Research into the location and development of rice paddies after the collapse of Neolithic cultures is of crucial importance.This study explores the phytolith assemblages and soil micromorphologies of potential rice p...Research into the location and development of rice paddies after the collapse of Neolithic cultures is of crucial importance.This study explores the phytolith assemblages and soil micromorphologies of potential rice paddy relics found at the Xingang Site(3556–3360 cal.a BP)in the Taihu Lake Plain,Lower Yangtze River,offering insights into these issues.The discriminant function of the phytolith assemblage distinguished six out of 19 samples in the suspected paddy field area as wild rice fields,while the rest were non-rice fields.Soil micromorphology indicated that the alleged paddy field area experienced repeated dry and wet conditions,with signs of plant growth but no evidence of human activity,suggesting it was not an artificially managed paddy field.These findings suggest the area during the Shang Dynasty consisted of abandoned paddies from the post-Neolithic era.The proportion of rice bulliform phytoliths with≥9 fish-scale decorations(35%–47%)was significantly lower at the Xingang Site(marginal area)during the Shang Dynasty compared to periods like Qianshanyang-Guangfulin(4300–3900 a BP)(central area),suggesting that diminished population density in marginal areas after the Neolithic collapse likely led to paddy field abandonment.Additionally,the collapse of the Liangzhu social structure,along with a rice-farming economy that lacked strong resource competitiveness,may have also contributed to this phenomenon.This study provides an empirical example of rice paddy locations following the Neolithic collapse in the Lower Yangtze River,enhancing our understanding of the decline of the Liangzhu civilization.展开更多
Decades of species composition changes can lead to the eutrophication-driven loss of submerged macrophytes in shallow lakes.Investigating the mechanisms of these nature-and human driven changes is crucial for the rest...Decades of species composition changes can lead to the eutrophication-driven loss of submerged macrophytes in shallow lakes.Investigating the mechanisms of these nature-and human driven changes is crucial for the restoration and management of such lakes.To investigate the changes in aquatic macrophyte communities over the past two centuries,we analyzed macrofossils in sediments from a^(210)Pb-dated core obtained in Dongping Lake in the lower Huanghe(Yellow)River Basin,eastern China.Multiple factor analysis(MFA)revealed an association between macrophyte shifts and changes in various environmental stressors(invertebrates,grain size,geochemistry,and documented records),indicating that macrophyte community changes before 1960 were predominately driven by flood disturbances.Ever since,anthropogenic pollution and the construction of water conservancy projects have caused variations in hydrology and nutrients,leading to significant changes in the composition of macrophyte communities.Macrofossil data reveal a decline in diversity and pollution-intolerant species during the late 1980 s and the early 2000 s,which is indicative of eutrophication.We also found that the current environment of Dongping Lake exhibits a clear degeneration in emergent plants and a proliferation of macrophyte species associated with eutrophic conditions,which could be attributed to water level fluctuation and nutrient input due to the water supply from the eastern route of the South-to-North Water Diversion Project as well as climate warming.Our results provide valuable insights for assessing ecosystem health and the restoration and management of Dongping Lake and similar lakes in the Huanghe River region and elsewhere.展开更多
Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophica...Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophication ecological risk.Taihu Lake is a typical eutrophic shallowlake,suffering fromcyanobacteria blooms for decades due to excessive exogenous nutrient load.In this study,the coupling relationship between basin N loss and lake responsewas established by combining N flow and exogenous nutrient load.The results showed striking spatiotemporal differences and the large tributaries input themajority of N.Three evolution stages of the lake ecosystem were classified,i.e.,Stage A(1980–1997)with slow increasing N load;Stage B(1998–2006)with high-level N load despite some controlling methods;Stage C(2007 to present)with the strengthening of N management in lake basin after the Water Crisis,the N load has gradually decreased,while the water flow is increasing by the year.Environmental N export in the basin was 581.46 kg/ha N in 2021,and a total of 32.06 Gg N was finally drawn into the lake.Over the recent two decades,the noticeable expansion of built-up land from 8.21%to 21.04%associated with its environmental impacts i.e.,urban heat island effect,hard pavement,and ecological fragility deserves attention.Accordingly,the rapid climate change of the basin became the key factor driving the tributaries’hydrologic conditions(r_(∂)=0.945).The developed social economy dominated the sewage discharge(r_(∂)=0.857).The N inputs and losses to the environment in the basin can be further exacerbated without control.Meanwhile,the lake would respond to the exogenous input.In addition to the self-cleaning part of the lake,the N accumulation rate of the surface sediment ranged from 3.29 to 10.77 g N/(m^(2)·yr)of Taihu Lake.To meet the pollutant control target,around 66.28 Gg anthropogenic N needs to be reduced in the upper stream area yearly.Clarifying the N flow and its environmental burden can mitigate its damage to the ecosystem and take on the refined management on the watershed scale.展开更多
Biological nitrogen fixation(BNF)is a crucial process that provides bioavailable nitrogen and supports primary production in freshwater lake ecosystems.However,the characteristics of diazotrophic community and nitroge...Biological nitrogen fixation(BNF)is a crucial process that provides bioavailable nitrogen and supports primary production in freshwater lake ecosystems.However,the characteristics of diazotrophic community and nitrogenase activity in freshwater lake sediments remain poorly understood.Here,we investigated the diazotrophic communities and nitrogenase activities in the sediments of three large river-connected freshwater lakes in eastern China using 15N-isotope tracing and nifH sequencing.The sediments in these lakes contained diverse nitrogenase genes that were phylogenetically grouped into Clusters I and III.The diazotrophic communities in the sedimentswere dominated by stochastic processes in Hongze Lake and Taihu Lake,which had heterogeneous habitats and shallower water depths,while in Poyang Lake,which had deeper water and a shorter hydraulic retention time,the assembly of the diazotrophic community in the sediments was dominated by homogeneous selection processes.Temperature and water depth were also found the key environmental factors affecting the sediment diazotrophic communities.Sediment nitrogenase activities varied in the three lakes and within distinct regions of an individual lake,ranging from 0 to 14.58 nmol/(kg·hr).Nitrogenase activity was significantly correlated with ferric iron,total phosphorus,and organic matter contents.Our results suggested that freshwater lake sediment contain high diversity of nitrogen-fixing microorganisms with potential metabolic diversity,and the community assembly patterns and nitrogenase activities varied with the lake habitat.展开更多
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
Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem ...Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem has been increasingly degraded,especially with the frequent cyanobacteria blooms,which directly threatens the maintenance of ecosystem service function and sustainable urban development.In this study,several sedimentary cores were collected from Hudie Lake located in the Yangtze River Delta in China that had not been dredged for centuries.Using one of the sediment cores that spans the past 200 years,we reconstructed the long-term environmental changes and examined the driving mechanisms of both human activities and natural factors affecting the lake's dynamics.Our results indicated that,with the growth of the city,organic matter and nutrients in the lake had gradually increased.Notably,the significant increase in phosphorus had been a key factor driving cyanobacteria blooms in Hudie Lake.Since the 1960s,urban development and changes in land use around the lake had severely disturbed its natural habitats,leading to peak nutrient levels during the period from 2000 to 2010.展开更多
