Analyzing the sources of nitrogen and phosphorus pollution in atmospheric deposition is crucial for protecting the surfacewater environment in vulnerable areas.This study focused on the Dahekou Reservoir,Shayuan Distr...Analyzing the sources of nitrogen and phosphorus pollution in atmospheric deposition is crucial for protecting the surfacewater environment in vulnerable areas.This study focused on the Dahekou Reservoir,Shayuan District,Xilin Gol League,Inner Mongolia,China.It established 12 monitoring sites,conducted one-year monitoring,and collected 144 samples.The concentrations of nitrogen,phosphorus,and water-soluble ions in atmospheric wet sedimentation were measured.This study identified atmospheric precipitation types,revealed seasonal variations in nitrogen and phosphorus concentrations,assessed the contribution of atmosphericwet sedimentation to reservoirwater quality.Utilizing the airmass backward trajectory(HYSPLIT)model and PMF model,themain pollution sources were analyzed.The results were as follows.1)During the observation period,the atmospheric precipitation types were nitric acid rain in spring,sulfuric acid rain in winter,and mixed acid rain in summer and autumn.2)The monthly concentrations of nitrogen and phosphorus of various forms varied significantly,with NH_(4)^(+)-N peaking in spring,NO_(3)^(-)-N and DOP in autumn,and DIP and DON in summer.Annual pollution loads of atmospheric nitrogen and phosphorus precipitation into the reservoir were 35.77 and 4.17 t/a,respectively,severely impacting reservoir water quality.3)Precipitation was negatively correlated with TN concentration,particularly with the NO_(3)^(-)-N/TN ratio,and positively correlated with TP and DIP concen-trations.4)The analysis of pollution sources indicated that the sources of atmospheric nitrogen and phosphorus wet deposition pollution in the study area included agricultural,anthropogenic,dust,and coal sources,with contribution rates of 32.4%,25.6%,21.0%,and 21.0%,respectively.展开更多
The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about...The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about the effects of microtopography on particle size characteristics(PSC)of eroded sediments from the bare slopes of zokor mounds during different rainfall events.In this study,we analyzed the relationship of microtopographic features derived from laser point cloud data and PSC of eroded sediments at six simulated rainfall intensities(all lasting 60 min).The effects of microtopography on PSC of eroded sediments were studied via partial least squares regression(PLSR)and structural equation modeling(SEM).The results showed that:(1)15-20 minutes from the beginning of rainfall was the sensitive period of soil loss from the slopes,and the function relationship between the rate of sediment and runoff and rainfall intensity can better predict the development trend of soil erosion;(2)Intense erosion occurred mainly in the upper half of the zokor mound,while deposition was mainly limited to its lower half.It is suggested that diminished plateau zokor activity intensity can effectively prevent and control soil erosion;(3)The PSC of eroded sediment is dominated by silt,followed by sand,with clay being the least abundant,and the eroded sediments with a particle size of 10-20μm were sensitive and highly susceptible to rainfall erosion.This finding facilitates the understanding of the formation process of surface geomorphology and the mechanism of soil erosion;(4)The PLSR model indicates that microtopography has an extensive influence on eroded sediments during hydraulic erosion,and the SEM analysis results further confirm that the fractal dimension was the best parameter to represent the PSC of eroded sediments,whereas surface cutting degree was the dominant factor controlling the PSC of eroded sediments.These findings are crucial for predicting soil erosion in the Yellow River source area and provide a new perspective for understanding soil erosion mechanisms in alpine meadow ecosystems.展开更多
[Objective] The paper was to analyze the quality of flux observation data of rubber plantation.[Method]Based on the FSAM model,footprint and flux source area were analyzed according to the continuous flux measurement ...[Objective] The paper was to analyze the quality of flux observation data of rubber plantation.[Method]Based on the FSAM model,footprint and flux source area were analyzed according to the continuous flux measurement with the open-path eddy covariance system on the 50 m tower of Danzhou Key Field Station of Observation and Research for Tropical Agricultural Resources and Environments,Ministry of Agriculture from Jan 1 to Jun 30,2010.[Result] Under unstable stratification,source areas were smaller than those under stable conditions,and source areas in the dormant season were larger than those in the growing season at the same level.In the main wind direction 130°-270°,the upwind range of source areas was in the magnitude of 100-758 m and vertical upwind range was-251-251 m at 80% level under unstable stratification in the growing season,and they were some large than those under the unstable stratification in the dormant season.The source areas of the upwind and vertical upwind ranges were 173-1 858,-534-534 m especially under stable stratification in the growing season,and they were smaller than those under stable stratification in the dormant season.In the other wind directions of 0°-130° and 270°-360°,the ranges were similar to those of the growing season in the prevailing wind direction under the same atmospheric conditions.[Conclusion] The study would lay a foundation for the future flux calculation and analysis.展开更多
Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the T...Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the Tanag hydrological station)on the northeastern Qinghai-Tibet Plateau,West China.How and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River streamflow.Results show that permafrost degradation may have released appreciable meltwater for recharging groundwater.The potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at Huangheyan.Seasonal/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the SAYR.Improved hydraulic connectivity is expected to occur during and after certain degrees of permafrost degradation.Direct impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice meltwater.Enhanced evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.展开更多
Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrologica...Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrological and meteorological variables over the source area of the Yellow River （SAYR） from 1961 to 2,012 and the future climate scenarios in the region during 2006-2100 based on the CMIP5 projection data. It recognizes the significant charac-teristics of the recent climate change in the SAYR and predicts the change trend of future flow in the region. It is found that （1） The climate in the SAYR has experienced a significant warm-wet change since the early 2000s, which is very different from the antecedent warm-dry trend since the late 1980s; （2） The warm-wet trend in the northwestern SAYR （the headwater area of the Yellow River （HAYR）, is more obvious than that in the whole SAYR; （3） With pre- cipitation increase, the runoff in the region also experienced an increasing process since 2006. The runoff variations in the region are sensitive to the changes of precipitation, PET and maximum air temperature, but not very sensitive to changes in mean and minimum air temperatures; （4） Based on the CMIP5 projection data, the warm-wet climate trend in SAYR are likely to continue until 2049 if considering three different （i.e. RCP2.6, RCP4.5 and RCP8.5） greenhouse gas emission scenarios, and the precipitation in SAYR will not be less than the current level before 2100; however, it is estimated that the recent flow increase in the SAYR is likely to be the decadal change and it will at most continue until the 2020s; （5） The inter-annual variations of the East Asian winter monsoon are found to be closely related to the variations of annual precipitation in the region. Meanwhile, the increased precipitation as well as the increase of potential evapotranspiration （PET） being far less than that of precipitation in the recent period are the main climate causes for the flow increase in the region.展开更多
Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then t...Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then the co-relationship between genus species of soil dematiaceous hyphomycetes and ecosystem-types was analyzed. The results show that the amount and species distribution of soil dematiaceous hyphomycetes had an obvious variability in different ecosystem-types, and that the dominant genus species varied in the eight ecosystem-types studied, with Cladosporium being the dominant genus in seven of the eight ecosystem-types except wetland. The index of species diversity varied in different ecosystem-types. The niche breadth analysis showed that Cladosporium had the highest niche breadth and distributed in all ecosystem-types, while the genera with a narrow niche breadth distributed only in a few ecosystem-types. The results of niche overlap index analysis indicated that Stachybotrys and Torula, Doratomyces and Scolecobasidium, Cladosporium and Chrysosporium had a higher niche overlap, whereas Arthrinium and Gliomastix, Phialophora and Doratomyces, Oidiodendron and Ulocladium had no niche overlap.展开更多
This study attempts to identify the dominant transport pathways,potential source areas,and their seasonal variation at sites with high inorganic nitrogen(IN)wet deposition flux in southern China.This is a long-term st...This study attempts to identify the dominant transport pathways,potential source areas,and their seasonal variation at sites with high inorganic nitrogen(IN)wet deposition flux in southern China.This is a long-term study(2010-2017)based on continuous deposition measurements at the Guangzhou urban site(GZ)and the Dinghushan Natural Reserve site(DHS)located in the Pearl River Delta(PRD)region.A dataset on monthly IN concentration in precipitation and wet deposition flux were provided.The average annual fluxes measured at both sites(GZ:33.04±9.52,DHS:20.52±10.22 kg N/(ha·year))were higher,while the ratios of reduced to oxidized N(GZ:1.19±0.77,DHS:1.25±0.84)were lower compared with the national mean level and the previous reported level throughout the PRD region.The dominant pathways were not always consistent with the highest proportional trajectory clusters.The transport pathways contributing most of deposition were identified in the north and northnortheast in the dry season and in the east-southeast,east,and south-southwest in the wet season.A weighted potential source contribution function(WPSCF)value>0.3 was determined reasonably to define the potential source area.Emission within the PRD region contributed the majority(≥95%at both sites)of the IN deposition in the wet season,while the contribution outside the region increased significantly in the dry season(GZ:27.86%,DHS:95.26%).Our results could help create more effective policy to control precursor emissions for IN fluxes,enabling reduction of the ecological risks due to excessive nitrogen.展开更多
Based on one-year observation,the concentration,sources,and potential source areas of volatile organic compounds(VOCs)were comprehensively analyzed to investigate the pollution characteristics of ambient VOCs in Haiko...Based on one-year observation,the concentration,sources,and potential source areas of volatile organic compounds(VOCs)were comprehensively analyzed to investigate the pollution characteristics of ambient VOCs in Haikou,China.The results showed that the annual average concentration of total VOCs(TVOCs)was 11.4 ppb V,and the composition was dominated by alkanes(8.2 ppb V,71.4%)and alkenes(1.3 ppb V,20.5%).The diurnal variation in the concentration of dominant VOC species showed a distinct bimodal distribution with peaks in the morning and evening.The greatest contribution to ozone formation potential(OFP)was made by alkenes(51.6%),followed by alkanes(27.2%).The concentrations of VOCs and nitrogen dioxide(NO_(2))in spring and summer were low,and it was difficult to generate high ozone(O_(3))concentrations through photochemical reactions.The significant increase in O_(3)concentrations in autumn and winter was mainly related to the transmission of pollutants from the northeast.Traffic sources(40.1%),industrial sources(19.4%),combustion sources(18.6%),solvent usage sources(15.5%)and plant sources(6.4%)were identified as major sources of VOCs through the positive matrix factorization(PMF)model.The southeastern coastal areas of China were identified as major potential source areas of VOCs through the potential source contribution function(PSCF)and concentration-weighted trajectory(CWT)models.Overall,the concentration of ambient VOCs in Haikou was strongly influenced by traffic sources and long-distance transport,and the control of VOCs emitted from vehicles should be strengthened to reduce the active species of ambient VOCs in Haikou,thereby reducing the generation of O_(3).展开更多
The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are r...The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are recognized as two types. One was found in sandy gravel beds of the second terrace of the Yellow River. This ice-wedge pseudomorph is characterized by higher ratio of breadth/depth, and are 1-1.4 m wide and about 1 m deep. The bottom border of the ice-wedge pseudomorph is round arc in section. Another discovered in the pedestal of the second terrace has lower ratio of width/depth, and is o.3-1.0 m wide and 1-2 m deep. Its bottom border is sharp. Based on the TL dating, the former was formed at the middleHolocene （5.69±0.43 ka BP and 5.43±0.41 ka BP）, that is, the Megathermal, and the latter was formed at the late Last Glacial Maximum （13.49±1.43 ka BP）. Additionally, the thawing-freezing folders discovered in the late Late Pleistocene proluvium are 39.83±3.84 ka BP in age. The study on the ice-wedge pseudomorphs showed that the air temperature was lowered by up to 6-7℃ in the source area of the Yellow River when the ice-wedge pseudomorphs and thawing-freezing folds developed.展开更多
