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
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
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
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
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
In this study,based on MERRA-2 reanalysis data and a multi-algorithm integrated atmospheric river(AR)iden-tification method,the authors reveal the cross-seasonal regulation mechanism of El Niño-Southern Oscillati...In this study,based on MERRA-2 reanalysis data and a multi-algorithm integrated atmospheric river(AR)iden-tification method,the authors reveal the cross-seasonal regulation mechanism of El Niño-Southern Oscillation(ENSO)on winter-spring AR activities in East Asia.The results show that ENSO asymmetrically modulates AR ac-tivity through teleconnection and hysteresis effects,and has significant enhancement/inhibition effects on ARs in different regions.At the onset of El Niño,enhanced southwesterly flow at the western edge of the western Pacific subtropical high(WPSH)leads to enhanced AR activity in the western Pacific,and anomalous southerly winds in the Indian Ocean promote northward transport of water vapor in the Arabian Sea and Bay of Bengal.With a three-month lag,the weakening and eastward retreat of the WPSH weakens the low-latitude AR activity,but persistent southerly winds in the Bay of Bengal maintain the AR activity over Southwest China.The mid-to high-latitude AR response exhibits delayed dynamics,initially dominated by the synergistic effect of the southward deviation of the upper-air rapids and the low-level convergence(double-rapid-flow effect)and later modulated by the Pacific-North American teleconnection(PNA)-triggered East Asian ridge,which enhances the precipitation efficiency through prolonged frontal activity and enhanced cold-warm airmass convergence.Overall,El Niño promotes the development of low-and midlatitude AR activity in East Asia,while La Niña promotes(maritime continental)AR activity in the tropics.This study establishes the“ENSO teleconnection→circulation adjust-ment→East Asian AR response”chain,revealing a cross-seasonal lagged response mechanisms of East Asian AR activity,and provides a theoretical basis for winter and spring climate prediction and extreme precipitation forecasting.展开更多
We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),org...We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.展开更多
The shallow lake wetlands in the middle and lower Yangtze River floodplain are important wintering and stopover habitats for migratory waterbirds on the East Asia-Australia Flyway.With increasing fishery practices in ...The shallow lake wetlands in the middle and lower Yangtze River floodplain are important wintering and stopover habitats for migratory waterbirds on the East Asia-Australia Flyway.With increasing fishery practices in recent years,however,the wetlands have deteriorated significantly and now threaten wintering waterbirds.To gain insight into the influence of deteriorating wetlands on waterbirds,we conducted a survey of wintering waterbird species,population size,and distribution across 11 belt transects in Caizi Lake and Shengjin Lake,two shallow lakes along the Yangtze River in Anhui Province from November 2007-April 2008 and from November 2008-April 2009,respectively.The impacts of different fishery patterns on the distribution of waterbirds were also analyzed.A total of 43 waterbirds species belong to 7 orders of 12 families were counted during the surveys,of which 38 were found in Caizi Lake with a density of 8.2 ind./hm2,and 42 in Shengjin Lake with a density of 3.5 ind./hm2.Geese（Anser cygnoides）,bean geese（Anser fabalis）,tundra swan（Cygnus columbianus）,and dunlin（Calidris alpina） were the dominant species in the two shallow lakes.Species number and individual assemble reached maximum at the end of December and in early January of the following year,without coincidence of the largest flock for different ecological groups.Based on waterbird diversity across the 11 belt transects and the fishery patterns,habitats could be divided into three groups.Gruiformes,Anseriformes and Charadriiformes had relatively higher densities in the natural fishery zones and lower densities in the cage fishery zones;whereas,the density of Ardeidae showed little change across all lake zones.It is important to develop sustainable fishery patterns in shallow lakes along the middle and lower Yangtze River floodplain to better protect resources of wintering waterbirds.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