Shallow lakes of the middle-lower reaches of Changjiang(Yangtze)River are a globally unique ecosystem essential for the regional sustainable economic development.These lakes have recently been under pressure from both...Shallow lakes of the middle-lower reaches of Changjiang(Yangtze)River are a globally unique ecosystem essential for the regional sustainable economic development.These lakes have recently been under pressure from both human activities and climate change,underscoring the need for research on their ecological health and drivers.However,most previous studies focused on large lakes(i.e.,over 500 km^(2))and limited ecological elements,such as nutrient levels.Caizi Lake,a relatively small(approximately 226 km^(2)),a Changjiang River-isolated shallow lake,was chosen as a case of study.We assessed its ecological health and analyzed the driving forces using an integrated dataset from in situ observations,remote sensing,and historical data.Our findings indicate that in 2023,the mean ecological health score,reflecting from all selected elements—algal bloom area,zooplankton,macroinvertebrates,macrophytes coverage,comprehensive trophic level index,and biodiversity—was 50.4 out of the maximum of 100.Notably,the ecological health scores for macrophytes coverage(1.9),macroinvertebrates(17.2),and biodiversity(44.0)were particularly low.In 1960–2007,the ecological health was deteriorated as the macrophytes coverage was dropped from 80%to 50%.The degradation of macroinvertebrate communities and a decrease in biodiversity might be primarily due to the eutrophication-induced abnormal algal proliferation.In 2007–2023,elevated water levels might degrade the macrophytes coverage and other aspects of ecological health.Therefore,we proposed an ecological health restoration plan for Caizi Lake focusing on nutrient reduction and water level regulation on the thresholds of total nitrogen and phosphorus concentrations,an and provided a reference for the protection of Caizi Lake and other cases having similar hydromorphic background.展开更多
The study of ecological water demand in rivers has been a research hotspot in recent years.In this paper,selecting the widely used research methods(Tennant method,minimum monthly flow average measurement method,monthl...The study of ecological water demand in rivers has been a research hotspot in recent years.In this paper,selecting the widely used research methods(Tennant method,minimum monthly flow average measurement method,monthly average flow guarantee rate method,monthly minimum flow method,7Q 10 improvement method),the ecological water demand of rivers in the Dongting Lake basin was studied.Combined with the hydrological characteristics of the basin water system,the calculation results by the above five methods were averaged.It was obtained that the ecological water demand of rivers in the basin from April to September and from October to next March was 3.876×10^(9) and 3.425×10^(9) m^(3),respectively.The annual ecological water demand was 7.301×10^(9) m^(3),accounting for about 11.46%of the average annual runoff in the basin.The research results can provide a basis for regional water resource utilization planning and are of great significance for maintaining the health of river ecosystems.展开更多
High-altitude glacier-lake systems in the eastern Pamir Plateau,Tajikistan,are highly sensitive elements of Central Asia’s cryosphere and are vital for sustaining regional water resources.The Yashilkul Lake is locate...High-altitude glacier-lake systems in the eastern Pamir Plateau,Tajikistan,are highly sensitive elements of Central Asia’s cryosphere and are vital for sustaining regional water resources.The Yashilkul Lake is located within a tectonic depression dammed by an ancient rockslide,forming a large alpine lake.This lake is currently impacted by intensified warming,glacier retreat,and poorly quantified hydrological shift.The primary objective of this study is to assess multi-decadal changes in the Yashilkul and Bulunkul lakes and their surrounding cryosphere between 1994 and 2024.The changes were analyzed using multitemporal Landsat imagery and unmanned aerial vehicle (UAV) surveys,complemented by in situ meteorological observations from the Bulunkul meteorological station spanning the period from 1990 to 2024.Glacier and lake boundaries were extracted from Landsat data,primarily by applying the normalized difference water index,supplemented by manual delineation.UAV photogrammetry characterized dam morphology and adjacent ponds,and climate trends were evaluated with the modified Mann-Kendall test.A significant warming trend of 0.096℃/a and pronounced interannual precipitation variability have driven persistent glacier retreat and lake surface area fluctuations.The Yashilkul Lake’s surface area decreased from 36.40 (±1.15) km^(2) in 2010 to 31.94 (±0.54) km^(2) in 2020 and partially rebounded to 33.99 (±0.60) km^(2) in 2024,while the Bulunkul Lake’s surface area remained nearly stable owing to limited glacial influence.Additionally,UAV surveys conducted in 2022 and 2024 revealed main features of the Yashilkul Lake:rockslidedammed origin,perched ponds along the dam body,and an artificial canal regulating its outflow.Nearby glaciers,particularly Glacier No.369,exhibited strong frontal retreat and proglacial lake expansion.The proglacial lake expanded nearly fourfold from 0.08 (±0.01)km^(2) in 2000 to 0.33 (±0.02) km^(2) in 2024,raising concerns about potential glacial lake outburst floods that could impact the Yashilkul Lake and compromise the integrity of its natural dam.The findings highlight accelerating hydrological and cryospheric transformations in the Pamir Plateau,emphasizing the need for sustained monitoring of glacier-lake systems owing to their critical implications for water security,ecological stability,and downstream hazard management.展开更多
Antibiotics are widespread in aquatic environments due to their extensive use in human healthcare and ani-mal husbandry.However,research on the occurrence and bioaccumulation of antibiotics in aquatic organisms within...Antibiotics are widespread in aquatic environments due to their extensive use in human healthcare and ani-mal husbandry.However,research on the occurrence and bioaccumulation of antibiotics in aquatic organisms within shallow wetland lakes remains limited.This study investigated the occurrence and bioaccumulation of ten commonly used antibiotics in the Baiyang Lake,northern China’s largest shallow wetland lake.The results indicated that sulfonamides and fluoroquinolones were the predominant antibiotics in surface water,whereas fluoroquinolones and macrolides were more prevalent in sediment.Fluoroquinolones demonstrated significant potential for bioaccumulation in targeted aquatic organisms,including both animals and plants(Carassius au-ratus and Phragmites australis).The bioaccumulation of antibiotics in Carassius auratus was correlated with their solubility,whereas in Phragmites australis,this was associated with their octanol-water partition coefficients and molecular weights.Ecological risk assessment indicated that most antibiotics posed minimal to low risk levels.However,four antibiotics were exceptions:clarithromycin(12.5%)and sulfamethoxazole(6.25%)presented a high risk in surface water samples,while norfloxacin(25.0%)and ciprofloxacin(25.0%)posed a high risk in sediment samples.Norfloxacin,ciprofloxacin,and roxithromycin were identified as key indicator antibiotics for enhancing the local monitoring and control of antibiotic contamination based on four criteria:(1)high con-centrations,(2)frequent detection,(3)capacity for bioaccumulation,and(4)ecological risk levels.This study contributes to a deeper understanding of the status of antibiotic contamination,bioaccumulation characteristics,and ecological risk in Baiyang Lake,thereby supporting efforts to monitor and regulate antibiotic pollution.展开更多
This study investigates the potential formation of subglacial lakes beneath the glaciers of the Franz Josef Land archipelago,Russian Arctic,under current and future climatic conditions.Using a one-dimensional heat and...This study investigates the potential formation of subglacial lakes beneath the glaciers of the Franz Josef Land archipelago,Russian Arctic,under current and future climatic conditions.Using a one-dimensional heat and mass transfer model,the research evaluates the influence of geothermal heat flow,ice thickness,and surface temperature on basal melting.The model incorporates enthalpy formulation and boundary conditions derived from field data,including temperature profiles and geothermal measurements.Results indicate that subglacial lakes could form under ice masses exceeding 300 m thickness,driven by geothermal heating,though current basal temperatures remain below the melting point.Simulations under the IPCC SSP1-2.6 scenario suggest a gradual warming trend,highlighting the long-term thermal inertia of Arctic glaciers.The study underscores the need for enhanced observational data to validate models and improve predictions of glacial dynamics in response to climate change.展开更多
