligently addressed different aspects of TCG.Multiple studies have reported the applicability of unified theories and physical mechanisms of TCG in different ocean basins.Recently,research has been carried out on TCG under different flow pattern regimes,dry air intrusion,importance of marsupial pouch,genesis of Medicanes,wind shear,convection and vertical structure.Furthermore,studies have discussed the possibility of near equatorial TCG provided that there is enough supply of background vertical vorticity and relatively low vertical wind shear.Progress has been made to understand the role of climate change on global and regional TCG.However,there are still significant gaps which need to be addressed in order to better understand TCG prediction.展开更多
Efficient destruction of cyanide by thermal decomposition with ferric oxide addition was proposed. The mechanism of destruction of sodium cyanide with or without ferric oxide addition under various conditions was exam...Efficient destruction of cyanide by thermal decomposition with ferric oxide addition was proposed. The mechanism of destruction of sodium cyanide with or without ferric oxide addition under various conditions was examined by XRD, DSC-TG, and chemical analysis technologies. In the absence of ferric oxide, sodium cyanide decomposes at 587.4 ℃ in air and 879.2 ℃ in argon atmosphere. In the presence of ferric oxide, about 60% of sodium cyanide decomposes at 350 ℃ for 30 min in argon, while almost all sodium cyanide decomposes within 30 min in air or O2 with mass ratio of ferric oxide to sodium cyanide of 1:1. The increase of ferric oxide addition, temperature, and heating time facilitates the destruction of sodium cyanide. It is believed that with ferric oxide addition, NaCN reacts with Fe2O3 to form Na4Fe(CN)6, Na2CO3, NaNO2 and Fe3O4 in argon. NaCN decomposes into NaCNO, Na4Fe(CN)6, minor NaNO2, and the formed NaCNO and Na4Fe(CN)6 further decompose into Na2CO3, CO2, N2, FeOx, and minor NOx in air or O2.展开更多
Homogeneity and heterogeneity are two totally different concepts in nature.At the particle length scale,rocks exhibit strong heterogeneity in their constituents and porosities.When the heterogeneity of porosity obeys ...Homogeneity and heterogeneity are two totally different concepts in nature.At the particle length scale,rocks exhibit strong heterogeneity in their constituents and porosities.When the heterogeneity of porosity obeys the random uniform distribution,both the mean value and the variance of porosities in the heterogeneous porosity field can be used to reflect the overall heterogeneous characteristics of the porosity field.The main purpose of this work is to investigate the effects of porosity heterogeneity on chemical dissolution front instability in fluid-saturated rocks by the computational simulation method.The related computational simulation results have demonstrated that:1) since the propagation speed of a chemical dissolution front is inversely proportional to the difference between the final porosity and the mean value of porosities in the initial porosity field,an increase in the extent of the porosity heterogeneity can cause an increase in the mean value of porosities in the initial porosity field and an increase in the propagation speed of the chemical dissolution front.2) An increase in the variance of porosities in the initial porosity field can cause an increase in the instability probability of the chemical dissolution front in the fluid-saturated rock.3) The greater the mean value of porosities in the initial porosity field,the quicker the irregular morphology of the chemical dissolution front changes in the supercritical chemical dissolution systems.This means that the irregular morphology of a chemical dissolution front grows quicker in a porosity field of heterogeneity than it does in that of homogeneity when the chemical dissolution system is at a supercritical stage.展开更多
Introduction:Over the past two decades,China has experienced rapid economic development,which has not only led to a rapid increase in the use of raw materials but has also created environmental problems.This research ...Introduction:Over the past two decades,China has experienced rapid economic development,which has not only led to a rapid increase in the use of raw materials but has also created environmental problems.This research analyzes the environmental impacts of resource extraction in China at the provincial level,and fully considers the environmental impact of various resources extraction.In addition,it is the first time to quantitatively study the spatial pattern and evolution characteristics of the environmental impacts of China’s resource extraction from multiple perspectives by means of spatial visualization.Outcomes:The results showed that the center of gravity of abiotic depletion potential(ADP)moved northwest,respiratory inorganics(RI)moved southwest and global warming potential(GWP)moved west.The results of the standard deviation ellipse showed that RI and GWP varied over time and space,while ADP showed a discrete trend.In addition,the distribution of the four in the northeast-southwest direction became more prominent.Conclusion:To mitigate the environmental impacts of resource extraction,we recommend that regional governments implement measures to control environmental impacts in the provinces within the distributed ellipse and design targeted policies based on actual conditions.展开更多
