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
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
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
Frequent flood disasters caused by climate change may lead to tremendous economic and human losses along inland waterways.Emergency response and rescue vessels(ERRVs)play an essential role in minimizing losses and pro...Frequent flood disasters caused by climate change may lead to tremendous economic and human losses along inland waterways.Emergency response and rescue vessels(ERRVs)play an essential role in minimizing losses and protecting lives and property.However,the path planning of ERRVs has mainly depended on expert experiences instead of rational decision making.This paper proposes an improved artificial potential field(APF)algorithm to optimize the shortest path for ERRVs in the rescue process.To verify the feasibility of the proposed model,eight tests were carried out in two water areas of the Yangtze River.The results showed that the improved APF algorithm was efficient with fewer iterations and that the response time of path planning was reduced to around eight seconds.The improved APF algorithm performed better in the ERRV’s goal achievement,compared with the traditional algorithm.The path planning method for ERRVs proposed in this paper has theoretical and practical value in flood relief.It can be applied in the emergency management of ERRVs to accelerate flood management efficiency and improve capacity to prevent,mitigate,and relieve flood disasters.展开更多
The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg...The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg/g with the change of depth,which was divided into three distribution types as follows:TN content decreases gradually with the increase of depth,TN content increases gradually with the increase of depth or higher content in the middle but lower content in two ends.NH4+-N content ranged from 8.7 ...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
[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a r...[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a research area through previous investigation, and the polluted river was cleaned and restored by 3 methods, i.e. artificial wetland, floating island type wetland and purification floating island. [Resuit] Floating plants （Hydrocotyle verticillata and Myriophyllum spicatum） showed better restoration effects than emergent aquatic plants （Iris wilsonii, Arundo donax, reed, water-cultured Ilex chinensis and Lythrum salicaria）. The two types of plants showed the removal rates of total nitrogen of 37.9% and 34.1%, respectively, the removal rates of total phosphorous of 80.1% and 73.5%, respectively, the removal rates of COD of 81.1% and 74.8%, respectively, the removal rates of ammonia nitrogen of 80.6% and 85.9%, respectively, and the removal rates of SS of 59.1% and 77.3%, respectively. Among the purification floating island, the artificial wetland and the floating island type wetland, the purification floating land restoration technique exhibited the best removal effect, with the removal rates of 87.6%, 71.3%, 87.6%, 97.5% and 81.8% for total nitrogen, total phosphorous, ammonia nitrogen COD and SS, respectively. The nitrification and denitdfication rates of bottom mud and water samples in the engineering segment were remarkably higher than those in the reference segment, by 15.4% and 21.1%, respectively. The nitrification and denitrification rates of bottom mud in the engineering segment and the non-engineering segment were higher than those of water samples by 26.9% and 31.8%, respectively. Restoration plants showed better removal effects of total phosphorous, total nitrogen, COD and SS under aeration condition than noeration condition. [Conclusion] The purification floating island has a significant restoration effect on urban polluted river.展开更多
Transboundary rivers,traversing multiple national borders,integrate sovereign states into a unified ecological system,complicating water resource governance amid rising global water scarcity and geopolitical tensions....Transboundary rivers,traversing multiple national borders,integrate sovereign states into a unified ecological system,complicating water resource governance amid rising global water scarcity and geopolitical tensions.Consequently,transboundary river governance exemplifies the public resource dilemma.This study,framed by constructivist international relations theory,examines the Lancang-Mekong River Basin as a case study,using data from multiple sources and socioeconomic indicators to explore the evolution of collective identity among riparian countries and its influencing factors.Key findings include:(1)The collective identity of riparian countries evolved in three phases:emergence(1971-1991),formation(1992-2014),and development(2015–2022).During this process,basin governance evolved from limited mechanisms to a more comprehensive,basin-wide system,with an expanded issue range and an increasing number of cooperation agreements.Cooperative attitudes transitioned from broadly positive to differentiated,ultimately aligning more favorably.(2)Economic interdependence is critical to the formation of collective identity among riparian countries,while diplomatic alignment enhances cooperation.(3)Extreme weather events and political globalization exert dual effects on collective identity formation:extreme weather fosters cooperation but also prioritizes domestic recovery,complicating agreements and expanding issues.Political globalization has facilitated institutionalization and normalization of cooperation,though external involvement has deepened divisions in cooperative attitudes.This study contributes to theoretical perspectives on transboundary river governance and supports collective action in global environmental governance.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
