Microplastics have emerged as one of the most significant threats to the Earth's ecosystems due to their persistence,ability to carry high loads of contaminants,and biotoxicity.The Tibetan Plateau is a hotspot for...Microplastics have emerged as one of the most significant threats to the Earth's ecosystems due to their persistence,ability to carry high loads of contaminants,and biotoxicity.The Tibetan Plateau is a hotspot for global biodiversity conservation,but its ecosystem is fragile.This study systematically investigated the characteristics,distribution,sources,and ecological risk of microplastics in rivers and lakes across the Tibetan Plateau using the Laser Direct Infrared Imaging Spectroscopy(LDIR).The results indicated that the mean abundances of microplastics in water and sediments were 4250 items/m^(3)(n=50)and 3750 items/kg(n=44),respectively.Microplastics with small sizes(50-200μm),characterized by transparent and white fragments,were predominant.The most common polymers identified were polyamide(PA),polyurethane(PU),polyethylene terephthalate(PET),polyvinyl chloride(PVC),polypropylene(PP),and polyethylene(PE).Water sampling sites near urban/suburban effluent outfalls showed high levels of contamination.Microplastics in water are primarily derived from sewage effluent and atmospheric deposition.No single driver has been identified as the key factor influencing the spatial distribution of microplastics in water.The abundance of microplastics in sediments was significantly negatively correlated with the distance to the nearest city/town(p<0.01,R=-0.56)and significantly positively correlated with precipitation(p<0.01,R=0.60).Discarded or landfilled plastic waste is a major source of microplastics in sediments,which accumulate through transport by stormwater runoff caused by precipitation.Three ecological risk assessment models for microplastics were applied,and the high proportion of hazardous polymers such as PU,PVC,and PA was found to be responsible for the high ecological risk in the study area.This study provides an accurate and detailed exploration of the characteristics,sources,and spatial distribution of microplastic pollution by advanced automatic detection method in rivers and lakes on the Tibetan Plateau.展开更多
The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and envi...The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and environmental management strategies.This study comprehensively evaluates the evolution of the eco-environment in the“Two Mountains,Seven Rivers,and One Basin”(TSO)area of Shanxi Province from 2000 to 2020 based on fraction vegetation cover(FVC)derived from the Normalized Difference Vegetation Index(NDVI),net primary productivity(NPP)calculated via the Carnegie–Ames–Stanford approach(CASA),and the remote sensing ecological index(RSEI).The results indicate a significant improvement in the TSO’s eco-environment from 2000 to 2020,with the RSEI values increased from 0.34 in 2000 to 0.41 in 2020(an increase of 17.76%).Both FVC and NPP demonstrated notable upward trends,with FVC increasing by 22.74%and NPP by 53.11%.Spatially,FVC rose by 21.84%,19.72%and 26.06%,respectively in the Two Mountains,Seven Rivers,and the YRB in Shanxi Province.Similarly,the NPPs increased by 51.60%,48.60%,and 61.65%in these regions over the past 21 years.Both FVC and NPP exhibited decreasing patterns from southeast to northwest,with significant eco-environmental improvements in the northern region and slower recovery in the southern region.Precipitation was the primary causes influencing vegetation recovery,showing positive trends in the central and northern TSO regions,while this trend reversed in the southern.The RSEI value indicate substantial eco-environment improvements in the central and northern areas(Sanggan,Daqing and Hutuo River Basins),whereas the southern regions(e.g.,Zhang,Qin,Fen and Sushui River Basins)remain in poor grade.Human activities,particularly land use/cover changes marked by increased forestation and urbanization alongside decreased cultivated land,significantly affected vegetation cover patterns.This study provides scientific references for formulating policies on ecological construction and high-quality development in the YRB.展开更多
Urban rivers are one of the main water sources for local residents.However,the rapid industrialization and urbanization caused serious heavy metals pollution in urban rivers,which posed harmful impact on human health ...Urban rivers are one of the main water sources for local residents.However,the rapid industrialization and urbanization caused serious heavy metals pollution in urban rivers,which posed harmful impact on human health and ecosystem.In this study,134 sediment samples were collected fromurban rivers in a typical Economic and Technological Development Zone(ETDZ)to evaluate the contamination status,ecological risk,biotoxicity,and potential source of 8 heavy metals including arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),mercury(Hg),nickel(Ni),plumbum(Pb),and zinc(Zn).Results showed that the average concentrations of all 8 metals exceeded their corresponding background values and followed the trend:Cr(248.67 mg/kg)>Pb(123.58 mg/kg)>Zn(67.06 mg/kg)>Ni(47.19 mg/kg)>Cu(27.40 mg/kg)>As(16.15 mg/kg)>Cd(0.62mg/kg)>Hg(0.21mg/kg).A high contamination and accumulation tendency of Cd and Cr were found in the sediments.Moreover,Cd and Hg were the main contributors of ecological risk,and posed moderate to high risk.In terms of biotoxicity,all the sediment samples were harmful to benthic organisms.Two possible pollution sources of heavy metals were identified:one is a combined source of industrial and traffic pollution dominated by Cr and Pd,the other is an industrial pollution source consisting of six heavy metals(Ni,Zn,Cd,Hg,As,and Cu).This study provides insights into heavy metals pollution management and risk control in the ETDZ and similar urban rivers worldwide due to intense industrialization.展开更多
Pollution of transboundary rivers can result from anthropogenic activities in their watersheds.In this study,sediment traps were deployed to determine the fluxes,concentrations,and health risks associated with arsenic...Pollution of transboundary rivers can result from anthropogenic activities in their watersheds.In this study,sediment traps were deployed to determine the fluxes,concentrations,and health risks associated with arsenic,cadmium,mercury,lead,and iron in the estuaries of three transboundary rivers(Comoé,Bia,and Tanoé)in West Africa.Thus,the analysis of metal-associated sedimentation particle samples collected in rainy,flood,and dry seasons was required.Sediment traps were used to calculate the metal fluxes associated with sedimentation particles towards the Atlantic Ocean.Finally,the carcinogenic and non-carcinogenic risks of ingestion and dermal contact associated with sedimentation particles were assessed.The results showed that the total concentrations of trace metals in particulate matter were higher than in the UCC(Upper Crust Continental),with the exception of lead.The highest fluxes of lead,mercury,iron and arsenic associated with sedimented particles were observed during flood periods in the estuary of the Comoé,Bia and Tanoérivers.Cadmium fluxes associated with sedimentation particles were highest in the rainy season in the Bia and Comoéestuaries and in the flood season in the Tanoéestuary.Pearson’s correlation analysis and the enrichment factor showed that the trace metals were derived from anthropogenic activities such as mining and farming.In addition,contamination indices showed that sediment particles in the estuaries of the three rivers were severely contaminated with mercury.However,the results of potential human health risks associated with trace metals show that there is no probability of exposure of the community to harmful and carcinogenic effects through ingestion and dermal absorption of sediment particles.It is essential to integrate the information from this study into policy-and decision-making processes for better management of transboundary river water resources in coastal countries,particularly the Côte d’Ivoire.展开更多
The concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd,and Pb were determined in Doulonggang River,Xinyanggang River,Huangshagang River,Sheyanghe River,Guangaizongqu River,and Linhonghe River at the North of Jiangsu Pr...The concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd,and Pb were determined in Doulonggang River,Xinyanggang River,Huangshagang River,Sheyanghe River,Guangaizongqu River,and Linhonghe River at the North of Jiangsu Province in 2019.The annual average concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd and Pb in the six rivers were 2.20,1.22,4.53,21.9,0.13,2.79,1.77,4.00,2.97,3.87,0.01,0.19μg L^(-1)respectively.The highest concentration of most trace metals were found in Guangaizongqu River and Linhonghe River,and the lowest concentration were found in Xinyanggang River and Huangshagang River.The principal component analysis(PCA)resulted of two factors together explained 91.2%of the variance with>1initial eigenvalue,indicating that both natural and anthropogenic activities were contributing factors as the source of metal abundance in rivers of northern Jiangsu Province.The first major component represented the influence of anthropogenic activities,including industry and agriculture,with a contribution rate of 54.1%,affected Cr,Fe,Cu,Zn,Mo,Cd and Pb.The second(such as V,Mn,Co,Ni,As)was a mixed source,including the natural processes such as precipitation,erosion and weathering and anthropogenic action like industry and agriculture,with a contribution rate of 37.1%.Seasonal variations in trace metal concentrations were influenced by temperature,salinity,water discharge,and input of external pollutants.The highest concentrations were found in wet season and were strongly influenced by rainfall and seasonal industrial and agricultural activities.展开更多
Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and ...Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.展开更多
Based on regional paleoclimate sequences,records of human activities,paleoclimate simulations,and detailed environmental historical records,we discuss the impacts of Holocene climate change and human activities on the...Based on regional paleoclimate sequences,records of human activities,paleoclimate simulations,and detailed environmental historical records,we discuss the impacts of Holocene climate change and human activities on the evolution of the Shule River in the western Qilian Mountains,China.The results indicate that during the early to mid-Holocene,the river evolution of the Shule River alluvial fan was closely related to regional climate fluctuations.In the late Holocene,flood agriculture began to emerge along the Shule River.During the historical period,population growth and the expansion of arable land led to increased river water usage,resulting in decreased access to the expected distribution of water resources in other regions,which in turn has caused imbalances in the regional hydrological ecosystem.展开更多
Rivers are crucial in the spread of invasive plants.Invasive plants alter their seed traits to adapt to environmental changes and promote invasion.Studying the trait changes in invasive plant seeds may improve the und...Rivers are crucial in the spread of invasive plants.Invasive plants alter their seed traits to adapt to environmental changes and promote invasion.Studying the trait changes in invasive plant seeds may improve the understanding of their propagation mechanisms along the river and provide appropriate control measures.In this study,seven Ambrosia trifida populations along the Liaohe River were used as study subjects.The results showed that the seven A.trifida populations were closely related and exhibited a certain gene exchange,but the absence of evidence of directed gene flow among populations did not confirm that rivers were the medium of seed dispersal of A.trifida.Along the Liaohe River,from top to bottom,the positive view area,length,width,perimeter,and thousand seed weight of A.trifida seeds showed an increasing trend.The total nitrogen and phosphorus contents in the river water of the A.trifida population in the lower reaches of the Liaohe River were higher than those at the other sites.Furthermore,along the river,from top to bottom,the available nitrogen,total nitrogen,total potassium,available potassium,and organic matter contents in the soil in which A.trifida populations grew showed significant increasing trends.River structure,water quality,and soil nutrients had direct and indirect effects on seed morphology.Soil total nitrogen,available potassium,and organic matter had significant positive effects on seed positive view area and perimeter,suggesting that the maternal effect played a critical role in shaping seed morphology.Our analysis showed that soil nutrients along the river may be the primary driver that governs changes in A.trifida seed traits.展开更多
The widespread occurrence of antibiotics in urban rivers has raised global concerns for ecological security.Quantitative source-specific risk apportionment of antibiotics is crucial for targeted and effective ecologic...The widespread occurrence of antibiotics in urban rivers has raised global concerns for ecological security.Quantitative source-specific risk apportionment of antibiotics is crucial for targeted and effective ecological risk management,but is rarely studied.In this study,a source-specific ecological risk apportionment model for antibiotics was developed by combining the ecological risk quotient(RQ)method and the positive matrix factorization(PMF)model.Based on twenty-two antibiotics in sixty-five water samples from thirteen sites in Beijing in wet and dry seasons,the spatial variation and probabilistic distribution of ecological risk associated with antibiotics were analyzed,and source-specific ecological risk was evaluated.Results showed that for the sum of all antibiotics,the mean concentration of all samples was 671.48 ng/L,and the lower limit of the 90%confidence interval of RQs was more than ten times the threshold for the high-risk level.The main sources were identified as domestic sewage,pharmaceutical wastewater and livestock discharge.It should be noted that higher contributions to antibiotic concentrations from sources do not always result in higher levels of ecological risk.Domestic sewage and livestock discharge contributed roughly equivalent amounts(36.17%and 37.59%,respectively)to antibiotic concentrations.However,domestic sewage was the most dominant source for risk(63.30%),and livestock discharge only contributed 7.37%to risk.The study found that evaluating the source-specific ecological risk associated with antibiotics is essential in addition to identifying their sources.The source-specific ecological risk apportionment model developed in this study is also referential for related studies.展开更多