The Jiangxi province was divided into seven parts according to the concept of watershed,namely Poyang lake area,Fuhe,Xinjiang,Ganjiang,Xiuhe,Raohe and other river watersheds.The ecological supply and demands status of...The Jiangxi province was divided into seven parts according to the concept of watershed,namely Poyang lake area,Fuhe,Xinjiang,Ganjiang,Xiuhe,Raohe and other river watersheds.The ecological supply and demands status of the former six parts from 2000 to 2006 was computed based on the ecological footprint model and a spatiotemporal comparative analysis to them was conducted.The result showed that:①all the studied areas had an increasing ecological deficit and they were in the status of unsustainable development;② the arable land footprint's demand were about 80% of their total footprint's demand respectively,so it was of great significance to protect and exploit arable land resources scientifically;③ the ecological deficit of grassland and forest resources can not be ignored.展开更多
The construction of Peach Blossom Lake Waterfront Park on the Chan River in Xi'an City gives tourists and Xi'an citizens a waterfront park.By participating the field investigation,feasibility study,demonstrati...The construction of Peach Blossom Lake Waterfront Park on the Chan River in Xi'an City gives tourists and Xi'an citizens a waterfront park.By participating the field investigation,feasibility study,demonstration of design scheme as well as extended preliminary design and construction drawing design of the project,the author studied the "maintenance" and "innovation" in constructing modern urban waterfront parks by combining landscape design knowledge and practices,that is to say,how to inherit Chinese traditional culture and gardening art while making innovations,and achieve the organic integration of traditional cultural elements and modern functional elements.展开更多
Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river （Fuhe River） in North China were analyzed for polybrominated diphenyl ethers （PBDEs） and decabromodiphenylethane （DBDPE）....Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river （Fuhe River） in North China were analyzed for polybrominated diphenyl ethers （PBDEs） and decabromodiphenylethane （DBDPE）. The concentrations of PBDEs and DBDPE in sediments ranged from 5.5 to 300.7 ng/g dry weight （dw） and 1.1 to 68.2 ng/g dw, respectively. Their levels in sediments in Fuhe River were significantly higher than those in Balyandian Lake. Compared to data from other regions, the PBDE levels in surface sediments from Baiyangdian Lake and Fuhe River were in the medium to lower range. Among the PBDE congeners, BDE209 was predominant, with contributions to the total PBDEs ranging from 79.4% to 97.3% in sediment samples. For the lowly brominated congeners （tri- to hepta-BDE）, BDE47 and BDE99 were the most abundant, which contributed 52.1% and 44.1% to the sum of tri- to hepta-BDEs in the sediments from Baiyangdian Lake and Fuhe River, respectively. The compositional patterns of PBDEs in Baiyangdian Lake sediments indicated that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. The present study suggested that the importance of Fuhe River as a possibly potential sources of PBDEs contamination in Baiyangdian Lake.展开更多
Seasonal water-level fluctuations （WLF） play a dominate role in lacustrine ecosys- tems. River-lake interaction is a direct factor in changes of seasonal lake WLF, especially for those lakes naturally connected to u...Seasonal water-level fluctuations （WLF） play a dominate role in lacustrine ecosys- tems. River-lake interaction is a direct factor in changes of seasonal lake WLF, especially for those lakes naturally connected to upstream and downstream rivers. During the past decade, the modification of WLF in the Poyang Lake （the largest freshwater lake in China） has caused intensified flood and irrigation crises, reduced water availability, compromised water quality and extensive degradation of the lake ecosystem. There has been a conjecture as to whether the modification was caused by its interactions with Yangtze River. In this study, we investi- gated the variations of seasonal WLF in China＇s Poyang Lake by comparing the water levels during the four distinct seasons （the dry season, the rising season, the flood season, and the retreating season） before and after 2003 when the Three Gorge Dam operated. The Water Surface Slope （WSS） was used as a representative parameter to measure the changes in river-lake interaction and its impacts on seasonal WLF. The results showed that the magni- tude of seasonal WLF has changed considerably since 2003; the seasonal WLF of the Poy- ang Lake have been significantly altered by the fact that the water levels both rise and retreat earlier in the season and lowered water levels in general. The fluctuations of river-lake in- teractions, in particular the changes during the retreating season, are mainly responsible for these variations in magnitude of seasonal WLF. This study demonstrates that WSS is a rep- resentative parameter to denote river-lake interactions, and the results indicate that more emphasis should be placed on the decrease of the Poyang Lake caused by the lowered water levels of the Yangtze River, especially in the retreating season.展开更多
Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers for...Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C （10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong） and a series of ESR （electron spin resonance） ages at Linzhi town and previous data by other experts, paleolakes persisted for 691±305 kaBP middle Pleistocene ice age, 75-40 kaBP the early stage of last glacier, 27-8 kaBP Last Glacier Maximum （LGM）, existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale： the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn＇t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn＇t form stable lake.展开更多
By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two. water bodie...By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two. water bodies and their response to the operation of the Three Gorges Reservoir （TGR） from different time scales are analyzed based on their hydraulic relations. The results are shown as follows. Firstly, during July-September, the replenishment ability of Three Outlets to Dongting Lake is stronger, and in January-March, the replenishment ability of Dongting Lake to Yangtze River is stronger. Secondly, there has been an obvious inter-decadal wave on the water exchange coefficient between Dongting Lake and Yangtze River. In 1951-1958 and 1959-1968, the replenishment ability of Three Outlets to Dongting Lake was stronger, but in 2003-2010, the replenishment ability of Dongting Lake to Yangtze River has been strengthened. Thirdly, the spill-division ability of Three Outlets weakens, and the water of Dongting Lake coming from Three Outlets decreases either in typical years or under different dispatching modes of the TGR after the operation of the Three Gorges Reservoir. Furthermore, the water of Dongting Lake coming from Four Rivers takes the dominant position, which obviously enhances the replenishment ability of Dongting Lake to Yangtze River. Fourthly, if the effect of the runoff fluctuation in the basin is not considered, the evolution characters of the exchange capacities and the exchange process between Dongting Lake and Yangtze River in different time scales are generally changed with the variation of the water exchange amount between them, although the factors influencing the water exchange capacities between them is very complex. These show that there is an in-line growth or decline relation between the river-lake water exchange ability and the river-lake water exchange amount.展开更多
The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary l...The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting （Lake ED） during a 35-year study period （1980-2014）. Specifically, we investigated Lake ED＇s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge abil- ity under different hydrologic conditions of the Changjiang River. The results show that （1） the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m3/s in Changjiang River＇s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. （2） Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED.展开更多
On the basis of the Taihu water resources assessment, an analysis of the importance and rationality of the water diversion from the Yangtz,e River to Taihu Lake in solving the water problem and establishing a harmonio...On the basis of the Taihu water resources assessment, an analysis of the importance and rationality of the water diversion from the Yangtz,e River to Taihu Lake in solving the water problem and establishing a harmonious eco-environment in the Taihu Basin is performed. The water quantity and water quality conjunctive dispatching ＇decisi＂ofi-makifig support system, which ensures flood control, water supply and eco-aimed dispatching, is built by combining the water diversion with flood control dispatching and strengthening water resources monitoring and forecasting. With the practice and effect assessment, measures such as setting the -integrated basin management format, further developing water diversion and improving the hydraulic engineering projects system and water monitoring system are proposed in order to maintain healthy rivers and guarantee the development of the economy and society in the Taihu Basin.展开更多