While oceanic and coastal acidification has gained increased attention,long-term pH trends and their drivers in large freshwater systems remain poorly understood.The Laurentian Great Lakes are the world’s largest fre...While oceanic and coastal acidification has gained increased attention,long-term pH trends and their drivers in large freshwater systems remain poorly understood.The Laurentian Great Lakes are the world’s largest freshwater system,and in many ways resemble marine ecosystems.However,unlike the open ocean and coastal waters where pH has declined due to rising atmospheric CO_(2),no significant pH trends have been observed in the Laurentian Great Lakes,despite significant ecosystem changes driven partly by the invasion of dreissenid mussels.This study examined 41 years of field observations from Lake Michigan to investigate the long-term carbonate chemistry dynamics.Observational results revealed substantial declines in both total alkalinity(TA)and dissolved inorganic carbon(DIC)over the four decades.Mussel shell calcification emerged as the primary mechanism behind these declines,accounting for 97%and 47%of the observed changes in TA and DIC,respectively,lowering water column pH by 0.24 units.Elevated carbon accumulation in soft mussel tissues,coupled with long-term changes in the air-water pCO_(2)gradient during summer,significantly contributed to long-term DIC variations,explaining 18%and 28%of the lake-wide DIC loss.These two mechanisms also resulted in an overall pH increase of 0.09 and 0.12 units,largely offsetting the calcification-driven pH decrease.These findings bridge a gap in acidification research for large freshwater systems and provide valuable insights for comprehensive lake-wide management strategies.展开更多
Lakes are carbon dioxide(CO_(2))and methane(CH_(4))emission hotspots,whose associated flux is spatially vari-able.Many studies have investigated the impact of microorganisms and environmental factors on CO_(2) and CH_...Lakes are carbon dioxide(CO_(2))and methane(CH_(4))emission hotspots,whose associated flux is spatially vari-able.Many studies have investigated the impact of microorganisms and environmental factors on CO_(2) and CH_(4) emissions between different lakes.However,the carbon emissions and their influencing factors of different areas within a single lake remain poorly understood.Accordingly,this study investigates CO_(2) and CH_(4) emission hetero-geneity in a large floodplain lake system and distribution characteristics of associated functional microorganisms.Findings show that mean CO_(2) and CH_(4) flux values in the sub lake area were 62.03±24.21 mg/(m2·day)and 5.97±3.2μg/(m2·day),which were greater by factors of 1.78 and 2.96 compared to the water channel and the main lake area,respectively.The alpha diversity of methanogens in the sub lake area was lower than that in the main lake and water channel areas.The abundance of methanogens in bottom water layer was higher compared with the middle and surface layers.Conversely,the abundance of methane(CH_(4))-oxidizing bacteria in the surface layer was higher than that in the bottom layer.Additionally,the composition of methanogen and CH_(4)-oxidizing bacterial community,chlorophyll a(Chl-a),pH,total phosphorus(TP)and dissolved organic carbon(DOC)con-tent constituted the dominate driving factors affecting lake C emissions.Results from this study can be used to improve our understanding of lake spatial heterogeneous of CO_(2) and CH_(4) emission and the driving mechanisms within floodplain lakes under the coupling effects of functional C microorganisms and environmental factors.展开更多
Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(AC...Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(ACA)region.However,debate persists regarding whether dryland lakes in this region exhibited aridification or humidification during the Holocene.Lopnur serves as the terminal lake of Tarim rivers during the Holocene,which offers an ideal natural laboratory to address the questions.In this study,a high-resolution chronological framework was established through precise radiocarbon dating.Multi-proxy analyses,including geochemical composition,grain size distributions,MS,LOI,and C/N ratios were conducted from a lacustrine profile in the core area of“Great ear”in the southern part of Lopnur catchment.These analyses enabled the reconstruction of hydrological dynamics and facilitated the disentanglement of independent signals linked to climate variability,runoff fluctuations,and lake-level changes.The results demonstrate that the MidHolocene(7800–4000 cal yr B.P.)was characterized by cold and humid conditions,resulting in elevated surface runoff and lake level.The Late Holocene(4000–1300 cal yr B.P.)experienced intensified aridification,characterized by reduced runoff and declining lake level.These evidences suggested a climatic regime of a distinctive alternation between“cold-wet”and“warm-dry”climatic regimes during the Mid-to-Late Holocene.Compared with the previous studies from adjacent regions,we speculate that the hydroclimatic evolution of Lopnur catchment possibly influenced by a complex interplay of large spatial scale forcings,including variations in annual insolation,greenhouse gas concentrations,and ice sheets,as well as the localized controls such as topographic features,vegetation cover,and cloud-radiative feedbacks.Our findings enhance the understanding of past climatic complexity and provide valuable insights for future water resource management strategies in drylands.展开更多
Nitrate pollution is a severe threat to the fragile ecosystems in karst regions.However,our knowledge of the sources and transformations of nitrate in karst cave groundwater is still limited.This study aimed to invest...Nitrate pollution is a severe threat to the fragile ecosystems in karst regions.However,our knowledge of the sources and transformations of nitrate in karst cave groundwater is still limited.This study aimed to investigate the temporal and spatial patterns of nitrate dynamics in the underground water of karst caves located on the south bank of the Qingjiang River in central China,through a comprehensive application of multiple approaches,such as hydrochemistry,nitrogen and oxygen isotope compositions of nitrate,and a Bayesian isotope mixing model(SIMMR).During the sampling period(from December 2018 to December 2019),the nitrate concentration did not show an apparent temporal variation;meanwhile,no water samples in this study had a nitrate concentration higher than the limit for drinking water,but the nitrate concentration in karst underground rivers is significantly higher than that in surface water.The results of the comprehensive analyses revealed that the predominant nitrate sources included nitrification in soil and chemical fertilizer,which had mean percentages of 43%and 32%,respectively.The source contribution varied in the outlet water among different caves.The soil-derived nitrate in the underground water from the Shizi Cave accounted for the highest proportion(49%),while chemical-fertilizer-derived nitrate in the underground water from the Mishui Cave accounted for the highest proportion(36%).The dualisotope signatures of nitrate supported a major influence on nitrogen dynamics in the cave underground from nitrification.These findings suggest that nitrate carried by underground rivers in karst caves should be alerted when making the nitrate balance in rivers flowing through karst areas.展开更多
Understanding water chemistry in karst regions is crucial for improving global water resource management and deepening our knowledge of the biogeochemical cycles shaping these sensitive environments.Despite advance-me...Understanding water chemistry in karst regions is crucial for improving global water resource management and deepening our knowledge of the biogeochemical cycles shaping these sensitive environments.Despite advance-ments in karst hydrology,significant gaps remain in long-term trends,underlying processes,and quantitative effects of environmental changes.This is especially true in areas like the Wujiang River(WJ)in China,where human activities such as reservoir construction and land use/cover changes have accelerated hydrochemical changes.We combined recent and historical monitoring data to provide a detailed analysis of the spatial and temporal characteristics,evolution,and controlling factors of major ions in WJ.These findings are important for local water management and contribute to global efforts to manage similar karst systems facing human-induced pressures.Our research shows clear seasonal differences in solute concentrations,with higher levels during the dry season.WJ’s water is rich in calcium,with Ca-HCO_(3) ion pairs being the most common.Reservoir monitor-ing stations show much higher levels of NO_(3)^(−)and SO_(4)^(2−)compared to river-type stations,likely due to longer hydraulic retention time and increased acid deposition.The study confirms the significant role of pH and water temperature in rock weathering processes.Land use/cover changes were identified as the primary drivers of solute variations(46.37%),followed by lithology(13.92%)and temperature(8.35%).Over the past two decades,in-tense carbonate weathering has been observed,especially during wet seasons.Among karstic provinces,Guizhou Province stands out with the highest ion concentrations,indicative of its extensive karst coverage and heightened weathering processes.展开更多