Protection planning is made for rural centralized drinking water source areas according to current situations of rural drinking water and existing problems of centralized drinking water source areas in Chongqing,and i...Protection planning is made for rural centralized drinking water source areas according to current situations of rural drinking water and existing problems of centralized drinking water source areas in Chongqing,and in combination with survey,analysis and evaluation of urban-rural drinking water source areas in whole city.There are engineering measures and non-engineering measures,to guarantee drinking water security of rural residents,improve rural ecological environment,realize sustainable use of water resource,and promote sustainable development of society.Engineering measures include conservation and protection of water resource,ecological restoration,isolation,and comprehensive control of pointsource and area-source pollution.Non-engineering measures include construction of monitoring system for drinking water source area,construction of security information system for rural centralized drinking water source area,and construction of emergency mechanism for water pollution accidents in rural water source areas.展开更多
Nitrogen(N)present in drinking water as dissolved nitrates can directly affect people’s health,making it important to control N pollution in water source areas.N pollution caused by agricultural fertilizers can be co...Nitrogen(N)present in drinking water as dissolved nitrates can directly affect people’s health,making it important to control N pollution in water source areas.N pollution caused by agricultural fertilizers can be controlled by reducing the amount of fertilizer applied,but pollution caused by soil and water erosion in hilly areas can only be controlled by conservation forests.The catchment area around Fushi Reservoir was selected as a test site and mechanisms of N loss from a vertical spatial perspective through field observations were determined.The main N losses occurred from June to September,accounting for 85.9-95.9%of the annual loss,with the losses in June and July accounting for 46.0%of the total,and in August and September for 41.9%.The N leakage from the water source area was effectively reduced by 38.2%through the optimization of the stand structure of the conservation forests.Establishing well-structured forests for water conservation is crucial to ensure the security of drinking water.This preliminary research lays the foundation for revealing then loss mechanisms in water source areas and improving the control of non-point source pollution in these areas.展开更多
In this study,in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture prod ucts from NASA(National Aeronautics and Space Administration),JAXA(Japanese Aerospace Exploration A...In this study,in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture prod ucts from NASA(National Aeronautics and Space Administration),JAXA(Japanese Aerospace Exploration Agency)and VUA(Vrije University Amsterdam and NASA)over Maqu County,Source Area of the Yellow River(SAYR),China.Re sults show that the VUA soil moisture product performs the best among the three AMSR-E soil moisture products in the study area,with a minimum RMSE(root mean square error)of 0.08(0.10)m3/m3 and smallest absolute error of 0.07(0.08)m3/m3 at the grassland area with ascending(descending)data.Therefore,the VUA soil moisture product is used to describe the spatial variation of soil moisture during the 2010 growing season over SAYR.The VUA soil moisture product shows that soil moisture presents a declining trend from east south(0.42 m3/m3)to west north(0.23 m3/m3),with good agreement with a general precipitation distribution.The center of SAYR presents extreme wetness(0.60 m3/m3)dur ing the whole study period,especially in July,while the head of SAYR presents a high level soil moisture(0.23 m3/m3)in July,August and September.展开更多
We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China ...We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.展开更多
Based on the dynamic analysis and research of pollution risk of groundwater sources,this paper creates the dynamic assessment method of pollution risk of groundwater source area under the theory of"source-pathway...Based on the dynamic analysis and research of pollution risk of groundwater sources,this paper creates the dynamic assessment method of pollution risk of groundwater source area under the theory of"source-pathway-receptor",and applies this method to one typical fissure karst groundwater source area in northern China.Following the 30-year petroleum pollutant migration simulation and pollution risk assessment of groundwater source area,this study finds that the very high risk zone is mainly located in Q Petrochemical Company and the surrounding area and the area adjacent to River Z.Within this period of thirty years,the pollution risk of groundwater source area has showed a dynamic trend that features an inverted"V"shape.The ratio of very high risk zone to the total area will be 18.1%,17.47%and 16.62%during the tenth year,the twentieth year and the thirtieth year separately,and will reach the highest level of 19.45%during the fifteenth year.Meanwhile,the vertical migration distance of pollutant centre concentration changed from the surface soil at the outset to the deepest point of about 250 meters underground during the tenth year.The results of this risk assessment indicate the dynamic feature of pollution risk.The dilution,degradation and migration of petroleum pollutants in groundwater system contribute to an ultimate decline in pollution risk.展开更多
The Shitoukoumen Reservoir is one of main drinking water source areas in Changchun City,and there is a contradiction between the protection and the economic development of water source areas. In this paper,the primary...The Shitoukoumen Reservoir is one of main drinking water source areas in Changchun City,and there is a contradiction between the protection and the economic development of water source areas. In this paper,the primary and secondary reserves in drinking water source area of the Shitoukoumen Reservoir are taken as research objects. Based on the theory of ecological compensation,the ecological compensation standard is accounted and determined from different perspectives,and the suggestion of the phased ecological compensation in water source areas is proposed.展开更多
The characteristics of seismogenic structures are an important basis for delineating the potential seismic source areas and determining the annual occurrence rate of earthquakes. The potential seismic source area does...The characteristics of seismogenic structures are an important basis for delineating the potential seismic source areas and determining the annual occurrence rate of earthquakes. The potential seismic source area does not only have the intension that “this area has the possibility for destructive earthquakes to occur in the future" but also means that earthquakes of high magnitude interval have the characteristics of similar recurrence. When determining the seismic activity parameters of a statistical unit, some active tectonic blocks in the unit may have different background earthquakes. In order to better reflect the heterogeneity in space of seismic activities, it is necessary to divide the potential seismic source areas into three orders. By analyzing the recurrence characteristics of earthquakes of high magnitude interval in the potential source area and calculating the occurrence probability of earthquakes of high magnitude interval in the potential seismic source area in the time window for prediction, the average annual occurrence rate of earthquakes can be obtained by the method of probability equivalent conversion in the time window for prediction. This would be helpful for considering the recurrence characteristics of strong earthquakes in potential source areas within the framework of seismic risk analysis of China. Besides, the insufficient frequency of characteristic earthquakes of the next high magnitude interval in the potential source area and the heterogeneity of strong earthquakes on seismogenic structures are analyzed to see their application in seismic risk analysis.展开更多