Dissolved organic matter(DOM)in rivers plays a key role in the global carbon cycle and aquatic ecosystems,yet its spatiotemporal dynamics across complex terrains remains inadequately characterized.To address this gap,...Dissolved organic matter(DOM)in rivers plays a key role in the global carbon cycle and aquatic ecosystems,yet its spatiotemporal dynamics across complex terrains remains inadequately characterized.To address this gap,we conducted seasonal sampling along the Luan River and examined how DOM composition varies over space and time in response to environmental drivers.Using parallel factor analysis(PARAFAC),we identified two humic-like components(C1+C2,Em>380 nm)and one protein-like component(C3,Em<380 nm).DOM fluorescence intensity was lowest in winter,while C1 and C3 levels peaked in autumn and C2 in summer(p<0.05).Spatially,C1 and C3 levels were highest downstream regions,whereas C2 peaked in the midstream section(p<0.05).Microbial sources dominated DOM in spring,winter,and in both headwater and downstream areas(FI>1.9).Principal coordinates analysis(PCoA)combined with multi-response permutation process(MRPP)confirmed significant spatiotemporal differences in DOM composition(p<0.05).Random forest modeling showed humic-like components were more sensitive to environmental changes.Redundancy analysis(RDA)and Mantel tests identified temperature as the dominant seasonal driver of DOM variation(p<0.05),while dissolved total phosphorus(DTP)and nitrate nitrogen(NO_(3)^(-)-N)were the key spatial determinants.Significant correlations were also observed between NO_(3)^(-)-N and ammonium nitrogen(NH_(4)^(+)-N),as well as between DTP and DOM,suggesting shared origins and compositional linkages(p<0.05).Our findings highlight the pronounced seasonal and spatial heterogeneity of DOM in multi-terrain river systems,offering valuable insights into carbon dynamics and ecosystem functioning in river systems.展开更多
The Changjiang River Estuary(CRE) and its offshore plumes host a diverse phytoplankton community;however, the spatiotemporal dynamics of these microorganisms and their environmental drivers remain poorly understood. T...The Changjiang River Estuary(CRE) and its offshore plumes host a diverse phytoplankton community;however, the spatiotemporal dynamics of these microorganisms and their environmental drivers remain poorly understood. This study aims to elucidate the spatiotemporal variations and environmental heterogeneity of phytoplankton communities in the CRE, as well as to understand the factors driving their assemblage. Utilizing ecological survey data collected from the CRE and adjacent waters during spring and summer from 2018 to 2020, we conducted a spatiotemporal analysis of phytoplankton β-diversity in the region. We decomposed β-diversity into species contributions to β-diversity(SCBD)and local contributions to β-diversity(LCBD) to examine spatial differences in phytoplankton diversity and the contributions of individual species within the community. Our findings reveal that spatial differences, primarily driven by water salinity and distance from the coastline, are key factors influencing the heterogeneity of phytoplankton community composition. Key species such as Skeletonema costatum, Melosira granulata, and M. granulata var.angustissima significantly affected β-diversity. Further, β-diversity decomposition reveals that community assembly is driven by interactive biogeochemical forces: salinity gradients shape spatial heterogeneity through runoff-seawater mixing, eutrophic conditions promote the dominance of nutrient-dependent taxa, and silica availability regulates diatom-to-flagellate succession. This study provides a methodological paradigm for analyzing phytoplankton community assembly mechanisms in estuaries, thereby offering scientific support for biogeography-based ecosystem management in the CRE.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
Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly...Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30 m wide and 0.4-7 m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450 m.展开更多
Water uses in small and middle-sized rivers, and non-ecological treatment model has deteriorated local environment in Shandong. The research reviewed ecological environment status quo of small and middle rivers and co...Water uses in small and middle-sized rivers, and non-ecological treatment model has deteriorated local environment in Shandong. The research reviewed ecological environment status quo of small and middle rivers and concluded existing problems. Finally, ecological treatments were proposed based on treatments at home and abroad in order to improve eco-environment of rivers and build better Shandong.展开更多
The 8th Intemational Riversymposium was held in Brisbane, Australia on 6-9 September 2005. The Intemational Riversymposium is an integral part of Brisbane＇s annual broadbased cultural event. The Queensland Government...The 8th Intemational Riversymposium was held in Brisbane, Australia on 6-9 September 2005. The Intemational Riversymposium is an integral part of Brisbane＇s annual broadbased cultural event. The Queensland Government is a foundation partner of the Intemational River Foundation, formed to secure the future of the Intemational and National Thiess Riverprize. The theme of symposium in this year is “Water and Food Security- Rivers in a Global Context” （ www.riversymposium.com ）. The Riversymposium provides a global forum which aims to make a difference to the declining state of rivers and waterways globally. Its strength lies in the breadth of its challenging program content of important keynote presentations and case studies of rivers in crisis, attracting a diverse range of national and intemational delegates. Some 450 scientists from 38 countries attended this conference, and about 100 papers were presented on the symposium in 2005.展开更多
Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine...Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine resources needed in river restoration programmes. We propose a conceptual riverscape model to rejuvenate the holy river Ganga in India through forestry interventions after due consideration of ecological processes, mosaic of landforms, communities and environment within the large landscape of Ganga basin. The select riverscape area includes the area of 5 km and 2 km on either side of the river Ganga and important tributaries, respectively, all along the rivers in five stakeholder states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, and West Bengal in the country. The width of the riverscape was taken from the maximum bank line in recent years on either side of river in the concerned state. However, all micro-watersheds in the hills of Uttarakhand state, being the origin place of river, have been included in riverscape area up to Haridwar. Here riverscape is a mosaic of different land uses viz., natural ecosystems, rural and agricultural ecosystems and built-up urban environment including flood plain and is an ecologically sustained system developed during the last 30 years due to river meandering all along the river. Geospatial modelling and GIS data on land use pattern, soil erosion rates, slope of the topography, etc. were used to classify riverscape area into high, medium and low priority areas to implement forestry interventions in delineated riverscape. Thereafter, forestry interventions were planned and carried out in three identified landscapes viz., Natural (forests), Agriculture (agroforestry), and Urban along with conservation activities. Forestry interventions in delineated riverscape are expected to increase water recharge<sup> </sup>and decrease the sedimentation load in the Ganga River and its tributaries.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The National Natural Science Foundation of China(Grant No.72274052)the National Natural Science Foundation of China(Grant No.72174173).
文摘Frequent flood disasters caused by climate change may lead to tremendous economic and human losses along inland waterways.Emergency response and rescue vessels(ERRVs)play an essential role in minimizing losses and protecting lives and property.However,the path planning of ERRVs has mainly depended on expert experiences instead of rational decision making.This paper proposes an improved artificial potential field(APF)algorithm to optimize the shortest path for ERRVs in the rescue process.To verify the feasibility of the proposed model,eight tests were carried out in two water areas of the Yangtze River.The results showed that the improved APF algorithm was efficient with fewer iterations and that the response time of path planning was reduced to around eight seconds.The improved APF algorithm performed better in the ERRV’s goal achievement,compared with the traditional algorithm.The path planning method for ERRVs proposed in this paper has theoretical and practical value in flood relief.It can be applied in the emergency management of ERRVs to accelerate flood management efficiency and improve capacity to prevent,mitigate,and relieve flood disasters.
基金Supported by Science and Technology Project from Jiangxi Provincial Department of Education(GJJ09430)International Scienceand Technology Cooperation Project(2006DFB91920)NationalKey Water Project(2008ZX07526-008)~~
文摘The vertical profile distribution characteristics of nitrogen in core sediments of Three Rivers Estuary in Poyang Lake were studied.The results showed that TN content in core sediments ranged from 480.0 to 1 900.0 μg/g with the change of depth,which was divided into three distribution types as follows:TN content decreases gradually with the increase of depth,TN content increases gradually with the increase of depth or higher content in the middle but lower content in two ends.NH4+-N content ranged from 8.7 ...
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.
文摘[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a research area through previous investigation, and the polluted river was cleaned and restored by 3 methods, i.e. artificial wetland, floating island type wetland and purification floating island. [Resuit] Floating plants （Hydrocotyle verticillata and Myriophyllum spicatum） showed better restoration effects than emergent aquatic plants （Iris wilsonii, Arundo donax, reed, water-cultured Ilex chinensis and Lythrum salicaria）. The two types of plants showed the removal rates of total nitrogen of 37.9% and 34.1%, respectively, the removal rates of total phosphorous of 80.1% and 73.5%, respectively, the removal rates of COD of 81.1% and 74.8%, respectively, the removal rates of ammonia nitrogen of 80.6% and 85.9%, respectively, and the removal rates of SS of 59.1% and 77.3%, respectively. Among the purification floating island, the artificial wetland and the floating island type wetland, the purification floating land restoration technique exhibited the best removal effect, with the removal rates of 87.6%, 71.3%, 87.6%, 97.5% and 81.8% for total nitrogen, total phosphorous, ammonia nitrogen COD and SS, respectively. The nitrification and denitdfication rates of bottom mud and water samples in the engineering segment were remarkably higher than those in the reference segment, by 15.4% and 21.1%, respectively. The nitrification and denitrification rates of bottom mud in the engineering segment and the non-engineering segment were higher than those of water samples by 26.9% and 31.8%, respectively. Restoration plants showed better removal effects of total phosphorous, total nitrogen, COD and SS under aeration condition than noeration condition. [Conclusion] The purification floating island has a significant restoration effect on urban polluted river.