Integrated water quantity and quality simulations have become a popular tool in investigations on global water crisis.For integrated and complex models,conventional uncertainty estimations focus on the uncertainties o...Integrated water quantity and quality simulations have become a popular tool in investigations on global water crisis.For integrated and complex models,conventional uncertainty estimations focus on the uncertainties of individual modules,e.g.,module parameters and structures,and do not consider the uncertainties propagated from interconnected modules.Therefore,this study investigated all the uncertainties of integrated water system simulations using the GLUE(i.e.,generalized likelihood uncertainty estimation)method,including uncertainties associated with individual modules,propagated uncertainties associated with interconnected modules,and their combinations.The changes in both acceptability thresholds of GLUE and the uncertainty estimation results were also investigated for different fixed percentages of total number of iterations(100000).Water quantity and quality variables(i.e.,runoff and ammonium nitrogen)were selected for the case study.The results showed that module uncertainty did not affect the runoff simulation performance,but remarkably weakened the water quality responses as the fixed percentage increased during calibration and validation periods.The propagated uncertainty from hydrological modules could not be ignored for water quality simulations,particularly during validation.The combination of module and propagated uncertainties further weakened the water quality simulation performance.The uncertainty intervals became wider owing to an increase in the fixed percentages and introduction of more uncertainty sources.Moreover,the acceptability threshold had a negative nonlinear relationship with the fixed percentage.The fixed percentages(20.0%-30.0%)were proposed as the acceptability thresholds owing to the satisfactory simulation performance and noticeably reduced uncertainty intervals they produced.This study provided methodological foundations for estimating multiple uncertainty sources of integrated water system models.展开更多
Drylands cover approximately 41%of the global land surface and provide homes to more than two billion people. Collectively,drylands constitute the largest terrestrial biome on the planet,and despite their low producti...Drylands cover approximately 41%of the global land surface and provide homes to more than two billion people. Collectively,drylands constitute the largest terrestrial biome on the planet,and despite their low productivity per land area compared to other ecosystems, they have a major impact on the ecological functioning and climate of our planet through carbon storage, albedo, dust production, and water cycling [1].展开更多
An abundance of data from seismic and geodetic monitoring has provided new insight into dyke propagation and emplacement mechanisms.These studies show that faulting and fracturing is part of the magma
Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of pero...Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.展开更多
High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estima...High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estimate FVC at a 30-m/15-day resolution over China by taking advantage of the spatial and temporal information from different types of sensors: the 30-m resolution sensor on the Chinese environment satellite(HJ-1) and the 1-km Moderate Resolution Imaging Spectroradiometer(MODIS). The algorithm was implemented for each main vegetation class and each land cover type over China. First, the high spatial resolution and high temporal frequency normalized difference vegetation index(NDVI) was acquired by using the continuous correction(CC) data assimilation method. Then, FVC was generated with a nonlinear pixel unmixing model. Model coefficients were obtained by statistical analysis of the MODIS NDVI. The proposed method was evaluated based on in situ FVC measurements and a global FVC product(GEOV1 FVC). Direct validation using in situ measurements at 97 sampling plots per half month in 2010 showed that the annual mean errors(MEs) of forest, cropland, and grassland were-0.025, 0.133, and 0.160, respectively, indicating that the FVCs derived from the proposed algorithm were consistent with ground measurements [R2 = 0.809,root-mean-square deviation(RMSD) = 0.065]. An intercomparison between the proposed FVC and GEOV1 FVC demonstrated that the two products had good spatial–temporal consistency and similar magnitude(RMSD approximates 0.1). Overall, the approach provides a new operational way to estimate high spatial resolution and high temporal frequency FVC from multiple remote sensing datasets.展开更多
基金We would like to acknowledge the Australian Government Reef Trust GBR LiDAR Project(Environmental Research and Analysis Project SON2615371)the Australian Governments National Environmental Science Program(NESP)Tropical Water Quality Hub Projects(Projects 2.1.4 and 5.9)+1 种基金the Queensland Government funded Landholders Driving Change(LDC)Program(LRP17-003 and LME17-009)CSIRO for providing funding for this study.Thankyou also to NQ Dry Tropics staff and associated contractors for managing and delivering the rehabilitation projects,to Peter Zund(QDES)and Seonaid Philip(CSIRO)for their support obtaining soil descriptions and samples,and to Shawn Darr and the Queensland Government for access to the gully density mapping data(Fig.1).We would also like to thank the property owners for allowing access to their properties and involvement in the projects-Darren Watts and Family,Warren Woodhouse and Christian and Melissa Cormack.We thank the editor and reviewers for review comments which have significantly improved this paper.