This study tracked the characteristics of atmospheric wet deposition of the toxic element arsenic(As)at both urban(Guangzhou(GZ))and forested(Dinghushan Natural Reserve(DHS))sites within the Pearl River Delta(PRD)regi...This study tracked the characteristics of atmospheric wet deposition of the toxic element arsenic(As)at both urban(Guangzhou(GZ))and forested(Dinghushan Natural Reserve(DHS))sites within the Pearl River Delta(PRD)region between 2016 and 2019,examining its correlation with rainfall patterns.Additionally,by employing backward trajectory analysis and the potential source contribution function(PSCF)in conjunction with pertinent emission inventories,we pinpointed the main pathways of atmospheric arsenic transport and evaluated the emission contributions from priority source areas.The study revealed that the atmospheric arsenic wet deposition fluxes at the GZ and DHS sites exhibited a trend of increase followed by a decrease over the four-year period.Wet season deposition fluxes were more than triple those of the dry season,with urban site showing a difference of over four times.Notably,wet season As deposition at both sites was predominantly affected by heavy rainfall from marine air masses,constituting 31%of the total deposition.The predominant trajectory directions contributing to arsenic deposition at GZ and DHS were northeast(55%)and south(53%),respectively.The primary source areas for both sites were largely outside the PRD region,with the GZ site having 80%to 95%of its source area in the non-PRD region,compared to 69%to 88%at the DHS site.Furthermore,non-PRD areas contributed approximately 65%to arsenic emissions for both sites,with the industrial sector being the dominant emission source,exceeding 97%of the total emissions.展开更多
As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and biogeochemistry.In the Sources Area of the Yellow River(SAYR),pe...As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and biogeochemistry.In the Sources Area of the Yellow River(SAYR),permafrost degradation has accelerated since the 1980s,and numerous thermokarst lakes have been discovered.In this paper,we use Sentinel-2 images to extract thermokarst lake boundaries and perform a regional-scale study on their geometry across the permafrost region in the SAYR.We also explored the spatiotemporal variations and potential drivers from the perspectives of the permafrost,climate,terrain and vegetation conditions.The results showed that there were 47,518 thermokarst lakes in 2021 with a total area of 190.22×106 m^(2),with an average size of 4,003.3 m^(2).The 44,928 ponds(≤10,000 m^(2))predominated the whole lake number(94.1%)but contributed to a small portion of the total lake area(28.8%).With 2,590 features(5.9%),small-sized(10,000 to 100,000 m^(2))and large-sized lakes(>100,000 m^(2))constituted up to 71.2%of the total lake area.Thermokarst lakes developed more significantly in warm permafrost regions than in cold permafrost areas;74.1%of lakes with a total area of 119.6×106 m^(2)(62.9%),were distributed in warm permafrost regions.Most thermokarst lakes were likely to develop within the elevation range of 4,500~4,800 m,on flat terrain(slope<10°),on SE and S aspects and in alpine meadow areas.The thermokarst lakes in the study region experienced significant shrinkage between 1990 and 2021,characterized by obvious lake drainage;the lake numbers decreased by 5418(56.1%),with a decreasing area of 58.63×106 m^(2)(49.0%).This shrinkage of the thermokarst lake area was attributable mainly to the intensified degradation of rich-ice permafrost thawing arising from continued climate warming,despite the wetting climatic trend.展开更多
Critical source areas （CSAs）, characterized by severe soil erosion and high sediment yield, are considered to have a high priority for conservation. How to identify CSAs and assess the effectiveness of conservation ...Critical source areas （CSAs）, characterized by severe soil erosion and high sediment yield, are considered to have a high priority for conservation. How to identify CSAs and assess the effectiveness of conservation practices is a key issue in site-specific watershed management. The Soil and Water Assessment Tool （SWAT） model is a useful tool for site-specific conservation practices design and several studies have attempted to identify CSAs based on watershed models. However, limited research has reported about the effectiveness of conservation practices targeting CSAs. The aim of this study was to assess the effectiveness of conservation pracrices targeted on CSAs using the SWAT model. CSA was firstly identified based on the 4-year average yearly erosion of each HRU. Appropriate soil conservation practices were then designed for the CSAs. A scenario with conservation practices for the whole watershed was also established as the contrasting counter parts scheme and then compared to the outcome of CSA-targeted conservation practices. The result shows that SWAT can accurately simulate sediment yield in the study area. CSAs were mainly located in slope farmland areas and steep gullies, coinciding with the distribution of land use and slope. The identified CSA covered 20% of the HRUs and contributed on average 44% of sediment yield. Conservation practices targeting CSAs had higher sediment reduction effectiveness （24 115 t km-2 y-1） than conservation practice covering the whole watershed （20 290 t km-2 y-1）. Thus conservation practices targeting CSAs are more effective than broad conservation practices. We conclude that soil conservation practices focusing on CSAs do increase sediment reduction effectiveness. Targeting the placement of soil conservation practices based on the CSAs concept will assist water quality control in watersheds.展开更多
Jurassic rocks are abundantly developed in the source area of the Yangtze River,South Qinghai,with the greatest thickness of 6311 m,including five stratigraphic units:Qoimaco Formation,Buqu Formation,Xiali Formation,S...Jurassic rocks are abundantly developed in the source area of the Yangtze River,South Qinghai,with the greatest thickness of 6311 m,including five stratigraphic units:Qoimaco Formation,Buqu Formation,Xiali Formation,Suowa Formation,and Xueshan Formation.Based on sufficient fossils of bivalves,ammonites,and brachiopods,the major part of these formations is ascribed to the Middle Jurassic Bathonian to Callovian.No diagnostic fossils have been found from the Lower Qoimaco Formation or Upper Xueshan Formation,which could possibly contain in part Bajocian and Oxfordian taxa respectively.展开更多
基金supported by Inner Mongolia Autonomous Region Department of Education Science and Technology Talent Project(No.NJYT22040)Inner Mongolia Agricultural University Young Teachers'Scientific Research Ability Promotion Project(No.BR220102)+4 种基金the National Natural Science Foundation of China(No.52260029)the National Key R&D Program(No.2019YFC0409204)Inner Mongolia Natural Science Foundation(No.2021MS04013)the Science and Technology Project of Inner Mongolia Autonomous Region(No.2023YFHH0060)Inner Mongolia AutonomousRegion Science and Technology Leading TalentTeam(No.2022LJRC0007).