基金National Science and Technology Support Program of China,No.2013BAB06B03National Key Research and Development Program of China,No.2016YFA0601600。
文摘Transboundary rivers,traversing multiple national borders,integrate sovereign states into a unified ecological system,complicating water resource governance amid rising global water scarcity and geopolitical tensions.Consequently,transboundary river governance exemplifies the public resource dilemma.This study,framed by constructivist international relations theory,examines the Lancang-Mekong River Basin as a case study,using data from multiple sources and socioeconomic indicators to explore the evolution of collective identity among riparian countries and its influencing factors.Key findings include:(1)The collective identity of riparian countries evolved in three phases:emergence(1971-1991),formation(1992-2014),and development(2015–2022).During this process,basin governance evolved from limited mechanisms to a more comprehensive,basin-wide system,with an expanded issue range and an increasing number of cooperation agreements.Cooperative attitudes transitioned from broadly positive to differentiated,ultimately aligning more favorably.(2)Economic interdependence is critical to the formation of collective identity among riparian countries,while diplomatic alignment enhances cooperation.(3)Extreme weather events and political globalization exert dual effects on collective identity formation:extreme weather fosters cooperation but also prioritizes domestic recovery,complicating agreements and expanding issues.Political globalization has facilitated institutionalization and normalization of cooperation,though external involvement has deepened divisions in cooperative attitudes.This study contributes to theoretical perspectives on transboundary river governance and supports collective action in global environmental governance.
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Basic Research Project of Universities in Hebei Province,Affiliated with Shijiazhuang City,Grant/Award Number:241791187ANatural Science Foundation of Hebei Province,Grant/Award Number:E2024208033+1 种基金Hebei Province graduate student innovation ability training program,Grant/Award Number:CXZZSS2025068Hebei Provincial Key Research Projects,Grant/Award Number:21373904D。
文摘Dissolved organic matter(DOM)in rivers plays a key role in the global carbon cycle and aquatic ecosystems,yet its spatiotemporal dynamics across complex terrains remains inadequately characterized.To address this gap,we conducted seasonal sampling along the Luan River and examined how DOM composition varies over space and time in response to environmental drivers.Using parallel factor analysis(PARAFAC),we identified two humic-like components(C1+C2,Em>380 nm)and one protein-like component(C3,Em<380 nm).DOM fluorescence intensity was lowest in winter,while C1 and C3 levels peaked in autumn and C2 in summer(p<0.05).Spatially,C1 and C3 levels were highest downstream regions,whereas C2 peaked in the midstream section(p<0.05).Microbial sources dominated DOM in spring,winter,and in both headwater and downstream areas(FI>1.9).Principal coordinates analysis(PCoA)combined with multi-response permutation process(MRPP)confirmed significant spatiotemporal differences in DOM composition(p<0.05).Random forest modeling showed humic-like components were more sensitive to environmental changes.Redundancy analysis(RDA)and Mantel tests identified temperature as the dominant seasonal driver of DOM variation(p<0.05),while dissolved total phosphorus(DTP)and nitrate nitrogen(NO_(3)^(-)-N)were the key spatial determinants.Significant correlations were also observed between NO_(3)^(-)-N and ammonium nitrogen(NH_(4)^(+)-N),as well as between DTP and DOM,suggesting shared origins and compositional linkages(p<0.05).Our findings highlight the pronounced seasonal and spatial heterogeneity of DOM in multi-terrain river systems,offering valuable insights into carbon dynamics and ecosystem functioning in river systems.