Aquatic plants have been widely used for lake ecological restoration.The effect of aquatic plants on lake biogeochemical cycling has been investigated intensively,however,plants’effect on biodegradation of dissolved ...Aquatic plants have been widely used for lake ecological restoration.The effect of aquatic plants on lake biogeochemical cycling has been investigated intensively,however,plants’effect on biodegradation of dissolved organic carbon(DOC)is rarely studied.Here we designed an indoor incubation experiment to explore the priming effect(PE)of aquatic plant leaching solution on DOC in shallow lakes,referring to as the input of active dissolved organic matter(DOM)that would arouse changes in the degradation rate of original refractory DOM.Waters from 20 urban lakes of different tropic states were incubated to study their PE on DOC by adding leaching solutions from two submerged freshwater plants,Hydrilla(H)and Vallisneria(V).The study showed a clear influence of aquatic plants on PE with varying directions and intensities.The H incubation group showed a PE range of-6.19%–9.79%,with an average of 2.15%±2.70%,whereas the V incubation group exhibited a PE range of-10.03%to 3.60%,with an average of-0.65%±3.11%.The positive and negative PEs by the two plant species indicate a key role of plants over trophic states on organic carbon dynamics in freshwater lakes.From the perspective of plant leaching input,our results reveal that planting aquatic plants whose leaching solution can reduce PE like V could be used to enhance carbon storage and constrain carbon emission.展开更多
Major chemical ionic components in water serve as indicators of natural factors in the areas traversed by water bodies,and are thus widely used to elucidate key hydrogeochemical processes,including rock weathering,aqu...Major chemical ionic components in water serve as indicators of natural factors in the areas traversed by water bodies,and are thus widely used to elucidate key hydrogeochemical processes,including rock weathering,aquatic evaporation-crystallization,and the input of precipitation-derived materials into river basins.A total of 208 water samples were collected between August 2021 and August 2022 to investigate the hydrochemical characteristics and their influencing factors of the surface water and the groundwater in the Mingyong River Basin.To systematically analyze the data,we combined hydrogeochemical and statistical methods:descriptive statistics characterized ion concentration and physicochemical parameter distributions;Piper trilinear diagrams classified hydrochemical types;Pearson correlation analysis assessed ion-ion and ionTDS dependencies;Gibbs diagrams and ion ratio analysis identified solute sources;and the absolute principal component score-multiple linear regression(APCS-MLR)model quantified the contribution rates of different influencing factors.The results revealed that the dominant cations in the surface water and groundwater are Ca^(2+)and Mg^(2+),while the dominant anions are HCO_(3)^(-)and SO_(4)^(2-).The groundwater exhibits an extended residence time within rock strata,facilitating prolonged interaction with soluble minerals and intensifying the water-rock reaction process,thereby resulting in higher levels of electrical conductivity(EC),pH,and total dissolved solids(TDS)than those in the surface water.Secondly,the parameters of the surface water and groundwater indicate positive correlation.The weathering of rocks constitutes the primary solute source in the water of the basin.The hydrochemical composition of the basin water is primarily influenced by both carbonate and silicate rocks,with a minor contribution from evaporite rocks.The water bodies in the basin are affected by anthropogenic activities.The surface water is influenced by four sources,namely lixiviation-enrich,human activities,geological environmental,and unknown sources.The groundwater is influenced by five sources,namely lixiviation-enrich,primary geological,human activities,geological environmental,and unknown sources.展开更多
Effective conservation relies on robust assessments;however,the lack of waterbird data in the Yellow River Basin(YRB)has led to an underestimation of key habitat significance.This study addressed this gap by evaluatin...Effective conservation relies on robust assessments;however,the lack of waterbird data in the Yellow River Basin(YRB)has led to an underestimation of key habitat significance.This study addressed this gap by evaluating YRB wetland conservation importance using waterbirds as indicators and applying Ramsar,Important Bird Areas(IBA),and East Asian-Australasian Flyway(EAAF)criteria.We integrated coordinated surveys with citizen science data,creating a framework that tackles data deficiencies along the under-monitored Central Asian Flyway(CAF).Our analysis identified 75 priority wetlands,supporting 15 threatened species and 49 exceeding global/flyway 1%thresholds,highlighting the basin's biodiversity.We observed strong seasonal habitat use,with high-altitude wetlands vital for breeding and migration,and the Yellow River Delta providing year-round refuge.This research also provided data to refine Baer's Pochard population estimates.Alarmingly,one-third of the identified priority areas,primarily rivers and lakes,remain unprotected.To address this,we recommend systematic surveys,enhanced protected areas,OECMs,and targeted wetland restoration.This study underscores the YRB's role in regional conservation and provides essential data for adaptive management,particularly emphasizing the CAF's importance.展开更多
基金The Archaeological Talent Promotion Program of China(2024-272)National Natural Science Foundation of China No.42301173,No.42101152+5 种基金Natural Science Foundation of Jiangsu Province,China,No.BK20230386,No.BK20221027Humanities and Social Science Fund of Ministry of Education of China,No.23YJCZH096The Fundamental Research Funds for the Central Universities,No.SKCX2024011,No.SKYZ2024026Key Project of Higher Education Teaching Reform Research and Practice in Henan Province,No.2024 SJGLX0209Humanities and Social Sciences Prestigious Fellowship Scheme,University Grants Committee,Hong Kong,No.34000323Comprehensive Research Project on Scientific and Technological Archaeology of Changzhou City’s Daxujiacun Site and Chuanfangtou Site(Phase III),No.JSZC-320400-FW2025-06406。
文摘Research into the location and development of rice paddies after the collapse of Neolithic cultures is of crucial importance.This study explores the phytolith assemblages and soil micromorphologies of potential rice paddy relics found at the Xingang Site(3556–3360 cal.a BP)in the Taihu Lake Plain,Lower Yangtze River,offering insights into these issues.The discriminant function of the phytolith assemblage distinguished six out of 19 samples in the suspected paddy field area as wild rice fields,while the rest were non-rice fields.Soil micromorphology indicated that the alleged paddy field area experienced repeated dry and wet conditions,with signs of plant growth but no evidence of human activity,suggesting it was not an artificially managed paddy field.These findings suggest the area during the Shang Dynasty consisted of abandoned paddies from the post-Neolithic era.The proportion of rice bulliform phytoliths with≥9 fish-scale decorations(35%–47%)was significantly lower at the Xingang Site(marginal area)during the Shang Dynasty compared to periods like Qianshanyang-Guangfulin(4300–3900 a BP)(central area),suggesting that diminished population density in marginal areas after the Neolithic collapse likely led to paddy field abandonment.Additionally,the collapse of the Liangzhu social structure,along with a rice-farming economy that lacked strong resource competitiveness,may have also contributed to this phenomenon.This study provides an empirical example of rice paddy locations following the Neolithic collapse in the Lower Yangtze River,enhancing our understanding of the decline of the Liangzhu civilization.