文摘Millions of dollars are being spent on gully rehabilitation to help reduce excess fine sediment delivery to the Great Barrier Reef(GBR).There is an urgent need for(i)prioritisation of active gullies for rehabilitation and(ii)the development of methodologies to inform the effectiveness of remediation.In this study we analyse DEMs of Difference derived from 0.5 m resolution 2-3 year interval multi-temporal LiDAR data collected pre and post rehabilitation at three variable gully morphologies in the Burdekin catchment.Our analysis indicates that the highest annual average fine sediment erosion rates for the untreated control gullies occur at the linear gully(53.38 t ha^(-1)y^(-1))followed by linear-alluvial gully(34.24 t ha^(-1)y^(-1))and least at the alluvial gully(14.41 t ha^(-1)y^(-1)).The proportional loss or export of fine sediment from the gullies in their un-treated condition ranges from∼68 to 90%of what is eroded,and when the gullies are treated the proportion of fine sediment that is retained in the gully proportional to what is eroded increases to∼60%at all sites.Without pre-treatment baseline erosion rates,and additional post treatment LiDAR captures,it is difficult to quantify the treatment effectiveness.Our results offer insights in the erosion mechanisms within different geomorphic gully morphologies and rehabilitation effects in these erosional landforms.This study provides crucial knowledge of gully dynamics that can be coupled with other lines of evidence for better prioritisation of rehabilitation in the GBR catchments.
基金funded by the Australian Government Department of Agriculture and Water Resourcesthe Cotton Research and Development Corporation's Rural Research and Development for Profit Project "More profit from nitrogen:enhancing the nutrient use efficiency of intensive cropping and pasture systems"funded by the Cotton Research and Development Corporation's PhD scholarship
文摘Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is greater than two tonnes of lint per hectare due to improved plant genetics and crop management. However, this average yield is well below the yield that would be expected from the amount of N fertiliser used. It is clear from the recent studies that across all growing regions, conversion of fertiliser N into lint is not uniformly occurring at application rates greater than 200-240 kg·hm;of N. This indicates that factors other than N availability are limiting yield, and that the observed nitrogen fertiliser use efficiency（NFUE） values may be caused by subsoil constraints such as sodicity and compaction. There is a need to investigate the impact of subsoil constraints on yield and NFUE.Gains in NFUE will be made through improved N fertiliser application timing, better targeting the amount of fertiliser applied for the expected yield, and improved soil N management. There is also a need to improve the ability and confidence of growers to estimate the contribution of soil N mineralisation to the crop N budget. Many Australian studies including data that could theoretically be collated in a meta-analysis suggest relative NFUE values as a function of irrigation technique; however, with the extensive list of uncontrolled variables and few studies using non-furrow irrigation, this would be a poor substitute for a single field-based study directly measuring their efficacies. In irrigated cotton, a re-examination of optimal NFUE is due because of the availability of new varieties and the potential management and long-term soil resilience implications of the continued removal of mineralised soil N suggested by high NFUE values. NFUE critical limits still need to be derived for dryland systems.