文摘Analyzing the sources of nitrogen and phosphorus pollution in atmospheric deposition is crucial for protecting the surfacewater environment in vulnerable areas.This study focused on the Dahekou Reservoir,Shayuan District,Xilin Gol League,Inner Mongolia,China.It established 12 monitoring sites,conducted one-year monitoring,and collected 144 samples.The concentrations of nitrogen,phosphorus,and water-soluble ions in atmospheric wet sedimentation were measured.This study identified atmospheric precipitation types,revealed seasonal variations in nitrogen and phosphorus concentrations,assessed the contribution of atmosphericwet sedimentation to reservoirwater quality.Utilizing the airmass backward trajectory(HYSPLIT)model and PMF model,themain pollution sources were analyzed.The results were as follows.1)During the observation period,the atmospheric precipitation types were nitric acid rain in spring,sulfuric acid rain in winter,and mixed acid rain in summer and autumn.2)The monthly concentrations of nitrogen and phosphorus of various forms varied significantly,with NH_(4)^(+)-N peaking in spring,NO_(3)^(-)-N and DOP in autumn,and DIP and DON in summer.Annual pollution loads of atmospheric nitrogen and phosphorus precipitation into the reservoir were 35.77 and 4.17 t/a,respectively,severely impacting reservoir water quality.3)Precipitation was negatively correlated with TN concentration,particularly with the NO_(3)^(-)-N/TN ratio,and positively correlated with TP and DIP concen-trations.4)The analysis of pollution sources indicated that the sources of atmospheric nitrogen and phosphorus wet deposition pollution in the study area included agricultural,anthropogenic,dust,and coal sources,with contribution rates of 32.4%,25.6%,21.0%,and 21.0%,respectively.
基金financially supported by the Qinghai University Graduate Student Research and Practice Innovation Project(2025-GPKY-12)Basic Research Project of Qinghai Provincial Science and Technology Department(2021-ZJ-701)+1 种基金National Natural Science Foundation of China(U23A20159,42161068)the 111 Project of China(D18013)。
文摘The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about the effects of microtopography on particle size characteristics(PSC)of eroded sediments from the bare slopes of zokor mounds during different rainfall events.In this study,we analyzed the relationship of microtopographic features derived from laser point cloud data and PSC of eroded sediments at six simulated rainfall intensities(all lasting 60 min).The effects of microtopography on PSC of eroded sediments were studied via partial least squares regression(PLSR)and structural equation modeling(SEM).The results showed that:(1)15-20 minutes from the beginning of rainfall was the sensitive period of soil loss from the slopes,and the function relationship between the rate of sediment and runoff and rainfall intensity can better predict the development trend of soil erosion;(2)Intense erosion occurred mainly in the upper half of the zokor mound,while deposition was mainly limited to its lower half.It is suggested that diminished plateau zokor activity intensity can effectively prevent and control soil erosion;(3)The PSC of eroded sediment is dominated by silt,followed by sand,with clay being the least abundant,and the eroded sediments with a particle size of 10-20μm were sensitive and highly susceptible to rainfall erosion.This finding facilitates the understanding of the formation process of surface geomorphology and the mechanism of soil erosion;(4)The PLSR model indicates that microtopography has an extensive influence on eroded sediments during hydraulic erosion,and the SEM analysis results further confirm that the fractal dimension was the best parameter to represent the PSC of eroded sediments,whereas surface cutting degree was the dominant factor controlling the PSC of eroded sediments.These findings are crucial for predicting soil erosion in the Yellow River source area and provide a new perspective for understanding soil erosion mechanisms in alpine meadow ecosystems.
基金Supported by the Fundamental Research Funds for Rubber Research Institute,CATAS (1630022011013 )Hainan Natural Science Foundation (807045)Running Costs of Danzhou Key Field Station of Observation and Research for Tropical Agricultural Resources and Environments,Ministry of Agriculture~~
文摘[Objective] The paper was to analyze the quality of flux observation data of rubber plantation.[Method]Based on the FSAM model,footprint and flux source area were analyzed according to the continuous flux measurement with the open-path eddy covariance system on the 50 m tower of Danzhou Key Field Station of Observation and Research for Tropical Agricultural Resources and Environments,Ministry of Agriculture from Jan 1 to Jun 30,2010.[Result] Under unstable stratification,source areas were smaller than those under stable conditions,and source areas in the dormant season were larger than those in the growing season at the same level.In the main wind direction 130°-270°,the upwind range of source areas was in the magnitude of 100-758 m and vertical upwind range was-251-251 m at 80% level under unstable stratification in the growing season,and they were some large than those under the unstable stratification in the dormant season.The source areas of the upwind and vertical upwind ranges were 173-1 858,-534-534 m especially under stable stratification in the growing season,and they were smaller than those under stable stratification in the dormant season.In the other wind directions of 0°-130° and 270°-360°,the ranges were similar to those of the growing season in the prevailing wind direction under the same atmospheric conditions.[Conclusion] The study would lay a foundation for the future flux calculation and analysis.
基金the Chinese Academy of Sciences Strategic Priority Research Program(XDA20100103)Ministry of Science and Technology of China Key R&D Program(2017YFC0405704)CAS Overseas Professorships of Victor F Bense and Sergey S Marchenko at the former Cold and Arid Regions Environmental and Engineering Research Institute(now renamed to Northwest Institute of Eco-Environment and Resources),CAS during 2013-2016.
文摘Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the Tanag hydrological station)on the northeastern Qinghai-Tibet Plateau,West China.How and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River streamflow.Results show that permafrost degradation may have released appreciable meltwater for recharging groundwater.The potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at Huangheyan.Seasonal/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the SAYR.Improved hydraulic connectivity is expected to occur during and after certain degrees of permafrost degradation.Direct impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice meltwater.Enhanced evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.
基金The Key Deployment Project of the Chinese Academy of Sciences, No.Y322G73001 National Natural Science Foundation of China, No.91225302, No.91437217, No.41375022, No.41175027 Acknowledgments The TRMM data are provided by the NASA/Goddard Space Flight Center＇s Mesoscale Atmospheric Processes Laboratory and PPS, which develop and compute the TMPA as a contribution to TRMM. We acknowledge computing resources and time on the Supercomputing Center of Cold and Arid Region Environment and Engineering Research Institute of Chinese Academy of Sciences. We also acknowledge National Climate Center of China for collecting, analyzing and providing the data of the World Climate Research Programme＇s （WCRP＇s） the Fifth Phase of the Coupled Model Intercomparison Project （CMIP5）.