基金Supported by the National Natural Science Foundation of China(Nos.42007397,41871073)the Natural Science Foundation of Shandong Province(No.ZR2020QD002)。
文摘Decades of species composition changes can lead to the eutrophication-driven loss of submerged macrophytes in shallow lakes.Investigating the mechanisms of these nature-and human driven changes is crucial for the restoration and management of such lakes.To investigate the changes in aquatic macrophyte communities over the past two centuries,we analyzed macrofossils in sediments from a^(210)Pb-dated core obtained in Dongping Lake in the lower Huanghe(Yellow)River Basin,eastern China.Multiple factor analysis(MFA)revealed an association between macrophyte shifts and changes in various environmental stressors(invertebrates,grain size,geochemistry,and documented records),indicating that macrophyte community changes before 1960 were predominately driven by flood disturbances.Ever since,anthropogenic pollution and the construction of water conservancy projects have caused variations in hydrology and nutrients,leading to significant changes in the composition of macrophyte communities.Macrofossil data reveal a decline in diversity and pollution-intolerant species during the late 1980 s and the early 2000 s,which is indicative of eutrophication.We also found that the current environment of Dongping Lake exhibits a clear degeneration in emergent plants and a proliferation of macrophyte species associated with eutrophic conditions,which could be attributed to water level fluctuation and nutrient input due to the water supply from the eastern route of the South-to-North Water Diversion Project as well as climate warming.Our results provide valuable insights for assessing ecosystem health and the restoration and management of Dongping Lake and similar lakes in the Huanghe River region and elsewhere.
基金supported by the National Key Research and Development Program of China(No.2021YFC3201502)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_1830).
文摘Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophication ecological risk.Taihu Lake is a typical eutrophic shallowlake,suffering fromcyanobacteria blooms for decades due to excessive exogenous nutrient load.In this study,the coupling relationship between basin N loss and lake responsewas established by combining N flow and exogenous nutrient load.The results showed striking spatiotemporal differences and the large tributaries input themajority of N.Three evolution stages of the lake ecosystem were classified,i.e.,Stage A(1980–1997)with slow increasing N load;Stage B(1998–2006)with high-level N load despite some controlling methods;Stage C(2007 to present)with the strengthening of N management in lake basin after the Water Crisis,the N load has gradually decreased,while the water flow is increasing by the year.Environmental N export in the basin was 581.46 kg/ha N in 2021,and a total of 32.06 Gg N was finally drawn into the lake.Over the recent two decades,the noticeable expansion of built-up land from 8.21%to 21.04%associated with its environmental impacts i.e.,urban heat island effect,hard pavement,and ecological fragility deserves attention.Accordingly,the rapid climate change of the basin became the key factor driving the tributaries’hydrologic conditions(r_(∂)=0.945).The developed social economy dominated the sewage discharge(r_(∂)=0.857).The N inputs and losses to the environment in the basin can be further exacerbated without control.Meanwhile,the lake would respond to the exogenous input.In addition to the self-cleaning part of the lake,the N accumulation rate of the surface sediment ranged from 3.29 to 10.77 g N/(m^(2)·yr)of Taihu Lake.To meet the pollutant control target,around 66.28 Gg anthropogenic N needs to be reduced in the upper stream area yearly.Clarifying the N flow and its environmental burden can mitigate its damage to the ecosystem and take on the refined management on the watershed scale.
基金supported by the National Natural Science Foundation of China(Nos.51839011,42203079,and U2240208)the Carbon Peak/Neutralization Technology Innovation Project of Jiangsu Province,China(No.BK20220043)the Excellent Postdoctoral Project of Jiangsu Province,China(No.2022ZB452).
文摘Biological nitrogen fixation(BNF)is a crucial process that provides bioavailable nitrogen and supports primary production in freshwater lake ecosystems.However,the characteristics of diazotrophic community and nitrogenase activity in freshwater lake sediments remain poorly understood.Here,we investigated the diazotrophic communities and nitrogenase activities in the sediments of three large river-connected freshwater lakes in eastern China using 15N-isotope tracing and nifH sequencing.The sediments in these lakes contained diverse nitrogenase genes that were phylogenetically grouped into Clusters I and III.The diazotrophic communities in the sedimentswere dominated by stochastic processes in Hongze Lake and Taihu Lake,which had heterogeneous habitats and shallower water depths,while in Poyang Lake,which had deeper water and a shorter hydraulic retention time,the assembly of the diazotrophic community in the sediments was dominated by homogeneous selection processes.Temperature and water depth were also found the key environmental factors affecting the sediment diazotrophic communities.Sediment nitrogenase activities varied in the three lakes and within distinct regions of an individual lake,ranging from 0 to 14.58 nmol/(kg·hr).Nitrogenase activity was significantly correlated with ferric iron,total phosphorus,and organic matter contents.Our results suggested that freshwater lake sediment contain high diversity of nitrogen-fixing microorganisms with potential metabolic diversity,and the community assembly patterns and nitrogenase activities varied with the lake habitat.