基金Supported by the National Key Scientific Research Project(No.2018YFC1508200)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX 23_0714)+1 种基金the China Scholarship Council(No.202206710066)the Construction Project of Wenzhou Hydrology High quality Development Pilot Zone(No.WZSW-GZLFZXXQ-202105)。
文摘To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province,East China,the main stream and the Shanxi Zhaoshandu Reservoir in the downstream were chosen as the study area,for which 22 sampling sites were designated.Sampling was conducted in September 2021,January,May,and July 2022.Phytoplankton species were identified from both quantitative samples and in-vivo observations.Phytoplankton was quantified by direct counting.Results show that there were 98 species belonging to 6 phyla and 78 genera.In addition,to clarify the niches of the dominant phytoplankton species and their interspecific association,the dominance index was calculated,and a comprehensive analysis was conducted including niche width,niche overlap value,ecological response rate,overall association,chi-square test,and the stability.The phytoplankton community exhibited characteristics of a Cyanobacteria-Chlorophyta-Diatom type community,showing higher diversity in spring and lower diversity in summer.Among 11 dominants phytoplankton species from 3 phyla,both frequency and dominance degree varied seasonally,of which Microcystis sp.was the dominant species in Spring,Autumn,and Winter.The niche widths of the dominant species ranged from 0.234 to 0.933,and were categorized into three groups.The niche overlap values of the 11 dominant species ranged from 0.359 to 0.959,exhibiting significant seasonal differences-highest in winter followed by autumn,spring,and summer in turn.The overall correlation among dominant species in all four seasons revealed a non-significant negative association,resulting in an unstable community structure.A significant portion(84.2%)of species pairs displayed positive associations,suggesting a successional pattern where Diatoms dominated while other dominant species shared resources and space.Despite this pattern,stability measurements indicated that the dominant species community remained unstable.Therefore,careful monitoring is recommended for p
基金the National Natural Science Foundation of China(42101027)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,2019QZKK0606)+3 种基金the Fundamental Research Funds for the Central Universities of China(2022NTST18)Opening Foundation of Engineering Center of Desertification and Blown-Sand Control of Ministry of Education at Beijing Normal University(2023-B-2)the IBER-STILLING project,funded by the Spanish Ministry of Science.L.M.was founded by an International Postdoc grant from the Swedish Research Council(2021-00444)SWS was supported by‘Development of Advanced Science and Technology for Marine Environmental Impact Assessment'of Korea Institute of Marine Science&Technology Promotion(KIMST)funded by the Ministry of Oceans and Fisheries of South Korea(20210427).
文摘Near-surface wind speed exerts profound impacts on many environmental issues,while the long-term(≥60 years)trend and multidecadal variability in the wind speed and its underlying causes in global high-elevation and mountainous areas(e.g.,Tibetan Plateau)remain largely unknown.Here,by examining homogenized wind speed data from 104 meteorological stations over the Tibetan Plateau for 1961-2020 and ERA5 reanalysis datasets,we investigated the variability and long-term trend in the near-surface wind speed and revealed the role played by the westerly and Asian monsoon.The results show that the homogenized annual wind speed displays a decreasing trend(-0.091 m s^(−1)per decade,p<0.05),with the strongest in spring(-0.131 m s^(−1)per decade,p<0.05),and the weakest in autumn(-0.071 m s^(−1)per decade,p<0.05).There is a distinct multidecadal variability of wind speed,which manifested in an prominent increase in 1961-1970,a sustained decrease in 1970-2002,and a consistent increase in 2002-2020.The observed decadal variations are likely linked to large-scale atmospheric circulation,and the correlation analysis unveiled a more important role of westerly and East Asian winter monsoon in modulating near-surface wind changes over the Tibetan Plateau.The potential physical processes associated with westerly and Asian monsoon changes are in concordance with wind speed change,in terms of overall weakened horizontal air flow(i.e.,geostrophic wind speed),declined vertical thermal and dynamic momentum transfer(i.e.,atmospheric stratification thermal instability and vertical wind shear),and varied Tibetan Plateau vortices.This indicates that to varying degrees these processes may have contributed to the changes in near-surface wind speed over the Tibetan Plateau.This study has implications for wind power production and soil wind erosion prevention in the Tibetan Plateau.
基金We thank the Climate Data Center, National Meteorological Information Center, China Me- teorological Administration, for providing the long-time meteorological data of the four field stations. This research was jointly supported by The ＂Strategic Priority Research Program （B）＂ of the Chinese Academy of Sciences （Grant XDB03030406）, and the National Natural Science Foundation of China （Grant 41371218, 41165011）.
文摘Lakes in the Tibetan Plateau are considered sensitive responders to global warming Variations in physical features of lake systems such as surface area and water level are very helpful in understanding regional responses to global warming in recent decades. In this study multi-source remote sensing data were used to retrieve the surface area and water level time series of five inland lakes in the south-central part of the Tibetan Plateau over the past dec- ades. Changes in water level and surface area of the lakes were investigated. The results showed that the water level of three lakes （Puma Yumco, Taro Co, Zhari Namco） increased, with expanding surface area, while the water levels of the other two lakes （Paiku Co, Mapam Yumco） fell, with shrinking area. The water levels of the lakes experienced remarkable changes in 2000-2012 as compared with 1976-1999. Spatially, lakes located at the southern fringe of the Tibetan Plateau showed consistency in water level changes, which was different from lakes in the central Tibetan Plateau.