The Yellow River(YR),China’s second-longest river,remains understudied regarding its greenhouse gases(GHGs)emissions,particularly the impacts of urban drainage ditches and wastewater treatment facilities on regional ...The Yellow River(YR),China’s second-longest river,remains understudied regarding its greenhouse gases(GHGs)emissions,particularly the impacts of urban drainage ditches and wastewater treatment facilities on regional GHGs dynamics.This study investigated methane(CH_(4))and carbon dioxide(CO_(2))concentrations,fluxes and stable carbon isotopes(δ^(13)C-CH_(4)and δ^(13)C-CO_(2))across six main stream,three ditches,and one wastewater treatment site along the upper Lanzhou section of the YR,spanning from the urban entrance(36.176°N,103.449°E)to the exit of Lanzhou city(36.056°N,104.020°E).Measured CH_(4)diffusion fluxes in mainstem sites ranged from 0.01 to 2.58 mmol·m^(−2)·d^(−1)(mean:0.36 mmol·m^(−2)·d^(−1)),while ebullitive fluxes(gas bubbles)ranged from 0.01 to 18.89 mmol·m^(−2)·d^(−1)(mean:0.90 mmol·m^(−2)·d^(−1)).CO_(2)diffusion fluxes varied between 9.16–92.80 mmol·m^(−2)·d^(−1)(averaged:39.11 mmol·m^(−2)·d^(−1))at these locations.Ebullition(bubble)fluxes accounted for 53.1%±22.4%(range:9.0%to 98.4%)to total CH_(4)emissions(diffusion plus ebullition),with peak fluxes occurring during summer,indicating its significance as a CH_(4)transport mechanism.Notably,both diffusion CH_(4)and CO_(2)fluxes and ebullitive CH_(4)rates at ditch sites substantially exceeded those in mainstream reaches.The lowest CH_(4)and highest CO_(2)concentrations were observed at a wastewater treatment site,likely resulting from the removal of high organic loads.Acetoclastic methanogenesis—the process converting acetate-derived methyl groups to CH_(4)—was identified as the dominant production pathway in both mainstream and ditch environments.CH_(4)and CO_(2)flux magnitudes in the upper YR(Lanzhou section)were comparable to those observed in subtropical Yangtze River tributaries.These results demonstrate that anthropogenic influences significantly enhance CO_(2)/CH_(4)emissions,and the lateral exports of dissolved carbon(DIC and DOC)in the main stream site was quantified.,which cannot be overlooked.The findings emphasize the critical need to account for pronounced spatiotemporal variations in arid-region GHG fluxes to improve basin-scale estimates for the YR.展开更多
River ethics encompasses the values,moral principles,and behavioral norms that govern and regulate the relationship between humans and rivers.Constructing rivers ethics breaks through the traditional ethical dimension...River ethics encompasses the values,moral principles,and behavioral norms that govern and regulate the relationship between humans and rivers.Constructing rivers ethics breaks through the traditional ethical dimension that is limited to interpersonal judgment and extends the moral relationship from solely between humans to between humans and river life.China's eco-civilization drive elucidates that harmony between humans and rivers are the core concept of constructing river ethics.This paper discusses the values,foundation,moral principles,and behavioral norms of river ethics,and forms the theoretical framework of river ethics.展开更多
Rivers provide key ecosystem services that are inherently engineered and optimized to meet the strategic and economic needs of countries around the world.However,limited water quality records of a full river continuum...Rivers provide key ecosystem services that are inherently engineered and optimized to meet the strategic and economic needs of countries around the world.However,limited water quality records of a full river continuum hindered the understanding of how river systems response to the multiple stressors acting on them.This study highlights the use of Sentinel-2 Multi-Spectral Imager(MSI)data to monitor changes in water color in two optically complex river systems:the Yangtze and Danube using the Forel-Ule Index(FUI).FUI divides water color into 21 classes from dark blue to yellowish brown stemming from the historical Forel-Ule water color scale and has been promoted as a useful indicator showing water turbidity variations in water bodies.The results revealed contrasting water color patterns in the two rivers on both spatial and seasonal scales.Spatially,the FUI of the Yangtze River gradually increased from the upper reaches to the lower reaches,while the FUI of the Danube River declined in the lower reaches,which is possibly due to the sediment sink effect of the Iron Gate Dams.The regional FUI peaks and valleys observed in the two river systems have also been shown to be related to the dams and hydropower stations along them.Seasonally,the variations of FUI in both systems can be attributed to climate seasonality,especially precipitation in the basin and the water level.Moreover,land cover within the river basin was possibly a significant determinant of water color,as higher levels of vegetation in the Danube basin were associated with lower FUI values,whereas higher FUI values and lower levels of vegetation were observed in the Yangtze system.This study furthers our knowledge of using Sentinel-2 MSI to monitor and understand the spatial-temporal variations of river systems and highlights the capabilities of the FUI in an optically complex environment.展开更多
Since time immemorial,humans have made their homes alongside waterways,and mighty rivers have been the cradles of human civilization.However,as society has evolved at an ever-accelerating pace,our relationship with th...Since time immemorial,humans have made their homes alongside waterways,and mighty rivers have been the cradles of human civilization.However,as society has evolved at an ever-accelerating pace,our relationship with these life-giving streams has shifted dramatically,from one of reverence to exploitation.Now,the profound water crisis has compelled humanity to reexamine its connection with rivers.展开更多
In this paper,the definition,connotation,and internal relationship of mountains,rivers,forests,farmlands,lakes,and grasslands in China are elaborated,and the current situation of ecological restoration projects for mo...In this paper,the definition,connotation,and internal relationship of mountains,rivers,forests,farmlands,lakes,and grasslands in China are elaborated,and the current situation of ecological restoration projects for mountains,rivers,forests,farmlands,lakes,and grasslands was introduced.Moreover,the problems that have arisen in the specific implementation process of pilot projects were analyzed,such as unclear target positioning,inaccurate analysis of ecological problems,insufficient engineering design systematicness,weak operability of evaluation standards,and weak coordination in engineering management.The development direction and major needs for the protection and restoration of mountains,rivers,forests,farmlands,lakes,and grasslands in the future have been proposed from four aspects:theoretical research,engineering design,effect evaluation,and monitoring and supervision.展开更多