The hydrodynamic effects of reconnecting a lake group with the Yangtze River were simulated using a three-dimensional hydrodynamic model. The model was calibrated and validated using the measured water temperature and...The hydrodynamic effects of reconnecting a lake group with the Yangtze River were simulated using a three-dimensional hydrodynamic model. The model was calibrated and validated using the measured water temperature and total phosphorous. The circulation patterns, water temperature, and water exchange conditions between sub-lakes were simulated under two conditions： （1） the present condition, in which the lake group is isolated from the Yangtze River; and （2） the future condition, with a proposed improvement in which connecting the lake group with the Yangtze River will allow river water to be diverted into the lake group. The simulation period selected was characterized by extremely high temperature and very little rain. The results show that the cold inflow from the river has a significant effect on the water temperature only near the inlets, and the effect is more obvious in the lower water layers than that in the upper ones. The circulation pattern changes significantly and small-scale vortices only exist in part of the lake regions. The water exchange between sub-lakes is greatly enhanced with the proposed improvement. The water replacement rate increases with water diversion but varies in different sub-lakes. Finally, a new water diversion scheme was proposed to avoid contamination of some lakes in the early stage.展开更多
The lake-breeze at Taihu Lake generates a different specific heat capacity between the water body and the surrounding land. Taihu Lake has a significant impact on the atmospheric conditions and the air quality in the ...The lake-breeze at Taihu Lake generates a different specific heat capacity between the water body and the surrounding land. Taihu Lake has a significant impact on the atmospheric conditions and the air quality in the Yangtze River Delta. This phenomenon is referred to as the Taihu Lake effect. In this study, two simulations were conducted to determine the impact of the Taihu Lake effect in the reference experiment （R-E） and sensitivity experiments （NO_TH）. The control simulations demonstrated that the meteorological field and the spatial distribution of ozone （03） concentrations over Taihu lake obviously changed once the land-use type of water body was substituted by cropland. The surface temperature of Taihu Lake was reduced under the impact of Taihu Lake, and a huge temperature difference caused a strong lake-breeze effect. The results also showed that the difference in the average concentrations of 03 between the R-E and NO_TH experiments reached 12 ppbv in most areas of Taihu Lake, all day, on 20 May 2014. During daytime （0800-1600 LST, LST=UTC＋8）, the influence of the Taihu Lake effect on 03 in the Suzhou region was not significant. However, the influence of the Taihu Lake effect on 03 in the Suzhou region was obvious during nighttime （1800-2400 LST）. The larger changes in the physical and chemical processes were horizontal and vertical advections under the influence of the Taihu Lake effect in Taihu Lake.展开更多
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 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.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 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.
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[grant number 41830964]the Natural Science Foundation of Hunan Province[grant number 2023JJ40666]。
文摘In this study,based on MERRA-2 reanalysis data and a multi-algorithm integrated atmospheric river(AR)iden-tification method,the authors reveal the cross-seasonal regulation mechanism of El Niño-Southern Oscillation(ENSO)on winter-spring AR activities in East Asia.The results show that ENSO asymmetrically modulates AR ac-tivity through teleconnection and hysteresis effects,and has significant enhancement/inhibition effects on ARs in different regions.At the onset of El Niño,enhanced southwesterly flow at the western edge of the western Pacific subtropical high(WPSH)leads to enhanced AR activity in the western Pacific,and anomalous southerly winds in the Indian Ocean promote northward transport of water vapor in the Arabian Sea and Bay of Bengal.With a three-month lag,the weakening and eastward retreat of the WPSH weakens the low-latitude AR activity,but persistent southerly winds in the Bay of Bengal maintain the AR activity over Southwest China.The mid-to high-latitude AR response exhibits delayed dynamics,initially dominated by the synergistic effect of the southward deviation of the upper-air rapids and the low-level convergence(double-rapid-flow effect)and later modulated by the Pacific-North American teleconnection(PNA)-triggered East Asian ridge,which enhances the precipitation efficiency through prolonged frontal activity and enhanced cold-warm airmass convergence.Overall,El Niño promotes the development of low-and midlatitude AR activity in East Asia,while La Niña promotes(maritime continental)AR activity in the tropics.This study establishes the“ENSO teleconnection→circulation adjust-ment→East Asian AR response”chain,revealing a cross-seasonal lagged response mechanisms of East Asian AR activity,and provides a theoretical basis for winter and spring climate prediction and extreme precipitation forecasting.