基金support from the National Natural Science Foundation of China(Nos.51974173 and 52004147)the Natural Science Foundation of Shandong Province(Nos.ZR2020QD122 and ZR2020QE129).
文摘As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law and mechanism regarding the influence of the confining pressure constraints on 3D morphological features of natural fractures.First,fracture surfaces were obtained by true triaxial compression test and 3D laser scanning.Then 3D morphological parameters of fractures were calculated by using Grasselli’s model.The results show that the failure mode of granites developed by true triaxial stress can be categorized into tension failure and shear failure.Based on the spatial position of fractures,they can be divided into tension fracture surface,S-1 shear fracture surface,and S-2 shear fracture surface.Micro-failure of the tension fracture surface is dominated by mainly intergranular fracture;the maximum height of asperities on the fracture surface and the 3D roughness of fracture surfaces are influenced by σ_(3) only and they are greater than those of shear fracture surfaces,a lower overall uniformity than tension fracture surface.S-1 shear fracture surface and S-2 shear fracture surface are dominated by intragranular and intergranular coupling fracture.The maximum height of asperities on the fracture surface and 3D roughness of fracture surface are affected by σ_(1),σ_(2),and σ_(3).With the increase of σ_(2) or σ_(3),the cutting off of asperities on the fracture surface becomes more common,the maximum height of asperities and 3D roughness of fracture surface further decrease,and the overall uniformity gets further improved.The experimental results are favorable for selecting technical parameters of enhanced geothermal development and the safety of underground mine engineering.
基金supported by the National Natural Science Foundation of China(Grant No.51974173)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020QD122).
文摘The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified.
基金supported by the National Natural Science Foundation of China(42088101 and 42030605)support from the research project:Towards an Operational Fire Early Warning System for Indonesia(TOFEWSI)+1 种基金The TOFEWSI project was funded from October 2017-October 2021 through the UK’s National Environment Research Council/Newton Fund on behalf of the UK Research&Innovation(NE/P014801/1)(UK Principal InvestigatorAllan Spessa)(https//tofewsi.github.io/)financial support from the Natural Science Foundation of Qinghai(2021-HZ-811)。
文摘In Australia,the proportion of forest area that burns in a typical fire season is less than for other vegetation types.However,the 2019-2020 austral spring-summer was an exception,with over four times the previous maximum area burnt in southeast Australian temperate forests.Temperate forest fires have extensive socio-economic,human health,greenhouse gas emissions,and biodiversity impacts due to high fire intensities.A robust model that identifies driving factors of forest fires and relates impact thresholds to fire activity at regional scales would help land managers and fire-fighting agencies prepare for potentially hazardous fire in Australia.Here,we developed a machine-learning diagnostic model to quantify nonlinear relationships between monthly burnt area and biophysical factors in southeast Australian forests for 2001-2020 on a 0.25°grid based on several biophysical parameters,notably fire weather and vegetation productivity.Our model explained over 80%of the variation in the burnt area.We identified that burnt area dynamics in southeast Australian forest were primarily controlled by extreme fire weather,which mainly linked to fluctuations in the Southern Annular Mode(SAM)and Indian Ocean Dipole(IOD),with a relatively smaller contribution from the central Pacific El Niño Southern Oscillation(ENSO).Our fire diagnostic model and the non-linear relationships between burnt area and environmental covariates can provide useful guidance to decision-makers who manage preparations for an upcoming fire season,and model developers working on improved early warning systems for forest fires.
文摘In this review,advances in the understanding of the controlling factors and physical mechanisms of tropical cyclogenesis(TCG)are summarized from recent(2018–2022)research on TCG,as presented in the Tenth International Workshop on Tropical Cyclones(IWTC-10).Observational,theoretical,and numerical modeling studies published in recent years have advanced our knowledge on the influence of large-scale environmental factors on TCG.Furthermore,studies have shown clearly that appropriate convective coupling with tropical equatorial waves enhances the development chances of TCG.More recently,illuminating research has been carried out on analyzing the mechanisms by which oscillations and teleconnections(El Ni˜no Southern Oscillation(ENSO)in particular)modulate TCG globally,in association with changes in the sea surface temperature(SST).In addition to this,recent research has diligently addressed different aspects of TCG.Multiple studies have reported the applicability of unified theories and physical mechanisms of TCG in different ocean basins.Recently,research has been carried out on TCG under different flow pattern regimes,dry air intrusion,importance of marsupial pouch,genesis of Medicanes,wind shear,convection and vertical structure.Furthermore,studies have discussed the possibility of near equatorial TCG provided that there is enough supply of background vertical vorticity and relatively low vertical wind shear.Progress has been made to understand the role of climate change on global and regional TCG.However,there are still significant gaps which need to be addressed in order to better understand TCG prediction.