The main urban area of Chongqing is surrounded by two rivers and set against each other.With its unique waterfront landscape,it has the resource conditions to become a leisure tourism destination.Intending to enhance ...The main urban area of Chongqing is surrounded by two rivers and set against each other.With its unique waterfront landscape,it has the resource conditions to become a leisure tourism destination.Intending to enhance people’s happiness,improve city quality,and promote Chongqing’s main urban area to become a tourist destination,this paper finds out the existing problems in the construction of public outdoor leisure and fitness facilities on the two rivers and four banks of Chongqing’s main urban area through investigation and analysis based on relevant experiences at home and abroad,takes the value chain theory as the guidance,and to find solutions to the problem.On this basis,combined with the law of economic operation,this paper puts forward the guiding ideology,principles,development goals,functional orientation,and development path for the improvement of public outdoor leisure and fitness on two rivers and four banks in the main city of Chongqing,and accordingly puts forward the policy system and guarantee measures for its improvement.展开更多
The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphi...The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.展开更多
This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged...This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312items kg^(-1)dry sediment across different survey stations,with an average abundance at(4388±713)items kg^(-1)dry sediment.Upon further categorization,it was found that transparent fragments were the primary color and type of microplastics present.The potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers studied.Cd was identified as the main potential ecological risk factor in the sediments of the studied areas.There was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage between these two environmental pollutants.However,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in sediments.In fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the sediments.This finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.展开更多
The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acce...The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acceptable,we investigated the geomorphology of the Himalayas between eastern Nepal and Bhutan Himalayas.The southern part of Tibetan Plateau,extending across the Himalayas as tectonically un-deformed glaciated terrain named as'Tibetan Corridor,'does not suggest the regional uplift of the Higher Himalayas.The 8,000-m class mountains of Everest,Makalu,and Kanchenjunga are isolated residual peaks on the glaciated terrain composed of mountain peaks of 4,000–6,000 m high.The Tibetan glaciers commonly beheaded by Himalayan glaciers along the great watershed of the Himalayas suggest the expansion of Himalayan river drainage by glaciation.For the narrow upstream regions of the Arun and Tista Rivers with less precipitation behind the range,it is hard to collect enough water for the power of down-cutting their channels against the uplifting Himalayas.The fission track ages of the Higher Himalayan Crystalline Nappe suggest that the Himalayas attained their present altitude by 11–10 Ma,and the Arun and Tista Rivers formed deep gorges across the Himalayas by headward erosion.展开更多
Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological env...Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological environment of estuaries and bays.In order to investigate the seasonal characteristics of nutrients in small mountainous rivers in the subtropical monsoon region and the output pattern to the sea during heavy precipitation,surveys on the mountainous rivers were carried out in Baixi watershed in August 2020(wet season),March 2021(dry season)and June 2021(Meiyu period).The results showed that the dissolved inorganic nitrogen(DIN)of the rivers has an average concentration of 752μg L^(−1)in the wet season and 1472μg L^(−1)in the dry season.The concentrations of dissolved inorganic phosphorus(DIP)in wet season and dry season were 63μg L^(−1)and 51μg L^(−1),respectively.Influenced by the changes of land use in sub-watersheds,DIN concentrations in the mainstream increased from 701μg L^(−1)in the upper reaches to 1284μg L^(−1)in the middle reaches.Two rainstorms during the Meiyu period in the watershed caused the pulse runoff in the river.The maximum daily runoff reached 70 times that before rains.The maximum daily fluxes of DIN and DIP were 109 and 247 times that before rains,respectively.In view that the watershed experienced several rainstorms in the wet season,the river,with pulse runoff,carries a large amount of nutrients into the sea in a short time,which will have a significant impact on the environment of Sanmen bay and its adjacent sea.展开更多
To understand the CH_(4) flux variations and their climatic drivers in the rice-wheat agroecosystem in the Huai River Basin of China,the CH_(4) flux was observed by using open-path eddy covariance at a typical rice-wh...To understand the CH_(4) flux variations and their climatic drivers in the rice-wheat agroecosystem in the Huai River Basin of China,the CH_(4) flux was observed by using open-path eddy covariance at a typical rice-wheat rotation system in Anhui Province,China from November 2019 to October 2021.The variations and their drivers were then analyzed with the Akaike information criterion method.CH_(4) flux showed distinct diurnal variations with single peaks during 9:00-13:00 local time.The highest peak was 2.15μg m^(-2)s^(-1)which occurred at 11:00 in the vegetative growth stage in the rice growing season(RGS).CH_(4) flux also showed significant seasonal variations.The average CH_(4)flux in the vegetative growth stage in the RGS(193.8±74.2 mg m^(-2)d^(-1))was the highest among all growth stages.The annual total CH_(4) flux in the non-rice growing season(3.2 g m^(-2))was relatively small compared to that in the RGS(23.9 g m^(-2)).CH_(4) flux increased significantly with increase in air temperature,soil temperature,and soil water content in both the RGS and the non-RGS,while it decreased significantly with increase in vapor pressure deficit in the RGS.This study provided a comprehensive understanding of the CH_(4) flux and its drivers in the rice-wheat rotation agroecosystem in the Huai River Basin of China.In addition,our findings will be helpful for the validation and adjustment of the CH_(4) models in this region.展开更多
基金supported by the National Natural Science Foundation of China(42322105)Outstanding Youth Fund of Gansu Province(23JRRA612)Postdoctoral Fellowship Program of CPSF(GZC20232952).