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20240036)the National Natural Science Foundation of China(Grant Nos.U24A20515,22276099,and 22361162668)Guangxi Key Research and Development Program,China(Grant No.Guike AB24010074)。
文摘We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.
基金Supported partly by the National Natural Science Foundation of China(30870317)EU-China Biodiversity Programme(00056783)Anhui Academic and Technical Leader Fund
文摘The shallow lake wetlands in the middle and lower Yangtze River floodplain are important wintering and stopover habitats for migratory waterbirds on the East Asia-Australia Flyway.With increasing fishery practices in recent years,however,the wetlands have deteriorated significantly and now threaten wintering waterbirds.To gain insight into the influence of deteriorating wetlands on waterbirds,we conducted a survey of wintering waterbird species,population size,and distribution across 11 belt transects in Caizi Lake and Shengjin Lake,two shallow lakes along the Yangtze River in Anhui Province from November 2007-April 2008 and from November 2008-April 2009,respectively.The impacts of different fishery patterns on the distribution of waterbirds were also analyzed.A total of 43 waterbirds species belong to 7 orders of 12 families were counted during the surveys,of which 38 were found in Caizi Lake with a density of 8.2 ind./hm2,and 42 in Shengjin Lake with a density of 3.5 ind./hm2.Geese（Anser cygnoides）,bean geese（Anser fabalis）,tundra swan（Cygnus columbianus）,and dunlin（Calidris alpina） were the dominant species in the two shallow lakes.Species number and individual assemble reached maximum at the end of December and in early January of the following year,without coincidence of the largest flock for different ecological groups.Based on waterbird diversity across the 11 belt transects and the fishery patterns,habitats could be divided into three groups.Gruiformes,Anseriformes and Charadriiformes had relatively higher densities in the natural fishery zones and lower densities in the cage fishery zones;whereas,the density of Ardeidae showed little change across all lake zones.It is important to develop sustainable fishery patterns in shallow lakes along the middle and lower Yangtze River floodplain to better protect resources of wintering waterbirds.
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 ...
文摘The Jiangxi province was divided into seven parts according to the concept of watershed,namely Poyang lake area,Fuhe,Xinjiang,Ganjiang,Xiuhe,Raohe and other river watersheds.The ecological supply and demands status of the former six parts from 2000 to 2006 was computed based on the ecological footprint model and a spatiotemporal comparative analysis to them was conducted.The result showed that:①all the studied areas had an increasing ecological deficit and they were in the status of unsustainable development;② the arable land footprint's demand were about 80% of their total footprint's demand respectively,so it was of great significance to protect and exploit arable land resources scientifically;③ the ecological deficit of grassland and forest resources can not be ignored.
文摘The construction of Peach Blossom Lake Waterfront Park on the Chan River in Xi'an City gives tourists and Xi'an citizens a waterfront park.By participating the field investigation,feasibility study,demonstration of design scheme as well as extended preliminary design and construction drawing design of the project,the author studied the "maintenance" and "innovation" in constructing modern urban waterfront parks by combining landscape design knowledge and practices,that is to say,how to inherit Chinese traditional culture and gardening art while making innovations,and achieve the organic integration of traditional cultural elements and modern functional elements.
基金supported by the National Basic Research Program(973) of China(No. 2006CB403306)the National Natural Science Foundation of China(No.30870311)
文摘Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river （Fuhe River） in North China were analyzed for polybrominated diphenyl ethers （PBDEs） and decabromodiphenylethane （DBDPE）. The concentrations of PBDEs and DBDPE in sediments ranged from 5.5 to 300.7 ng/g dry weight （dw） and 1.1 to 68.2 ng/g dw, respectively. Their levels in sediments in Fuhe River were significantly higher than those in Balyandian Lake. Compared to data from other regions, the PBDE levels in surface sediments from Baiyangdian Lake and Fuhe River were in the medium to lower range. Among the PBDE congeners, BDE209 was predominant, with contributions to the total PBDEs ranging from 79.4% to 97.3% in sediment samples. For the lowly brominated congeners （tri- to hepta-BDE）, BDE47 and BDE99 were the most abundant, which contributed 52.1% and 44.1% to the sum of tri- to hepta-BDEs in the sediments from Baiyangdian Lake and Fuhe River, respectively. The compositional patterns of PBDEs in Baiyangdian Lake sediments indicated that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. The present study suggested that the importance of Fuhe River as a possibly potential sources of PBDEs contamination in Baiyangdian Lake.