基金financial supports from the National Key R&D Program of China (2018YFC0604604)the National Natural Science Foundation of China-Yunnan Joint Fund (U1702252)+1 种基金the Fundamental Research Funds for Central Universities of China (N182506003)the Key Scientific Research Project of Liaoning Province,China (2019JH2/10300051)。
文摘Efficient destruction of cyanide by thermal decomposition with ferric oxide addition was proposed. The mechanism of destruction of sodium cyanide with or without ferric oxide addition under various conditions was examined by XRD, DSC-TG, and chemical analysis technologies. In the absence of ferric oxide, sodium cyanide decomposes at 587.4 ℃ in air and 879.2 ℃ in argon atmosphere. In the presence of ferric oxide, about 60% of sodium cyanide decomposes at 350 ℃ for 30 min in argon, while almost all sodium cyanide decomposes within 30 min in air or O2 with mass ratio of ferric oxide to sodium cyanide of 1:1. The increase of ferric oxide addition, temperature, and heating time facilitates the destruction of sodium cyanide. It is believed that with ferric oxide addition, NaCN reacts with Fe2O3 to form Na4Fe(CN)6, Na2CO3, NaNO2 and Fe3O4 in argon. NaCN decomposes into NaCNO, Na4Fe(CN)6, minor NaNO2, and the formed NaCNO and Na4Fe(CN)6 further decompose into Na2CO3, CO2, N2, FeOx, and minor NOx in air or O2.
基金Project(11272359)supported by the National Natural Science Foundation of China
文摘Homogeneity and heterogeneity are two totally different concepts in nature.At the particle length scale,rocks exhibit strong heterogeneity in their constituents and porosities.When the heterogeneity of porosity obeys the random uniform distribution,both the mean value and the variance of porosities in the heterogeneous porosity field can be used to reflect the overall heterogeneous characteristics of the porosity field.The main purpose of this work is to investigate the effects of porosity heterogeneity on chemical dissolution front instability in fluid-saturated rocks by the computational simulation method.The related computational simulation results have demonstrated that:1) since the propagation speed of a chemical dissolution front is inversely proportional to the difference between the final porosity and the mean value of porosities in the initial porosity field,an increase in the extent of the porosity heterogeneity can cause an increase in the mean value of porosities in the initial porosity field and an increase in the propagation speed of the chemical dissolution front.2) An increase in the variance of porosities in the initial porosity field can cause an increase in the instability probability of the chemical dissolution front in the fluid-saturated rock.3) The greater the mean value of porosities in the initial porosity field,the quicker the irregular morphology of the chemical dissolution front changes in the supercritical chemical dissolution systems.This means that the irregular morphology of a chemical dissolution front grows quicker in a porosity field of heterogeneity than it does in that of homogeneity when the chemical dissolution system is at a supercritical stage.