文摘Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrological and meteorological variables over the source area of the Yellow River （SAYR） from 1961 to 2,012 and the future climate scenarios in the region during 2006-2100 based on the CMIP5 projection data. It recognizes the significant charac-teristics of the recent climate change in the SAYR and predicts the change trend of future flow in the region. It is found that （1） The climate in the SAYR has experienced a significant warm-wet change since the early 2000s, which is very different from the antecedent warm-dry trend since the late 1980s; （2） The warm-wet trend in the northwestern SAYR （the headwater area of the Yellow River （HAYR）, is more obvious than that in the whole SAYR; （3） With pre- cipitation increase, the runoff in the region also experienced an increasing process since 2006. The runoff variations in the region are sensitive to the changes of precipitation, PET and maximum air temperature, but not very sensitive to changes in mean and minimum air temperatures; （4） Based on the CMIP5 projection data, the warm-wet climate trend in SAYR are likely to continue until 2049 if considering three different （i.e. RCP2.6, RCP4.5 and RCP8.5） greenhouse gas emission scenarios, and the precipitation in SAYR will not be less than the current level before 2100; however, it is estimated that the recent flow increase in the SAYR is likely to be the decadal change and it will at most continue until the 2020s; （5） The inter-annual variations of the East Asian winter monsoon are found to be closely related to the variations of annual precipitation in the region. Meanwhile, the increased precipitation as well as the increase of potential evapotranspiration （PET） being far less than that of precipitation in the recent period are the main climate causes for the flow increase in the region.
基金Project (No. 30670014) supported by the National Natural Science Foundation of China
文摘Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then the co-relationship between genus species of soil dematiaceous hyphomycetes and ecosystem-types was analyzed. The results show that the amount and species distribution of soil dematiaceous hyphomycetes had an obvious variability in different ecosystem-types, and that the dominant genus species varied in the eight ecosystem-types studied, with Cladosporium being the dominant genus in seven of the eight ecosystem-types except wetland. The index of species diversity varied in different ecosystem-types. The niche breadth analysis showed that Cladosporium had the highest niche breadth and distributed in all ecosystem-types, while the genera with a narrow niche breadth distributed only in a few ecosystem-types. The results of niche overlap index analysis indicated that Stachybotrys and Torula, Doratomyces and Scolecobasidium, Cladosporium and Chrysosporium had a higher niche overlap, whereas Arthrinium and Gliomastix, Phialophora and Doratomyces, Oidiodendron and Ulocladium had no niche overlap.
基金supported by National Key Research and Development Plan(No.2017YFC0210100)the National Natural Science Foundation of China(Nos.41905086,41905107,42077205,41425020)+4 种基金the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province(No.2019B121205004)the Natural Science Foundation of Guangdong Province(No.2019A1515011291)the China Postdoctoral Science Foundation(No.2020M683174)the Air Quip(High resolution Air Quality Information for Policy)Project funded by the Research Council of Norway,the Collaborative Innovation Center of Climate Change,Jiangsu province,China,the high-performance computing platform of Jinan University,the Mt.Dinghu Forest Ecosystem Research Station,Chinese Academy of Sciences(CAS)the Comprehensive Observation and Study Site of Urban Meteorology and Environment,Sun Yat-sen University,and the Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(No.2020B1212060025)
文摘This study attempts to identify the dominant transport pathways,potential source areas,and their seasonal variation at sites with high inorganic nitrogen(IN)wet deposition flux in southern China.This is a long-term study(2010-2017)based on continuous deposition measurements at the Guangzhou urban site(GZ)and the Dinghushan Natural Reserve site(DHS)located in the Pearl River Delta(PRD)region.A dataset on monthly IN concentration in precipitation and wet deposition flux were provided.The average annual fluxes measured at both sites(GZ:33.04±9.52,DHS:20.52±10.22 kg N/(ha·year))were higher,while the ratios of reduced to oxidized N(GZ:1.19±0.77,DHS:1.25±0.84)were lower compared with the national mean level and the previous reported level throughout the PRD region.The dominant pathways were not always consistent with the highest proportional trajectory clusters.The transport pathways contributing most of deposition were identified in the north and northnortheast in the dry season and in the east-southeast,east,and south-southwest in the wet season.A weighted potential source contribution function(WPSCF)value>0.3 was determined reasonably to define the potential source area.Emission within the PRD region contributed the majority(≥95%at both sites)of the IN deposition in the wet season,while the contribution outside the region increased significantly in the dry season(GZ:27.86%,DHS:95.26%).Our results could help create more effective policy to control precursor emissions for IN fluxes,enabling reduction of the ecological risks due to excessive nitrogen.
基金supported by the Major Program of Science and Technology of Hainan Province,China(No.ZDKJ202007)the Special Foundation of Government Financial of Hainan Province,China(No.ZC2018-196)the Youth Innovation Foundation of Hainan Research Academy of Environmental Sciences,China(No.QNCX2021002)。
文摘Based on one-year observation,the concentration,sources,and potential source areas of volatile organic compounds(VOCs)were comprehensively analyzed to investigate the pollution characteristics of ambient VOCs in Haikou,China.The results showed that the annual average concentration of total VOCs(TVOCs)was 11.4 ppb V,and the composition was dominated by alkanes(8.2 ppb V,71.4%)and alkenes(1.3 ppb V,20.5%).The diurnal variation in the concentration of dominant VOC species showed a distinct bimodal distribution with peaks in the morning and evening.The greatest contribution to ozone formation potential(OFP)was made by alkenes(51.6%),followed by alkanes(27.2%).The concentrations of VOCs and nitrogen dioxide(NO_(2))in spring and summer were low,and it was difficult to generate high ozone(O_(3))concentrations through photochemical reactions.The significant increase in O_(3)concentrations in autumn and winter was mainly related to the transmission of pollutants from the northeast.Traffic sources(40.1%),industrial sources(19.4%),combustion sources(18.6%),solvent usage sources(15.5%)and plant sources(6.4%)were identified as major sources of VOCs through the positive matrix factorization(PMF)model.The southeastern coastal areas of China were identified as major potential source areas of VOCs through the potential source contribution function(PSCF)and concentration-weighted trajectory(CWT)models.Overall,the concentration of ambient VOCs in Haikou was strongly influenced by traffic sources and long-distance transport,and the control of VOCs emitted from vehicles should be strengthened to reduce the active species of ambient VOCs in Haikou,thereby reducing the generation of O_(3).
基金the Ministry of Land and Resource of P.R.China the National Natural Science Foundation of China(No.40172062).