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State Key Laboratory of Lake and Watershed Science for Water Security,No.2024SKL016National Natural Science Foundation of China,No.42002204,No.42373060+1 种基金Innovative Training Program for University Students,No.2024219,No.2024224Jiangsu Provincial Government Scholarship Program for Studying Abroad,No.2024-075。
文摘Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem has been increasingly degraded,especially with the frequent cyanobacteria blooms,which directly threatens the maintenance of ecosystem service function and sustainable urban development.In this study,several sedimentary cores were collected from Hudie Lake located in the Yangtze River Delta in China that had not been dredged for centuries.Using one of the sediment cores that spans the past 200 years,we reconstructed the long-term environmental changes and examined the driving mechanisms of both human activities and natural factors affecting the lake's dynamics.Our results indicated that,with the growth of the city,organic matter and nutrients in the lake had gradually increased.Notably,the significant increase in phosphorus had been a key factor driving cyanobacteria blooms in Hudie Lake.Since the 1960s,urban development and changes in land use around the lake had severely disturbed its natural habitats,leading to peak nutrient levels during the period from 2000 to 2010.
基金Supported by the National Key Research and Development Program of China(No.2022YFC3204100)the National Natural Science Foundation of China(Nos.42107078,42271120)the Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2022GS03)。
文摘Shallow lakes of the middle-lower reaches of Changjiang(Yangtze)River are a globally unique ecosystem essential for the regional sustainable economic development.These lakes have recently been under pressure from both human activities and climate change,underscoring the need for research on their ecological health and drivers.However,most previous studies focused on large lakes(i.e.,over 500 km^(2))and limited ecological elements,such as nutrient levels.Caizi Lake,a relatively small(approximately 226 km^(2)),a Changjiang River-isolated shallow lake,was chosen as a case of study.We assessed its ecological health and analyzed the driving forces using an integrated dataset from in situ observations,remote sensing,and historical data.Our findings indicate that in 2023,the mean ecological health score,reflecting from all selected elements—algal bloom area,zooplankton,macroinvertebrates,macrophytes coverage,comprehensive trophic level index,and biodiversity—was 50.4 out of the maximum of 100.Notably,the ecological health scores for macrophytes coverage(1.9),macroinvertebrates(17.2),and biodiversity(44.0)were particularly low.In 1960–2007,the ecological health was deteriorated as the macrophytes coverage was dropped from 80%to 50%.The degradation of macroinvertebrate communities and a decrease in biodiversity might be primarily due to the eutrophication-induced abnormal algal proliferation.In 2007–2023,elevated water levels might degrade the macrophytes coverage and other aspects of ecological health.Therefore,we proposed an ecological health restoration plan for Caizi Lake focusing on nutrient reduction and water level regulation on the thresholds of total nitrogen and phosphorus concentrations,an and provided a reference for the protection of Caizi Lake and other cases having similar hydromorphic background.
文摘The study of ecological water demand in rivers has been a research hotspot in recent years.In this paper,selecting the widely used research methods(Tennant method,minimum monthly flow average measurement method,monthly average flow guarantee rate method,monthly minimum flow method,7Q 10 improvement method),the ecological water demand of rivers in the Dongting Lake basin was studied.Combined with the hydrological characteristics of the basin water system,the calculation results by the above five methods were averaged.It was obtained that the ecological water demand of rivers in the basin from April to September and from October to next March was 3.876×10^(9) and 3.425×10^(9) m^(3),respectively.The annual ecological water demand was 7.301×10^(9) m^(3),accounting for about 11.46%of the average annual runoff in the basin.The research results can provide a basis for regional water resource utilization planning and are of great significance for maintaining the health of river ecosystems.
基金funded by the Key Program of National Natural Science Foundation of China (42230708,42361144887)the Tianshan Talent Project of Xinjiang Uygur Autonomous Region,China (2022TSYCLJ0056)。
文摘High-altitude glacier-lake systems in the eastern Pamir Plateau,Tajikistan,are highly sensitive elements of Central Asia’s cryosphere and are vital for sustaining regional water resources.The Yashilkul Lake is located within a tectonic depression dammed by an ancient rockslide,forming a large alpine lake.This lake is currently impacted by intensified warming,glacier retreat,and poorly quantified hydrological shift.The primary objective of this study is to assess multi-decadal changes in the Yashilkul and Bulunkul lakes and their surrounding cryosphere between 1994 and 2024.The changes were analyzed using multitemporal Landsat imagery and unmanned aerial vehicle (UAV) surveys,complemented by in situ meteorological observations from the Bulunkul meteorological station spanning the period from 1990 to 2024.Glacier and lake boundaries were extracted from Landsat data,primarily by applying the normalized difference water index,supplemented by manual delineation.UAV photogrammetry characterized dam morphology and adjacent ponds,and climate trends were evaluated with the modified Mann-Kendall test.A significant warming trend of 0.096℃/a and pronounced interannual precipitation variability have driven persistent glacier retreat and lake surface area fluctuations.The Yashilkul Lake’s surface area decreased from 36.40 (±1.15) km^(2) in 2010 to 31.94 (±0.54) km^(2) in 2020 and partially rebounded to 33.99 (±0.60) km^(2) in 2024,while the Bulunkul Lake’s surface area remained nearly stable owing to limited glacial influence.Additionally,UAV surveys conducted in 2022 and 2024 revealed main features of the Yashilkul Lake:rockslidedammed origin,perched ponds along the dam body,and an artificial canal regulating its outflow.Nearby glaciers,particularly Glacier No.369,exhibited strong frontal retreat and proglacial lake expansion.The proglacial lake expanded nearly fourfold from 0.08 (±0.01)km^(2) in 2000 to 0.33 (±0.02) km^(2) in 2024,raising concerns about potential glacial lake outburst floods that could impact the Yashilkul Lake and compromise the integrity of its natural dam.The findings highlight accelerating hydrological and cryospheric transformations in the Pamir Plateau,emphasizing the need for sustained monitoring of glacier-lake systems owing to their critical implications for water security,ecological stability,and downstream hazard management.
基金supported by Hebei Natural Science Foundation(No.JZX2023018)Hebei Natural Science Foundation(No.C2022201042)the 100 Foreign Experts Plans of Hebei Province(No.606080123001).
文摘Antibiotics are widespread in aquatic environments due to their extensive use in human healthcare and ani-mal husbandry.However,research on the occurrence and bioaccumulation of antibiotics in aquatic organisms within shallow wetland lakes remains limited.This study investigated the occurrence and bioaccumulation of ten commonly used antibiotics in the Baiyang Lake,northern China’s largest shallow wetland lake.The results indicated that sulfonamides and fluoroquinolones were the predominant antibiotics in surface water,whereas fluoroquinolones and macrolides were more prevalent in sediment.Fluoroquinolones demonstrated significant potential for bioaccumulation in targeted aquatic organisms,including both animals and plants(Carassius au-ratus and Phragmites australis).The bioaccumulation of antibiotics in Carassius auratus was correlated with their solubility,whereas in Phragmites australis,this was associated with their octanol-water partition coefficients and molecular weights.Ecological risk assessment indicated that most antibiotics posed minimal to low risk levels.However,four antibiotics were exceptions:clarithromycin(12.5%)and sulfamethoxazole(6.25%)presented a high risk in surface water samples,while norfloxacin(25.0%)and ciprofloxacin(25.0%)posed a high risk in sediment samples.Norfloxacin,ciprofloxacin,and roxithromycin were identified as key indicator antibiotics for enhancing the local monitoring and control of antibiotic contamination based on four criteria:(1)high con-centrations,(2)frequent detection,(3)capacity for bioaccumulation,and(4)ecological risk levels.This study contributes to a deeper understanding of the status of antibiotic contamination,bioaccumulation characteristics,and ecological risk in Baiyang Lake,thereby supporting efforts to monitor and regulate antibiotic pollution.