文摘Microplastics have emerged as one of the most significant threats to the Earth's ecosystems due to their persistence,ability to carry high loads of contaminants,and biotoxicity.The Tibetan Plateau is a hotspot for global biodiversity conservation,but its ecosystem is fragile.This study systematically investigated the characteristics,distribution,sources,and ecological risk of microplastics in rivers and lakes across the Tibetan Plateau using the Laser Direct Infrared Imaging Spectroscopy(LDIR).The results indicated that the mean abundances of microplastics in water and sediments were 4250 items/m^(3)(n=50)and 3750 items/kg(n=44),respectively.Microplastics with small sizes(50-200μm),characterized by transparent and white fragments,were predominant.The most common polymers identified were polyamide(PA),polyurethane(PU),polyethylene terephthalate(PET),polyvinyl chloride(PVC),polypropylene(PP),and polyethylene(PE).Water sampling sites near urban/suburban effluent outfalls showed high levels of contamination.Microplastics in water are primarily derived from sewage effluent and atmospheric deposition.No single driver has been identified as the key factor influencing the spatial distribution of microplastics in water.The abundance of microplastics in sediments was significantly negatively correlated with the distance to the nearest city/town(p<0.01,R=-0.56)and significantly positively correlated with precipitation(p<0.01,R=0.60).Discarded or landfilled plastic waste is a major source of microplastics in sediments,which accumulate through transport by stormwater runoff caused by precipitation.Three ecological risk assessment models for microplastics were applied,and the high proportion of hazardous polymers such as PU,PVC,and PA was found to be responsible for the high ecological risk in the study area.This study provides an accurate and detailed exploration of the characteristics,sources,and spatial distribution of microplastic pollution by advanced automatic detection method in rivers and lakes on the Tibetan Plateau.
基金This research was supported by the Fundamental Research Program of Shanxi Province(202203021212497,20210302123265)the Shanxi Normal University School Fund(Research Project on Major Issues of High-Quality Development in Shanxi Province,GZLFZ2327).
文摘The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and environmental management strategies.This study comprehensively evaluates the evolution of the eco-environment in the“Two Mountains,Seven Rivers,and One Basin”(TSO)area of Shanxi Province from 2000 to 2020 based on fraction vegetation cover(FVC)derived from the Normalized Difference Vegetation Index(NDVI),net primary productivity(NPP)calculated via the Carnegie–Ames–Stanford approach(CASA),and the remote sensing ecological index(RSEI).The results indicate a significant improvement in the TSO’s eco-environment from 2000 to 2020,with the RSEI values increased from 0.34 in 2000 to 0.41 in 2020(an increase of 17.76%).Both FVC and NPP demonstrated notable upward trends,with FVC increasing by 22.74%and NPP by 53.11%.Spatially,FVC rose by 21.84%,19.72%and 26.06%,respectively in the Two Mountains,Seven Rivers,and the YRB in Shanxi Province.Similarly,the NPPs increased by 51.60%,48.60%,and 61.65%in these regions over the past 21 years.Both FVC and NPP exhibited decreasing patterns from southeast to northwest,with significant eco-environmental improvements in the northern region and slower recovery in the southern region.Precipitation was the primary causes influencing vegetation recovery,showing positive trends in the central and northern TSO regions,while this trend reversed in the southern.The RSEI value indicate substantial eco-environment improvements in the central and northern areas(Sanggan,Daqing and Hutuo River Basins),whereas the southern regions(e.g.,Zhang,Qin,Fen and Sushui River Basins)remain in poor grade.Human activities,particularly land use/cover changes marked by increased forestation and urbanization alongside decreased cultivated land,significantly affected vegetation cover patterns.This study provides scientific references for formulating policies on ecological construction and high-quality development in the YRB.
基金supported by the National Key Research and Development Plan of China(No.2022YFE0197200)the National Natural Science Foundation of China(No.42277055).
文摘Urban rivers are one of the main water sources for local residents.However,the rapid industrialization and urbanization caused serious heavy metals pollution in urban rivers,which posed harmful impact on human health and ecosystem.In this study,134 sediment samples were collected fromurban rivers in a typical Economic and Technological Development Zone(ETDZ)to evaluate the contamination status,ecological risk,biotoxicity,and potential source of 8 heavy metals including arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),mercury(Hg),nickel(Ni),plumbum(Pb),and zinc(Zn).Results showed that the average concentrations of all 8 metals exceeded their corresponding background values and followed the trend:Cr(248.67 mg/kg)>Pb(123.58 mg/kg)>Zn(67.06 mg/kg)>Ni(47.19 mg/kg)>Cu(27.40 mg/kg)>As(16.15 mg/kg)>Cd(0.62mg/kg)>Hg(0.21mg/kg).A high contamination and accumulation tendency of Cd and Cr were found in the sediments.Moreover,Cd and Hg were the main contributors of ecological risk,and posed moderate to high risk.In terms of biotoxicity,all the sediment samples were harmful to benthic organisms.Two possible pollution sources of heavy metals were identified:one is a combined source of industrial and traffic pollution dominated by Cr and Pd,the other is an industrial pollution source consisting of six heavy metals(Ni,Zn,Cd,Hg,As,and Cu).This study provides insights into heavy metals pollution management and risk control in the ETDZ and similar urban rivers worldwide due to intense industrialization.
文摘Pollution of transboundary rivers can result from anthropogenic activities in their watersheds.In this study,sediment traps were deployed to determine the fluxes,concentrations,and health risks associated with arsenic,cadmium,mercury,lead,and iron in the estuaries of three transboundary rivers(Comoé,Bia,and Tanoé)in West Africa.Thus,the analysis of metal-associated sedimentation particle samples collected in rainy,flood,and dry seasons was required.Sediment traps were used to calculate the metal fluxes associated with sedimentation particles towards the Atlantic Ocean.Finally,the carcinogenic and non-carcinogenic risks of ingestion and dermal contact associated with sedimentation particles were assessed.The results showed that the total concentrations of trace metals in particulate matter were higher than in the UCC(Upper Crust Continental),with the exception of lead.The highest fluxes of lead,mercury,iron and arsenic associated with sedimented particles were observed during flood periods in the estuary of the Comoé,Bia and Tanoérivers.Cadmium fluxes associated with sedimentation particles were highest in the rainy season in the Bia and Comoéestuaries and in the flood season in the Tanoéestuary.Pearson’s correlation analysis and the enrichment factor showed that the trace metals were derived from anthropogenic activities such as mining and farming.In addition,contamination indices showed that sediment particles in the estuaries of the three rivers were severely contaminated with mercury.However,the results of potential human health risks associated with trace metals show that there is no probability of exposure of the community to harmful and carcinogenic effects through ingestion and dermal absorption of sediment particles.It is essential to integrate the information from this study into policy-and decision-making processes for better management of transboundary river water resources in coastal countries,particularly the Côte d’Ivoire.