基金This research was supported by the National Natural Science Foundation of China(41871204,41701627 and 41971255)Fundamental Research Funds for the Central Universities(N172504026,N182502045)。
文摘Introduction:Over the past two decades,China has experienced rapid economic development,which has not only led to a rapid increase in the use of raw materials but has also created environmental problems.This research analyzes the environmental impacts of resource extraction in China at the provincial level,and fully considers the environmental impact of various resources extraction.In addition,it is the first time to quantitatively study the spatial pattern and evolution characteristics of the environmental impacts of China’s resource extraction from multiple perspectives by means of spatial visualization.Outcomes:The results showed that the center of gravity of abiotic depletion potential(ADP)moved northwest,respiratory inorganics(RI)moved southwest and global warming potential(GWP)moved west.The results of the standard deviation ellipse showed that RI and GWP varied over time and space,while ADP showed a discrete trend.In addition,the distribution of the four in the northeast-southwest direction became more prominent.Conclusion:To mitigate the environmental impacts of resource extraction,we recommend that regional governments implement measures to control environmental impacts in the provinces within the distributed ellipse and design targeted policies based on actual conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.42071041 and 41807171)the Outstanding Youth Science Foundation of the National Natural Science Foundation of China(Grant No.51822908)。
文摘Integrated water quantity and quality simulations have become a popular tool in investigations on global water crisis.For integrated and complex models,conventional uncertainty estimations focus on the uncertainties of individual modules,e.g.,module parameters and structures,and do not consider the uncertainties propagated from interconnected modules.Therefore,this study investigated all the uncertainties of integrated water system simulations using the GLUE(i.e.,generalized likelihood uncertainty estimation)method,including uncertainties associated with individual modules,propagated uncertainties associated with interconnected modules,and their combinations.The changes in both acceptability thresholds of GLUE and the uncertainty estimation results were also investigated for different fixed percentages of total number of iterations(100000).Water quantity and quality variables(i.e.,runoff and ammonium nitrogen)were selected for the case study.The results showed that module uncertainty did not affect the runoff simulation performance,but remarkably weakened the water quality responses as the fixed percentage increased during calibration and validation periods.The propagated uncertainty from hydrological modules could not be ignored for water quality simulations,particularly during validation.The combination of module and propagated uncertainties further weakened the water quality simulation performance.The uncertainty intervals became wider owing to an increase in the fixed percentages and introduction of more uncertainty sources.Moreover,the acceptability threshold had a negative nonlinear relationship with the fixed percentage.The fixed percentages(20.0%-30.0%)were proposed as the acceptability thresholds owing to the satisfactory simulation performance and noticeably reduced uncertainty intervals they produced.This study provided methodological foundations for estimating multiple uncertainty sources of integrated water system models.
基金supported by the National Natural Science Foundation of China(41991230)the Joint CAS(Chinese Academy of Sciences)&MPG(Max-Planck-Gesellschaft)Research Project(HZXM20225001MI)the International Partnership Program of the Chinese Academy of Sciences(121311KYSB20170004)。
文摘Drylands cover approximately 41%of the global land surface and provide homes to more than two billion people. Collectively,drylands constitute the largest terrestrial biome on the planet,and despite their low productivity per land area compared to other ecosystems, they have a major impact on the ecological functioning and climate of our planet through carbon storage, albedo, dust production, and water cycling [1].
文摘An abundance of data from seismic and geodetic monitoring has provided new insight into dyke propagation and emplacement mechanisms.These studies show that faulting and fracturing is part of the magma
基金the CSIRO Low Emissions Technologies Program for the support of this studythe financial support from the Australian Research Council(ARC)for the Future Fellowship(FT130101337)+4 种基金QUT core funding(QUT/322120-0301/07)supported by NSF MRI(1428992)U.S.-Egypt Science and Technology(S&T)Joint FundSDBoR R&D ProgramEDA University Center Program(ED18DEN3030025)。
文摘Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.
基金Supported by the National Key Research and Development Program of China (2018YFC1506501, 2018YFA0605503, and2016YFB0501502)Special Program of Gaofen Satellites (04-Y30B01-9001-18/20-3-1)National Natural Science Foundation of China (41871230 and 41871231)。
文摘High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estimate FVC at a 30-m/15-day resolution over China by taking advantage of the spatial and temporal information from different types of sensors: the 30-m resolution sensor on the Chinese environment satellite(HJ-1) and the 1-km Moderate Resolution Imaging Spectroradiometer(MODIS). The algorithm was implemented for each main vegetation class and each land cover type over China. First, the high spatial resolution and high temporal frequency normalized difference vegetation index(NDVI) was acquired by using the continuous correction(CC) data assimilation method. Then, FVC was generated with a nonlinear pixel unmixing model. Model coefficients were obtained by statistical analysis of the MODIS NDVI. The proposed method was evaluated based on in situ FVC measurements and a global FVC product(GEOV1 FVC). Direct validation using in situ measurements at 97 sampling plots per half month in 2010 showed that the annual mean errors(MEs) of forest, cropland, and grassland were-0.025, 0.133, and 0.160, respectively, indicating that the FVCs derived from the proposed algorithm were consistent with ground measurements [R2 = 0.809,root-mean-square deviation(RMSD) = 0.065]. An intercomparison between the proposed FVC and GEOV1 FVC demonstrated that the two products had good spatial–temporal consistency and similar magnitude(RMSD approximates 0.1). Overall, the approach provides a new operational way to estimate high spatial resolution and high temporal frequency FVC from multiple remote sensing datasets.