基金supported by the Shanghai Science and Technology Innovation Action Plan(Grant no.23230712200).
文摘This study investigates the potential formation of subglacial lakes beneath the glaciers of the Franz Josef Land archipelago,Russian Arctic,under current and future climatic conditions.Using a one-dimensional heat and mass transfer model,the research evaluates the influence of geothermal heat flow,ice thickness,and surface temperature on basal melting.The model incorporates enthalpy formulation and boundary conditions derived from field data,including temperature profiles and geothermal measurements.Results indicate that subglacial lakes could form under ice masses exceeding 300 m thickness,driven by geothermal heating,though current basal temperatures remain below the melting point.Simulations under the IPCC SSP1-2.6 scenario suggest a gradual warming trend,highlighting the long-term thermal inertia of Arctic glaciers.The study underscores the need for enhanced observational data to validate models and improve predictions of glacial dynamics in response to climate change.
基金Supported by the National Natural Science Foundation of China(No.43277051)the Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education(No.B230203006).
文摘While oceanic and coastal acidification has gained increased attention,long-term pH trends and their drivers in large freshwater systems remain poorly understood.The Laurentian Great Lakes are the world’s largest freshwater system,and in many ways resemble marine ecosystems.However,unlike the open ocean and coastal waters where pH has declined due to rising atmospheric CO_(2),no significant pH trends have been observed in the Laurentian Great Lakes,despite significant ecosystem changes driven partly by the invasion of dreissenid mussels.This study examined 41 years of field observations from Lake Michigan to investigate the long-term carbonate chemistry dynamics.Observational results revealed substantial declines in both total alkalinity(TA)and dissolved inorganic carbon(DIC)over the four decades.Mussel shell calcification emerged as the primary mechanism behind these declines,accounting for 97%and 47%of the observed changes in TA and DIC,respectively,lowering water column pH by 0.24 units.Elevated carbon accumulation in soft mussel tissues,coupled with long-term changes in the air-water pCO_(2)gradient during summer,significantly contributed to long-term DIC variations,explaining 18%and 28%of the lake-wide DIC loss.These two mechanisms also resulted in an overall pH increase of 0.09 and 0.12 units,largely offsetting the calcification-driven pH decrease.These findings bridge a gap in acidification research for large freshwater systems and provide valuable insights for comprehensive lake-wide management strategies.
基金supported by the National Natural Science Foundation of China(No.42225103).
文摘Lakes are carbon dioxide(CO_(2))and methane(CH_(4))emission hotspots,whose associated flux is spatially vari-able.Many studies have investigated the impact of microorganisms and environmental factors on CO_(2) and CH_(4) emissions between different lakes.However,the carbon emissions and their influencing factors of different areas within a single lake remain poorly understood.Accordingly,this study investigates CO_(2) and CH_(4) emission hetero-geneity in a large floodplain lake system and distribution characteristics of associated functional microorganisms.Findings show that mean CO_(2) and CH_(4) flux values in the sub lake area were 62.03±24.21 mg/(m2·day)and 5.97±3.2μg/(m2·day),which were greater by factors of 1.78 and 2.96 compared to the water channel and the main lake area,respectively.The alpha diversity of methanogens in the sub lake area was lower than that in the main lake and water channel areas.The abundance of methanogens in bottom water layer was higher compared with the middle and surface layers.Conversely,the abundance of methane(CH_(4))-oxidizing bacteria in the surface layer was higher than that in the bottom layer.Additionally,the composition of methanogen and CH_(4)-oxidizing bacterial community,chlorophyll a(Chl-a),pH,total phosphorus(TP)and dissolved organic carbon(DOC)con-tent constituted the dominate driving factors affecting lake C emissions.Results from this study can be used to improve our understanding of lake spatial heterogeneous of CO_(2) and CH_(4) emission and the driving mechanisms within floodplain lakes under the coupling effects of functional C microorganisms and environmental factors.
基金supported by the National Natural Science Foundation of China(No.42001084)the Major Science and Technology Projects of Xinjiang Uygur Autonomous Region(Nos.2022A03009-2,2022A03009)the Third Xinjiang Scientific Expedition Program(No.2022xjkk1303)。
文摘Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(ACA)region.However,debate persists regarding whether dryland lakes in this region exhibited aridification or humidification during the Holocene.Lopnur serves as the terminal lake of Tarim rivers during the Holocene,which offers an ideal natural laboratory to address the questions.In this study,a high-resolution chronological framework was established through precise radiocarbon dating.Multi-proxy analyses,including geochemical composition,grain size distributions,MS,LOI,and C/N ratios were conducted from a lacustrine profile in the core area of“Great ear”in the southern part of Lopnur catchment.These analyses enabled the reconstruction of hydrological dynamics and facilitated the disentanglement of independent signals linked to climate variability,runoff fluctuations,and lake-level changes.The results demonstrate that the MidHolocene(7800–4000 cal yr B.P.)was characterized by cold and humid conditions,resulting in elevated surface runoff and lake level.The Late Holocene(4000–1300 cal yr B.P.)experienced intensified aridification,characterized by reduced runoff and declining lake level.These evidences suggested a climatic regime of a distinctive alternation between“cold-wet”and“warm-dry”climatic regimes during the Mid-to-Late Holocene.Compared with the previous studies from adjacent regions,we speculate that the hydroclimatic evolution of Lopnur catchment possibly influenced by a complex interplay of large spatial scale forcings,including variations in annual insolation,greenhouse gas concentrations,and ice sheets,as well as the localized controls such as topographic features,vegetation cover,and cloud-radiative feedbacks.Our findings enhance the understanding of past climatic complexity and provide valuable insights for future water resource management strategies in drylands.
基金supported by the National Natural Science Foundation of China(Nos.42372355,42530706)。
文摘Nitrate pollution is a severe threat to the fragile ecosystems in karst regions.However,our knowledge of the sources and transformations of nitrate in karst cave groundwater is still limited.This study aimed to investigate the temporal and spatial patterns of nitrate dynamics in the underground water of karst caves located on the south bank of the Qingjiang River in central China,through a comprehensive application of multiple approaches,such as hydrochemistry,nitrogen and oxygen isotope compositions of nitrate,and a Bayesian isotope mixing model(SIMMR).During the sampling period(from December 2018 to December 2019),the nitrate concentration did not show an apparent temporal variation;meanwhile,no water samples in this study had a nitrate concentration higher than the limit for drinking water,but the nitrate concentration in karst underground rivers is significantly higher than that in surface water.The results of the comprehensive analyses revealed that the predominant nitrate sources included nitrification in soil and chemical fertilizer,which had mean percentages of 43%and 32%,respectively.The source contribution varied in the outlet water among different caves.The soil-derived nitrate in the underground water from the Shizi Cave accounted for the highest proportion(49%),while chemical-fertilizer-derived nitrate in the underground water from the Mishui Cave accounted for the highest proportion(36%).The dualisotope signatures of nitrate supported a major influence on nitrogen dynamics in the cave underground from nitrification.These findings suggest that nitrate carried by underground rivers in karst caves should be alerted when making the nitrate balance in rivers flowing through karst areas.