基金funded by the National Natural Science Foundation of China(Nos.42130410)the Joint Fund between NSFC and Shandong Province(No.U1906210)。
文摘The concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd,and Pb were determined in Doulonggang River,Xinyanggang River,Huangshagang River,Sheyanghe River,Guangaizongqu River,and Linhonghe River at the North of Jiangsu Province in 2019.The annual average concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd and Pb in the six rivers were 2.20,1.22,4.53,21.9,0.13,2.79,1.77,4.00,2.97,3.87,0.01,0.19μg L^(-1)respectively.The highest concentration of most trace metals were found in Guangaizongqu River and Linhonghe River,and the lowest concentration were found in Xinyanggang River and Huangshagang River.The principal component analysis(PCA)resulted of two factors together explained 91.2%of the variance with>1initial eigenvalue,indicating that both natural and anthropogenic activities were contributing factors as the source of metal abundance in rivers of northern Jiangsu Province.The first major component represented the influence of anthropogenic activities,including industry and agriculture,with a contribution rate of 54.1%,affected Cr,Fe,Cu,Zn,Mo,Cd and Pb.The second(such as V,Mn,Co,Ni,As)was a mixed source,including the natural processes such as precipitation,erosion and weathering and anthropogenic action like industry and agriculture,with a contribution rate of 37.1%.Seasonal variations in trace metal concentrations were influenced by temperature,salinity,water discharge,and input of external pollutants.The highest concentrations were found in wet season and were strongly influenced by rainfall and seasonal industrial and agricultural activities.
基金funded by the Postdoctoral Research Startup Foundation of University of Jinan(Grant No.100389917).
文摘Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.
基金The National Natural Science Foundation of China(Grant 42371159)。
文摘Based on regional paleoclimate sequences,records of human activities,paleoclimate simulations,and detailed environmental historical records,we discuss the impacts of Holocene climate change and human activities on the evolution of the Shule River in the western Qilian Mountains,China.The results indicate that during the early to mid-Holocene,the river evolution of the Shule River alluvial fan was closely related to regional climate fluctuations.In the late Holocene,flood agriculture began to emerge along the Shule River.During the historical period,population growth and the expansion of arable land led to increased river water usage,resulting in decreased access to the expected distribution of water resources in other regions,which in turn has caused imbalances in the regional hydrological ecosystem.
基金funded by the National Key Research and Development Program of China(2022YFF1301004)the National Key R&D Program(2023YFC2604500).
文摘Rivers are crucial in the spread of invasive plants.Invasive plants alter their seed traits to adapt to environmental changes and promote invasion.Studying the trait changes in invasive plant seeds may improve the understanding of their propagation mechanisms along the river and provide appropriate control measures.In this study,seven Ambrosia trifida populations along the Liaohe River were used as study subjects.The results showed that the seven A.trifida populations were closely related and exhibited a certain gene exchange,but the absence of evidence of directed gene flow among populations did not confirm that rivers were the medium of seed dispersal of A.trifida.Along the Liaohe River,from top to bottom,the positive view area,length,width,perimeter,and thousand seed weight of A.trifida seeds showed an increasing trend.The total nitrogen and phosphorus contents in the river water of the A.trifida population in the lower reaches of the Liaohe River were higher than those at the other sites.Furthermore,along the river,from top to bottom,the available nitrogen,total nitrogen,total potassium,available potassium,and organic matter contents in the soil in which A.trifida populations grew showed significant increasing trends.River structure,water quality,and soil nutrients had direct and indirect effects on seed morphology.Soil total nitrogen,available potassium,and organic matter had significant positive effects on seed positive view area and perimeter,suggesting that the maternal effect played a critical role in shaping seed morphology.Our analysis showed that soil nutrients along the river may be the primary driver that governs changes in A.trifida seed traits.
基金funded by the National Natural Science Foundation of China(Nos.52400245 and 5221101156)the National Key Research and Development Program of China(No.2017ZX07103)。
文摘The widespread occurrence of antibiotics in urban rivers has raised global concerns for ecological security.Quantitative source-specific risk apportionment of antibiotics is crucial for targeted and effective ecological risk management,but is rarely studied.In this study,a source-specific ecological risk apportionment model for antibiotics was developed by combining the ecological risk quotient(RQ)method and the positive matrix factorization(PMF)model.Based on twenty-two antibiotics in sixty-five water samples from thirteen sites in Beijing in wet and dry seasons,the spatial variation and probabilistic distribution of ecological risk associated with antibiotics were analyzed,and source-specific ecological risk was evaluated.Results showed that for the sum of all antibiotics,the mean concentration of all samples was 671.48 ng/L,and the lower limit of the 90%confidence interval of RQs was more than ten times the threshold for the high-risk level.The main sources were identified as domestic sewage,pharmaceutical wastewater and livestock discharge.It should be noted that higher contributions to antibiotic concentrations from sources do not always result in higher levels of ecological risk.Domestic sewage and livestock discharge contributed roughly equivalent amounts(36.17%and 37.59%,respectively)to antibiotic concentrations.However,domestic sewage was the most dominant source for risk(63.30%),and livestock discharge only contributed 7.37%to risk.The study found that evaluating the source-specific ecological risk associated with antibiotics is essential in addition to identifying their sources.The source-specific ecological risk apportionment model developed in this study is also referential for related studies.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0950000)the NSFC(Grant No.42201155+2 种基金4240114742201137)the State Key Laboratory of Cryospheric Science and Frozen Soil Engineering(CSFSE-ZQ-2410).