文摘The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are recognized as two types. One was found in sandy gravel beds of the second terrace of the Yellow River. This ice-wedge pseudomorph is characterized by higher ratio of breadth/depth, and are 1-1.4 m wide and about 1 m deep. The bottom border of the ice-wedge pseudomorph is round arc in section. Another discovered in the pedestal of the second terrace has lower ratio of width/depth, and is o.3-1.0 m wide and 1-2 m deep. Its bottom border is sharp. Based on the TL dating, the former was formed at the middleHolocene （5.69±0.43 ka BP and 5.43±0.41 ka BP）, that is, the Megathermal, and the latter was formed at the late Last Glacial Maximum （13.49±1.43 ka BP）. Additionally, the thawing-freezing folders discovered in the late Late Pleistocene proluvium are 39.83±3.84 ka BP in age. The study on the ice-wedge pseudomorphs showed that the air temperature was lowered by up to 6-7℃ in the source area of the Yellow River when the ice-wedge pseudomorphs and thawing-freezing folds developed.
文摘Protection planning is made for rural centralized drinking water source areas according to current situations of rural drinking water and existing problems of centralized drinking water source areas in Chongqing,and in combination with survey,analysis and evaluation of urban-rural drinking water source areas in whole city.There are engineering measures and non-engineering measures,to guarantee drinking water security of rural residents,improve rural ecological environment,realize sustainable use of water resource,and promote sustainable development of society.Engineering measures include conservation and protection of water resource,ecological restoration,isolation,and comprehensive control of pointsource and area-source pollution.Non-engineering measures include construction of monitoring system for drinking water source area,construction of security information system for rural centralized drinking water source area,and construction of emergency mechanism for water pollution accidents in rural water source areas.
基金supported by Zhejiang A&F University(2022LFR083)Key R&D Program of Zhejiang Province(2021C02038)the International Centre for Bamboo and Rattan(1632021006)。
文摘Nitrogen(N)present in drinking water as dissolved nitrates can directly affect people’s health,making it important to control N pollution in water source areas.N pollution caused by agricultural fertilizers can be controlled by reducing the amount of fertilizer applied,but pollution caused by soil and water erosion in hilly areas can only be controlled by conservation forests.The catchment area around Fushi Reservoir was selected as a test site and mechanisms of N loss from a vertical spatial perspective through field observations were determined.The main N losses occurred from June to September,accounting for 85.9-95.9%of the annual loss,with the losses in June and July accounting for 46.0%of the total,and in August and September for 41.9%.The N leakage from the water source area was effectively reduced by 38.2%through the optimization of the stand structure of the conservation forests.Establishing well-structured forests for water conservation is crucial to ensure the security of drinking water.This preliminary research lays the foundation for revealing then loss mechanisms in water source areas and improving the control of non-point source pollution in these areas.
基金supported in part by the Programs of National Natural Science Foundation of China (41675157, 91537212)
文摘In this study,in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture prod ucts from NASA(National Aeronautics and Space Administration),JAXA(Japanese Aerospace Exploration Agency)and VUA(Vrije University Amsterdam and NASA)over Maqu County,Source Area of the Yellow River(SAYR),China.Re sults show that the VUA soil moisture product performs the best among the three AMSR-E soil moisture products in the study area,with a minimum RMSE(root mean square error)of 0.08(0.10)m3/m3 and smallest absolute error of 0.07(0.08)m3/m3 at the grassland area with ascending(descending)data.Therefore,the VUA soil moisture product is used to describe the spatial variation of soil moisture during the 2010 growing season over SAYR.The VUA soil moisture product shows that soil moisture presents a declining trend from east south(0.42 m3/m3)to west north(0.23 m3/m3),with good agreement with a general precipitation distribution.The center of SAYR presents extreme wetness(0.60 m3/m3)dur ing the whole study period,especially in July,while the head of SAYR presents a high level soil moisture(0.23 m3/m3)in July,August and September.
基金Supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2012ZX07103-005-01,2012ZX07103-004-02)the National Natural Science Foundation of China(Nos.41171366,41471075)the Science Foundation of Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2012135013)
文摘We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.
基金Foundation project:the Specific Research on Public Service of Environmental Protection in China(201009009)
文摘Based on the dynamic analysis and research of pollution risk of groundwater sources,this paper creates the dynamic assessment method of pollution risk of groundwater source area under the theory of"source-pathway-receptor",and applies this method to one typical fissure karst groundwater source area in northern China.Following the 30-year petroleum pollutant migration simulation and pollution risk assessment of groundwater source area,this study finds that the very high risk zone is mainly located in Q Petrochemical Company and the surrounding area and the area adjacent to River Z.Within this period of thirty years,the pollution risk of groundwater source area has showed a dynamic trend that features an inverted"V"shape.The ratio of very high risk zone to the total area will be 18.1%,17.47%and 16.62%during the tenth year,the twentieth year and the thirtieth year separately,and will reach the highest level of 19.45%during the fifteenth year.Meanwhile,the vertical migration distance of pollutant centre concentration changed from the surface soil at the outset to the deepest point of about 250 meters underground during the tenth year.The results of this risk assessment indicate the dynamic feature of pollution risk.The dilution,degradation and migration of petroleum pollutants in groundwater system contribute to an ultimate decline in pollution risk.
文摘The Shitoukoumen Reservoir is one of main drinking water source areas in Changchun City,and there is a contradiction between the protection and the economic development of water source areas. In this paper,the primary and secondary reserves in drinking water source area of the Shitoukoumen Reservoir are taken as research objects. Based on the theory of ecological compensation,the ecological compensation standard is accounted and determined from different perspectives,and the suggestion of the phased ecological compensation in water source areas is proposed.
文摘The characteristics of seismogenic structures are an important basis for delineating the potential seismic source areas and determining the annual occurrence rate of earthquakes. The potential seismic source area does not only have the intension that “this area has the possibility for destructive earthquakes to occur in the future" but also means that earthquakes of high magnitude interval have the characteristics of similar recurrence. When determining the seismic activity parameters of a statistical unit, some active tectonic blocks in the unit may have different background earthquakes. In order to better reflect the heterogeneity in space of seismic activities, it is necessary to divide the potential seismic source areas into three orders. By analyzing the recurrence characteristics of earthquakes of high magnitude interval in the potential source area and calculating the occurrence probability of earthquakes of high magnitude interval in the potential seismic source area in the time window for prediction, the average annual occurrence rate of earthquakes can be obtained by the method of probability equivalent conversion in the time window for prediction. This would be helpful for considering the recurrence characteristics of strong earthquakes in potential source areas within the framework of seismic risk analysis of China. Besides, the insufficient frequency of characteristic earthquakes of the next high magnitude interval in the potential source area and the heterogeneity of strong earthquakes on seismogenic structures are analyzed to see their application in seismic risk analysis.