基金National Basic Research Program of China （＂973＂ Program）, No.2012CB417006 National Natural Science Foundation of China, No.41171024 No.41271500
文摘Seasonal water-level fluctuations （WLF） play a dominate role in lacustrine ecosys- tems. River-lake interaction is a direct factor in changes of seasonal lake WLF, especially for those lakes naturally connected to upstream and downstream rivers. During the past decade, the modification of WLF in the Poyang Lake （the largest freshwater lake in China） has caused intensified flood and irrigation crises, reduced water availability, compromised water quality and extensive degradation of the lake ecosystem. There has been a conjecture as to whether the modification was caused by its interactions with Yangtze River. In this study, we investi- gated the variations of seasonal WLF in China＇s Poyang Lake by comparing the water levels during the four distinct seasons （the dry season, the rising season, the flood season, and the retreating season） before and after 2003 when the Three Gorge Dam operated. The Water Surface Slope （WSS） was used as a representative parameter to measure the changes in river-lake interaction and its impacts on seasonal WLF. The results showed that the magni- tude of seasonal WLF has changed considerably since 2003; the seasonal WLF of the Poy- ang Lake have been significantly altered by the fact that the water levels both rise and retreat earlier in the season and lowered water levels in general. The fluctuations of river-lake in- teractions, in particular the changes during the retreating season, are mainly responsible for these variations in magnitude of seasonal WLF. This study demonstrates that WSS is a rep- resentative parameter to denote river-lake interactions, and the results indicate that more emphasis should be placed on the decrease of the Poyang Lake caused by the lowered water levels of the Yangtze River, especially in the retreating season.
基金supported by Project No.1212011120185 sponsored by China Geological Survey
文摘Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C （10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong） and a series of ESR （electron spin resonance） ages at Linzhi town and previous data by other experts, paleolakes persisted for 691±305 kaBP middle Pleistocene ice age, 75-40 kaBP the early stage of last glacier, 27-8 kaBP Last Glacier Maximum （LGM）, existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale： the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn＇t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn＇t form stable lake.
基金National Natural Science Foundation of China, No.41071067 Construct Program of the Key Discipline of the Physical Geography in Hunan Province
文摘By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two. water bodies and their response to the operation of the Three Gorges Reservoir （TGR） from different time scales are analyzed based on their hydraulic relations. The results are shown as follows. Firstly, during July-September, the replenishment ability of Three Outlets to Dongting Lake is stronger, and in January-March, the replenishment ability of Dongting Lake to Yangtze River is stronger. Secondly, there has been an obvious inter-decadal wave on the water exchange coefficient between Dongting Lake and Yangtze River. In 1951-1958 and 1959-1968, the replenishment ability of Three Outlets to Dongting Lake was stronger, but in 2003-2010, the replenishment ability of Dongting Lake to Yangtze River has been strengthened. Thirdly, the spill-division ability of Three Outlets weakens, and the water of Dongting Lake coming from Three Outlets decreases either in typical years or under different dispatching modes of the TGR after the operation of the Three Gorges Reservoir. Furthermore, the water of Dongting Lake coming from Four Rivers takes the dominant position, which obviously enhances the replenishment ability of Dongting Lake to Yangtze River. Fourthly, if the effect of the runoff fluctuation in the basin is not considered, the evolution characters of the exchange capacities and the exchange process between Dongting Lake and Yangtze River in different time scales are generally changed with the variation of the water exchange amount between them, although the factors influencing the water exchange capacities between them is very complex. These show that there is an in-line growth or decline relation between the river-lake water exchange ability and the river-lake water exchange amount.