文摘The Yellow River(YR),China’s second-longest river,remains understudied regarding its greenhouse gases(GHGs)emissions,particularly the impacts of urban drainage ditches and wastewater treatment facilities on regional GHGs dynamics.This study investigated methane(CH_(4))and carbon dioxide(CO_(2))concentrations,fluxes and stable carbon isotopes(δ^(13)C-CH_(4)and δ^(13)C-CO_(2))across six main stream,three ditches,and one wastewater treatment site along the upper Lanzhou section of the YR,spanning from the urban entrance(36.176°N,103.449°E)to the exit of Lanzhou city(36.056°N,104.020°E).Measured CH_(4)diffusion fluxes in mainstem sites ranged from 0.01 to 2.58 mmol·m^(−2)·d^(−1)(mean:0.36 mmol·m^(−2)·d^(−1)),while ebullitive fluxes(gas bubbles)ranged from 0.01 to 18.89 mmol·m^(−2)·d^(−1)(mean:0.90 mmol·m^(−2)·d^(−1)).CO_(2)diffusion fluxes varied between 9.16–92.80 mmol·m^(−2)·d^(−1)(averaged:39.11 mmol·m^(−2)·d^(−1))at these locations.Ebullition(bubble)fluxes accounted for 53.1%±22.4%(range:9.0%to 98.4%)to total CH_(4)emissions(diffusion plus ebullition),with peak fluxes occurring during summer,indicating its significance as a CH_(4)transport mechanism.Notably,both diffusion CH_(4)and CO_(2)fluxes and ebullitive CH_(4)rates at ditch sites substantially exceeded those in mainstream reaches.The lowest CH_(4)and highest CO_(2)concentrations were observed at a wastewater treatment site,likely resulting from the removal of high organic loads.Acetoclastic methanogenesis—the process converting acetate-derived methyl groups to CH_(4)—was identified as the dominant production pathway in both mainstream and ditch environments.CH_(4)and CO_(2)flux magnitudes in the upper YR(Lanzhou section)were comparable to those observed in subtropical Yangtze River tributaries.These results demonstrate that anthropogenic influences significantly enhance CO_(2)/CH_(4)emissions,and the lateral exports of dissolved carbon(DIC and DOC)in the main stream site was quantified.,which cannot be overlooked.The findings emphasize the critical need to account for pronounced spatiotemporal variations in arid-region GHG fluxes to improve basin-scale estimates for the YR.
文摘River ethics encompasses the values,moral principles,and behavioral norms that govern and regulate the relationship between humans and rivers.Constructing rivers ethics breaks through the traditional ethical dimension that is limited to interpersonal judgment and extends the moral relationship from solely between humans to between humans and river life.China's eco-civilization drive elucidates that harmony between humans and rivers are the core concept of constructing river ethics.This paper discusses the values,foundation,moral principles,and behavioral norms of river ethics,and forms the theoretical framework of river ethics.
基金sponsored by the Dragon 5 Cooperation(grant number 59193)the International Partnership Program of Chinese Academy of Sciences(grant number 313GJHZ2022085FN)+1 种基金the European Union’s Horizon Europe research and innovation programme project DANUBE4all(grant number 101093985)Fund of the International Research Center of Big Data for Sustainable Development Goals(Grant No.CBAS2022DF004).
文摘Rivers provide key ecosystem services that are inherently engineered and optimized to meet the strategic and economic needs of countries around the world.However,limited water quality records of a full river continuum hindered the understanding of how river systems response to the multiple stressors acting on them.This study highlights the use of Sentinel-2 Multi-Spectral Imager(MSI)data to monitor changes in water color in two optically complex river systems:the Yangtze and Danube using the Forel-Ule Index(FUI).FUI divides water color into 21 classes from dark blue to yellowish brown stemming from the historical Forel-Ule water color scale and has been promoted as a useful indicator showing water turbidity variations in water bodies.The results revealed contrasting water color patterns in the two rivers on both spatial and seasonal scales.Spatially,the FUI of the Yangtze River gradually increased from the upper reaches to the lower reaches,while the FUI of the Danube River declined in the lower reaches,which is possibly due to the sediment sink effect of the Iron Gate Dams.The regional FUI peaks and valleys observed in the two river systems have also been shown to be related to the dams and hydropower stations along them.Seasonally,the variations of FUI in both systems can be attributed to climate seasonality,especially precipitation in the basin and the water level.Moreover,land cover within the river basin was possibly a significant determinant of water color,as higher levels of vegetation in the Danube basin were associated with lower FUI values,whereas higher FUI values and lower levels of vegetation were observed in the Yangtze system.This study furthers our knowledge of using Sentinel-2 MSI to monitor and understand the spatial-temporal variations of river systems and highlights the capabilities of the FUI in an optically complex environment.
文摘Since time immemorial,humans have made their homes alongside waterways,and mighty rivers have been the cradles of human civilization.However,as society has evolved at an ever-accelerating pace,our relationship with these life-giving streams has shifted dramatically,from one of reverence to exploitation.Now,the profound water crisis has compelled humanity to reexamine its connection with rivers.
基金Basic Research Business Funding Project for Public Welfare Research Institutes in the Autonomous Region in 2022(kyys202201).
文摘In this paper,the definition,connotation,and internal relationship of mountains,rivers,forests,farmlands,lakes,and grasslands in China are elaborated,and the current situation of ecological restoration projects for mountains,rivers,forests,farmlands,lakes,and grasslands was introduced.Moreover,the problems that have arisen in the specific implementation process of pilot projects were analyzed,such as unclear target positioning,inaccurate analysis of ecological problems,insufficient engineering design systematicness,weak operability of evaluation standards,and weak coordination in engineering management.The development direction and major needs for the protection and restoration of mountains,rivers,forests,farmlands,lakes,and grasslands in the future have been proposed from four aspects:theoretical research,engineering design,effect evaluation,and monitoring and supervision.
基金funded by the Humanities and Social Sciences Research Planning Fund of the Ministry of Education of the People’s Republic of China,entitled“Research on the Application and Improvement of PPP Model for the Construction of Sports and Leisure Characteristic Towns Based on Value Chain Theory”(Project No.18XJA890002).