基金supported by the National Natural Science Foundation of China(Nos.42121004,42275107,and 42077205)the National Key Research and Development Plan(No.2023YFC3706202)+1 种基金the Foundational and Applied Basic Research in Guangzhou in 2023(No.2023A04J0251)the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province(No.2019B121205004)。
文摘This study tracked the characteristics of atmospheric wet deposition of the toxic element arsenic(As)at both urban(Guangzhou(GZ))and forested(Dinghushan Natural Reserve(DHS))sites within the Pearl River Delta(PRD)region between 2016 and 2019,examining its correlation with rainfall patterns.Additionally,by employing backward trajectory analysis and the potential source contribution function(PSCF)in conjunction with pertinent emission inventories,we pinpointed the main pathways of atmospheric arsenic transport and evaluated the emission contributions from priority source areas.The study revealed that the atmospheric arsenic wet deposition fluxes at the GZ and DHS sites exhibited a trend of increase followed by a decrease over the four-year period.Wet season deposition fluxes were more than triple those of the dry season,with urban site showing a difference of over four times.Notably,wet season As deposition at both sites was predominantly affected by heavy rainfall from marine air masses,constituting 31%of the total deposition.The predominant trajectory directions contributing to arsenic deposition at GZ and DHS were northeast(55%)and south(53%),respectively.The primary source areas for both sites were largely outside the PRD region,with the GZ site having 80%to 95%of its source area in the non-PRD region,compared to 69%to 88%at the DHS site.Furthermore,non-PRD areas contributed approximately 65%to arsenic emissions for both sites,with the industrial sector being the dominant emission source,exceeding 97%of the total emissions.
基金supported by the Natural Science Foundation of Qinghai Province,China(No.2021-ZJ940Q)the Open Project of State Key Laboratory of Plateau Ecology and Agriculture,Qinghai University(No.2022-ZZ-02)。
文摘As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and biogeochemistry.In the Sources Area of the Yellow River(SAYR),permafrost degradation has accelerated since the 1980s,and numerous thermokarst lakes have been discovered.In this paper,we use Sentinel-2 images to extract thermokarst lake boundaries and perform a regional-scale study on their geometry across the permafrost region in the SAYR.We also explored the spatiotemporal variations and potential drivers from the perspectives of the permafrost,climate,terrain and vegetation conditions.The results showed that there were 47,518 thermokarst lakes in 2021 with a total area of 190.22×106 m^(2),with an average size of 4,003.3 m^(2).The 44,928 ponds(≤10,000 m^(2))predominated the whole lake number(94.1%)but contributed to a small portion of the total lake area(28.8%).With 2,590 features(5.9%),small-sized(10,000 to 100,000 m^(2))and large-sized lakes(>100,000 m^(2))constituted up to 71.2%of the total lake area.Thermokarst lakes developed more significantly in warm permafrost regions than in cold permafrost areas;74.1%of lakes with a total area of 119.6×106 m^(2)(62.9%),were distributed in warm permafrost regions.Most thermokarst lakes were likely to develop within the elevation range of 4,500~4,800 m,on flat terrain(slope<10°),on SE and S aspects and in alpine meadow areas.The thermokarst lakes in the study region experienced significant shrinkage between 1990 and 2021,characterized by obvious lake drainage;the lake numbers decreased by 5418(56.1%),with a decreasing area of 58.63×106 m^(2)(49.0%).This shrinkage of the thermokarst lake area was attributable mainly to the intensified degradation of rich-ice permafrost thawing arising from continued climate warming,despite the wetting climatic trend.
基金the Knowledge Innovation Program,Chinese Academy of Sciences (KZCX2-YW-442)National Basic Research Program of China (2007CB407207)National Natural Science Foundation (40971236)
文摘Critical source areas （CSAs）, characterized by severe soil erosion and high sediment yield, are considered to have a high priority for conservation. How to identify CSAs and assess the effectiveness of conservation practices is a key issue in site-specific watershed management. The Soil and Water Assessment Tool （SWAT） model is a useful tool for site-specific conservation practices design and several studies have attempted to identify CSAs based on watershed models. However, limited research has reported about the effectiveness of conservation practices targeting CSAs. The aim of this study was to assess the effectiveness of conservation pracrices targeted on CSAs using the SWAT model. CSA was firstly identified based on the 4-year average yearly erosion of each HRU. Appropriate soil conservation practices were then designed for the CSAs. A scenario with conservation practices for the whole watershed was also established as the contrasting counter parts scheme and then compared to the outcome of CSA-targeted conservation practices. The result shows that SWAT can accurately simulate sediment yield in the study area. CSAs were mainly located in slope farmland areas and steep gullies, coinciding with the distribution of land use and slope. The identified CSA covered 20% of the HRUs and contributed on average 44% of sediment yield. Conservation practices targeting CSAs had higher sediment reduction effectiveness （24 115 t km-2 y-1） than conservation practice covering the whole watershed （20 290 t km-2 y-1）. Thus conservation practices targeting CSAs are more effective than broad conservation practices. We conclude that soil conservation practices focusing on CSAs do increase sediment reduction effectiveness. Targeting the placement of soil conservation practices based on the CSAs concept will assist water quality control in watersheds.
基金supported by National Natural Science Foundation of China(Grant Nos.40772022,40972006)State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Paleontology)Chinese Academy of Sciences(Grant No.10311)
文摘Jurassic rocks are abundantly developed in the source area of the Yangtze River,South Qinghai,with the greatest thickness of 6311 m,including five stratigraphic units:Qoimaco Formation,Buqu Formation,Xiali Formation,Suowa Formation,and Xueshan Formation.Based on sufficient fossils of bivalves,ammonites,and brachiopods,the major part of these formations is ascribed to the Middle Jurassic Bathonian to Callovian.No diagnostic fossils have been found from the Lower Qoimaco Formation or Upper Xueshan Formation,which could possibly contain in part Bajocian and Oxfordian taxa respectively.