基金Key Research Program of the Chinese Academy of Sciences,No.KFZD-SW-318National Basic Research Program of China,No.2012CB417006National Natural Science Foundation of China,No.41601041
文摘The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting （Lake ED） during a 35-year study period （1980-2014）. Specifically, we investigated Lake ED＇s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge abil- ity under different hydrologic conditions of the Changjiang River. The results show that （1） the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m3/s in Changjiang River＇s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. （2） Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED.
基金supported by the Innovation Programmes of the Ministry of Water Resources (Grant No. SCXC2002-09)
文摘On the basis of the Taihu water resources assessment, an analysis of the importance and rationality of the water diversion from the Yangtz,e River to Taihu Lake in solving the water problem and establishing a harmonious eco-environment in the Taihu Basin is performed. The water quantity and water quality conjunctive dispatching ＇decisi＂ofi-makifig support system, which ensures flood control, water supply and eco-aimed dispatching, is built by combining the water diversion with flood control dispatching and strengthening water resources monitoring and forecasting. With the practice and effect assessment, measures such as setting the -integrated basin management format, further developing water diversion and improving the hydraulic engineering projects system and water monitoring system are proposed in order to maintain healthy rivers and guarantee the development of the economy and society in the Taihu Basin.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No. 20110142110064)Huazhong University of Science and Technology Indigenous Innovation Foundation(Grant No. 2010ZZ004-06)
文摘The hydrodynamic effects of reconnecting a lake group with the Yangtze River were simulated using a three-dimensional hydrodynamic model. The model was calibrated and validated using the measured water temperature and total phosphorous. The circulation patterns, water temperature, and water exchange conditions between sub-lakes were simulated under two conditions： （1） the present condition, in which the lake group is isolated from the Yangtze River; and （2） the future condition, with a proposed improvement in which connecting the lake group with the Yangtze River will allow river water to be diverted into the lake group. The simulation period selected was characterized by extremely high temperature and very little rain. The results show that the cold inflow from the river has a significant effect on the water temperature only near the inlets, and the effect is more obvious in the lower water layers than that in the upper ones. The circulation pattern changes significantly and small-scale vortices only exist in part of the lake regions. The water exchange between sub-lakes is greatly enhanced with the proposed improvement. The water replacement rate increases with water diversion but varies in different sub-lakes. Finally, a new water diversion scheme was proposed to avoid contamination of some lakes in the early stage.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0602003)the National Natural Science Foundation of China(Grant No.91544229)
文摘The lake-breeze at Taihu Lake generates a different specific heat capacity between the water body and the surrounding land. Taihu Lake has a significant impact on the atmospheric conditions and the air quality in the Yangtze River Delta. This phenomenon is referred to as the Taihu Lake effect. In this study, two simulations were conducted to determine the impact of the Taihu Lake effect in the reference experiment （R-E） and sensitivity experiments （NO_TH）. The control simulations demonstrated that the meteorological field and the spatial distribution of ozone （03） concentrations over Taihu lake obviously changed once the land-use type of water body was substituted by cropland. The surface temperature of Taihu Lake was reduced under the impact of Taihu Lake, and a huge temperature difference caused a strong lake-breeze effect. The results also showed that the difference in the average concentrations of 03 between the R-E and NO_TH experiments reached 12 ppbv in most areas of Taihu Lake, all day, on 20 May 2014. During daytime （0800-1600 LST, LST=UTC＋8）, the influence of the Taihu Lake effect on 03 in the Suzhou region was not significant. However, the influence of the Taihu Lake effect on 03 in the Suzhou region was obvious during nighttime （1800-2400 LST）. The larger changes in the physical and chemical processes were horizontal and vertical advections under the influence of the Taihu Lake effect in Taihu Lake.