基金The program of opening ceremony to select the best candidates of the Key Laboratory of Marine Ecological Monitoring and Restoration Technologies,MNR under contract No. MEMRT2024JBGS01。
文摘The Changjiang River Estuary(CRE) and its offshore plumes host a diverse phytoplankton community;however, the spatiotemporal dynamics of these microorganisms and their environmental drivers remain poorly understood. This study aims to elucidate the spatiotemporal variations and environmental heterogeneity of phytoplankton communities in the CRE, as well as to understand the factors driving their assemblage. Utilizing ecological survey data collected from the CRE and adjacent waters during spring and summer from 2018 to 2020, we conducted a spatiotemporal analysis of phytoplankton β-diversity in the region. We decomposed β-diversity into species contributions to β-diversity(SCBD)and local contributions to β-diversity(LCBD) to examine spatial differences in phytoplankton diversity and the contributions of individual species within the community. Our findings reveal that spatial differences, primarily driven by water salinity and distance from the coastline, are key factors influencing the heterogeneity of phytoplankton community composition. Key species such as Skeletonema costatum, Melosira granulata, and M. granulata var.angustissima significantly affected β-diversity. Further, β-diversity decomposition reveals that community assembly is driven by interactive biogeochemical forces: salinity gradients shape spatial heterogeneity through runoff-seawater mixing, eutrophic conditions promote the dominance of nutrient-dependent taxa, and silica availability regulates diatom-to-flagellate succession. This study provides a methodological paradigm for analyzing phytoplankton community assembly mechanisms in estuaries, thereby offering scientific support for biogeography-based ecosystem management in the CRE.
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.
基金NSERC,Lithoprobe(Snorcle) and the Government of the Yukon for providing support for this research
文摘Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30 m wide and 0.4-7 m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450 m.
基金Supported by Shandong Province Soft Science Research Program(2015RKB01158)the Natural Science Foundation of Shandong Province(ZR2014DL002)Research Initiation Funds for the Introduced Talents in Taishan University(Y-01-2014019)~~
文摘Water uses in small and middle-sized rivers, and non-ecological treatment model has deteriorated local environment in Shandong. The research reviewed ecological environment status quo of small and middle rivers and concluded existing problems. Finally, ecological treatments were proposed based on treatments at home and abroad in order to improve eco-environment of rivers and build better Shandong.
文摘The 8th Intemational Riversymposium was held in Brisbane, Australia on 6-9 September 2005. The Intemational Riversymposium is an integral part of Brisbane＇s annual broadbased cultural event. The Queensland Government is a foundation partner of the Intemational River Foundation, formed to secure the future of the Intemational and National Thiess Riverprize. The theme of symposium in this year is “Water and Food Security- Rivers in a Global Context” （ www.riversymposium.com ）. The Riversymposium provides a global forum which aims to make a difference to the declining state of rivers and waterways globally. Its strength lies in the breadth of its challenging program content of important keynote presentations and case studies of rivers in crisis, attracting a diverse range of national and intemational delegates. Some 450 scientists from 38 countries attended this conference, and about 100 papers were presented on the symposium in 2005.
文摘Rivers have been degraded globally due to various reasons over centuries and limiting their ecological health and value, including Ganga River in India. Riverscape approach can provide relevant information on riverine resources needed in river restoration programmes. We propose a conceptual riverscape model to rejuvenate the holy river Ganga in India through forestry interventions after due consideration of ecological processes, mosaic of landforms, communities and environment within the large landscape of Ganga basin. The select riverscape area includes the area of 5 km and 2 km on either side of the river Ganga and important tributaries, respectively, all along the rivers in five stakeholder states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, and West Bengal in the country. The width of the riverscape was taken from the maximum bank line in recent years on either side of river in the concerned state. However, all micro-watersheds in the hills of Uttarakhand state, being the origin place of river, have been included in riverscape area up to Haridwar. Here riverscape is a mosaic of different land uses viz., natural ecosystems, rural and agricultural ecosystems and built-up urban environment including flood plain and is an ecologically sustained system developed during the last 30 years due to river meandering all along the river. Geospatial modelling and GIS data on land use pattern, soil erosion rates, slope of the topography, etc. were used to classify riverscape area into high, medium and low priority areas to implement forestry interventions in delineated riverscape. Thereafter, forestry interventions were planned and carried out in three identified landscapes viz., Natural (forests), Agriculture (agroforestry), and Urban along with conservation activities. Forestry interventions in delineated riverscape are expected to increase water recharge<sup> </sup>and decrease the sedimentation load in the Ganga River and its tributaries.