文摘The main urban area of Chongqing is surrounded by two rivers and set against each other.With its unique waterfront landscape,it has the resource conditions to become a leisure tourism destination.Intending to enhance people’s happiness,improve city quality,and promote Chongqing’s main urban area to become a tourist destination,this paper finds out the existing problems in the construction of public outdoor leisure and fitness facilities on the two rivers and four banks of Chongqing’s main urban area through investigation and analysis based on relevant experiences at home and abroad,takes the value chain theory as the guidance,and to find solutions to the problem.On this basis,combined with the law of economic operation,this paper puts forward the guiding ideology,principles,development goals,functional orientation,and development path for the improvement of public outdoor leisure and fitness on two rivers and four banks in the main city of Chongqing,and accordingly puts forward the policy system and guarantee measures for its improvement.
基金supported in part by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources(NRMSSHR2023Y02)Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes(PGPEC2304)+1 种基金Yunnan Normal University,China.This study was also sponsored by the Scientific Research Project of Education Department of Hubei Province(Grant No.B2022262)the Philosophy and Social Sciences Research Project of Education Department of Hubei Province(Grant No.22G024).
文摘The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.
基金supported by the Key Research and Development Program (Scientific and Technological Project)of Henan Province (Nos.212102310080,222102320294,and 232102231062)the Fundamental Research Funds for the Central Universities (No.220602024)the Major Focus Project of Henan Academy of Sciences (No.220102002)。
文摘This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312items kg^(-1)dry sediment across different survey stations,with an average abundance at(4388±713)items kg^(-1)dry sediment.Upon further categorization,it was found that transparent fragments were the primary color and type of microplastics present.The potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers studied.Cd was identified as the main potential ecological risk factor in the sediments of the studied areas.There was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage between these two environmental pollutants.However,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in sediments.In fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the sediments.This finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.
基金supported by Grants-in-Aid for Scientific Research of the Japanese Society for the Promotion of Science(JSPS KAKENHI)Grant Number 18H00766(principal investigator:Takashi Nakata)Grant Number 18KK0027(principal investigator:Yasuhiro Kumahara).
文摘The Arun and Tista Rivers,which flow across the Himalayas,are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges.To clarify whether the idea of antecedent rivers is acceptable,we investigated the geomorphology of the Himalayas between eastern Nepal and Bhutan Himalayas.The southern part of Tibetan Plateau,extending across the Himalayas as tectonically un-deformed glaciated terrain named as'Tibetan Corridor,'does not suggest the regional uplift of the Higher Himalayas.The 8,000-m class mountains of Everest,Makalu,and Kanchenjunga are isolated residual peaks on the glaciated terrain composed of mountain peaks of 4,000–6,000 m high.The Tibetan glaciers commonly beheaded by Himalayan glaciers along the great watershed of the Himalayas suggest the expansion of Himalayan river drainage by glaciation.For the narrow upstream regions of the Arun and Tista Rivers with less precipitation behind the range,it is hard to collect enough water for the power of down-cutting their channels against the uplifting Himalayas.The fission track ages of the Higher Himalayan Crystalline Nappe suggest that the Himalayas attained their present altitude by 11–10 Ma,and the Arun and Tista Rivers formed deep gorges across the Himalayas by headward erosion.
基金financially supported by the Postdoctoral Foundation of Qingdao(Pb Isotopes of Oujiang River to Quantitatively Identify Sediment Provenance in Oujiang Estuary and Adjacent Area)the China Geological Survey Project(No.DD20190276)the Fund of Ministry of Science and Technology(Nos.2013FY112200 and 2019YFE0127200).
文摘Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological environment of estuaries and bays.In order to investigate the seasonal characteristics of nutrients in small mountainous rivers in the subtropical monsoon region and the output pattern to the sea during heavy precipitation,surveys on the mountainous rivers were carried out in Baixi watershed in August 2020(wet season),March 2021(dry season)and June 2021(Meiyu period).The results showed that the dissolved inorganic nitrogen(DIN)of the rivers has an average concentration of 752μg L^(−1)in the wet season and 1472μg L^(−1)in the dry season.The concentrations of dissolved inorganic phosphorus(DIP)in wet season and dry season were 63μg L^(−1)and 51μg L^(−1),respectively.Influenced by the changes of land use in sub-watersheds,DIN concentrations in the mainstream increased from 701μg L^(−1)in the upper reaches to 1284μg L^(−1)in the middle reaches.Two rainstorms during the Meiyu period in the watershed caused the pulse runoff in the river.The maximum daily runoff reached 70 times that before rains.The maximum daily fluxes of DIN and DIP were 109 and 247 times that before rains,respectively.In view that the watershed experienced several rainstorms in the wet season,the river,with pulse runoff,carries a large amount of nutrients into the sea in a short time,which will have a significant impact on the environment of Sanmen bay and its adjacent sea.
基金supported by the Natural Science Foundation of Jiangsu Province,China(BK20220017)the Innovation Development Project of China Meteorological Administration(CXFZ2023J073)+1 种基金the Key Research and Development Program of Anhui Province,China(2022M07020003)the Graduate Student Practice and Innovation Program of Jiangsu Province,China(SJCX22_0374)。
文摘To understand the CH_(4) flux variations and their climatic drivers in the rice-wheat agroecosystem in the Huai River Basin of China,the CH_(4) flux was observed by using open-path eddy covariance at a typical rice-wheat rotation system in Anhui Province,China from November 2019 to October 2021.The variations and their drivers were then analyzed with the Akaike information criterion method.CH_(4) flux showed distinct diurnal variations with single peaks during 9:00-13:00 local time.The highest peak was 2.15μg m^(-2)s^(-1)which occurred at 11:00 in the vegetative growth stage in the rice growing season(RGS).CH_(4) flux also showed significant seasonal variations.The average CH_(4)flux in the vegetative growth stage in the RGS(193.8±74.2 mg m^(-2)d^(-1))was the highest among all growth stages.The annual total CH_(4) flux in the non-rice growing season(3.2 g m^(-2))was relatively small compared to that in the RGS(23.9 g m^(-2)).CH_(4) flux increased significantly with increase in air temperature,soil temperature,and soil water content in both the RGS and the non-RGS,while it decreased significantly with increase in vapor pressure deficit in the RGS.This study provided a comprehensive understanding of the CH_(4) flux and its drivers in the rice-wheat rotation agroecosystem in the Huai River Basin of China.In addition,our findings will be helpful for the validation and adjustment of the CH_(4) models in this region.