基金supported by Guangdong Basic and Applied Basic Research Foundation(Nos.2023A1515110824 and 2025A1515011839)Shenzhen Science and Technology Program(No.RCBS20231211090638066).
文摘Understanding water chemistry in karst regions is crucial for improving global water resource management and deepening our knowledge of the biogeochemical cycles shaping these sensitive environments.Despite advance-ments in karst hydrology,significant gaps remain in long-term trends,underlying processes,and quantitative effects of environmental changes.This is especially true in areas like the Wujiang River(WJ)in China,where human activities such as reservoir construction and land use/cover changes have accelerated hydrochemical changes.We combined recent and historical monitoring data to provide a detailed analysis of the spatial and temporal characteristics,evolution,and controlling factors of major ions in WJ.These findings are important for local water management and contribute to global efforts to manage similar karst systems facing human-induced pressures.Our research shows clear seasonal differences in solute concentrations,with higher levels during the dry season.WJ’s water is rich in calcium,with Ca-HCO_(3) ion pairs being the most common.Reservoir monitor-ing stations show much higher levels of NO_(3)^(−)and SO_(4)^(2−)compared to river-type stations,likely due to longer hydraulic retention time and increased acid deposition.The study confirms the significant role of pH and water temperature in rock weathering processes.Land use/cover changes were identified as the primary drivers of solute variations(46.37%),followed by lithology(13.92%)and temperature(8.35%).Over the past two decades,in-tense carbonate weathering has been observed,especially during wet seasons.Among karstic provinces,Guizhou Province stands out with the highest ion concentrations,indicative of its extensive karst coverage and heightened weathering processes.
基金supported by the funding from Wuhan Institute of Technology to Dr.Siyue Li(Nos.24QD26 and 21QD02).
文摘Aquatic plants have been widely used for lake ecological restoration.The effect of aquatic plants on lake biogeochemical cycling has been investigated intensively,however,plants’effect on biodegradation of dissolved organic carbon(DOC)is rarely studied.Here we designed an indoor incubation experiment to explore the priming effect(PE)of aquatic plant leaching solution on DOC in shallow lakes,referring to as the input of active dissolved organic matter(DOM)that would arouse changes in the degradation rate of original refractory DOM.Waters from 20 urban lakes of different tropic states were incubated to study their PE on DOC by adding leaching solutions from two submerged freshwater plants,Hydrilla(H)and Vallisneria(V).The study showed a clear influence of aquatic plants on PE with varying directions and intensities.The H incubation group showed a PE range of-6.19%–9.79%,with an average of 2.15%±2.70%,whereas the V incubation group exhibited a PE range of-10.03%to 3.60%,with an average of-0.65%±3.11%.The positive and negative PEs by the two plant species indicate a key role of plants over trophic states on organic carbon dynamics in freshwater lakes.From the perspective of plant leaching input,our results reveal that planting aquatic plants whose leaching solution can reduce PE like V could be used to enhance carbon storage and constrain carbon emission.
基金funded by the National Natural Science Foundation of China(No.42061012)the Open Project of Yunnan Province’s First Class Discipline of Soil and Water Conservation and Desertification Control(SBK20240019)。
文摘Major chemical ionic components in water serve as indicators of natural factors in the areas traversed by water bodies,and are thus widely used to elucidate key hydrogeochemical processes,including rock weathering,aquatic evaporation-crystallization,and the input of precipitation-derived materials into river basins.A total of 208 water samples were collected between August 2021 and August 2022 to investigate the hydrochemical characteristics and their influencing factors of the surface water and the groundwater in the Mingyong River Basin.To systematically analyze the data,we combined hydrogeochemical and statistical methods:descriptive statistics characterized ion concentration and physicochemical parameter distributions;Piper trilinear diagrams classified hydrochemical types;Pearson correlation analysis assessed ion-ion and ionTDS dependencies;Gibbs diagrams and ion ratio analysis identified solute sources;and the absolute principal component score-multiple linear regression(APCS-MLR)model quantified the contribution rates of different influencing factors.The results revealed that the dominant cations in the surface water and groundwater are Ca^(2+)and Mg^(2+),while the dominant anions are HCO_(3)^(-)and SO_(4)^(2-).The groundwater exhibits an extended residence time within rock strata,facilitating prolonged interaction with soluble minerals and intensifying the water-rock reaction process,thereby resulting in higher levels of electrical conductivity(EC),pH,and total dissolved solids(TDS)than those in the surface water.Secondly,the parameters of the surface water and groundwater indicate positive correlation.The weathering of rocks constitutes the primary solute source in the water of the basin.The hydrochemical composition of the basin water is primarily influenced by both carbonate and silicate rocks,with a minor contribution from evaporite rocks.The water bodies in the basin are affected by anthropogenic activities.The surface water is influenced by four sources,namely lixiviation-enrich,human activities,geological environmental,and unknown sources.The groundwater is influenced by five sources,namely lixiviation-enrich,primary geological,human activities,geological environmental,and unknown sources.
基金The Science and Technology Basic Resources Survey Project,No.2021FY101002Wetland Protection and Restoration in China Funded by the Palson Institute and Laoniu Foundation,UNDP-GEF Flyway Project,No.PIMS ID:6110。
文摘Effective conservation relies on robust assessments;however,the lack of waterbird data in the Yellow River Basin(YRB)has led to an underestimation of key habitat significance.This study addressed this gap by evaluating YRB wetland conservation importance using waterbirds as indicators and applying Ramsar,Important Bird Areas(IBA),and East Asian-Australasian Flyway(EAAF)criteria.We integrated coordinated surveys with citizen science data,creating a framework that tackles data deficiencies along the under-monitored Central Asian Flyway(CAF).Our analysis identified 75 priority wetlands,supporting 15 threatened species and 49 exceeding global/flyway 1%thresholds,highlighting the basin's biodiversity.We observed strong seasonal habitat use,with high-altitude wetlands vital for breeding and migration,and the Yellow River Delta providing year-round refuge.This research also provided data to refine Baer's Pochard population estimates.Alarmingly,one-third of the identified priority areas,primarily rivers and lakes,remain unprotected.To address this,we recommend systematic surveys,enhanced protected areas,OECMs,and targeted wetland restoration.This study underscores the YRB's role in regional conservation and provides essential data for adaptive management,particularly emphasizing the CAF's importance.
