Showing papers in "Journal of Lake Sciences in 2010"

Lake status,major problems and protection strategy in China

Abstract: Large numbers of lakes with different types are distributed through China.The formation and evolution of the lakes are not only influenced by natural factors in the watersheds,but also deeply disturbed by human activities,which led to different regional evolution characteristics and eco-environmental problems.In recent decades,the number,area and distribution of the lakes have undergone significant changes.Moreover,the lakes are facing many problems such as shrinkage,reduction of storage capacity,water quality decline,serious eutrophication,biodiversity decrease,ecological degradation,barrier of river and lake water and ecological contact,over-development around the shore line and the lake area,etc.These problems have triggered a series of ecological and environmental consequences,seriously affecting the daily lives of the residents and sustainable development of the economy.This paper aims to identify the number,area and distribution of the lakes in China with the area larger than 1km2,based on field survey and investigation.Combined with historical data of lake surveys and relative research results,the major ecological and environmental problems and regional characteristics of the lakes in recent decades are systematically analyzed,and the protection strategies for the lakes in China are proposed.

Modern limnological features of Tangra Yumco and Zhari Namco,Tibetan Plateau

Abstract: Investigation and comparative study of modern limnological features of lakes is a basal work of limnological and paleolimnological study,most lakes on Tibetan Plateau are now still lack of basic information. Tangra Yumco and Zhari Namco are two big inland close lakes which located in North-Tibet Plateau. Based on field investigation conducted in September,2009,we present water depth distribution and modern physicochemical features of the two lakes. Bathymetric survey show that most areas of Zhari Namco are relatively flat with the deepest area of 71.55m,and the deepest water depth of Tangra Yumco is 214.48m,thus being the deepest lake on Tibetan Plateau ever known,also the second deepest lake in China. Lake water show clear stratification of both lakes,temperature gradients of thermocline are 1.1℃/m and 0.57℃/m in Zhari Namco and Tangra Yumco,respectively,and the lowest temperature is 1.6℃ which is recorded in hypolimnion in Tangra Yumco. Conductivity in epilimnion of both lakes is 18500μS/cm and 12900μS/cm,respectively. Lake water pH exceeds 10 in epilimnion while decreasing to about 5 in hypolimnion of both lakes,showing different acidic and alkaline characteristics. Both conductivity and dissolved oxygen show synchronous abrupt changes in thermocline,indicating the influence of water temperature on physico-chemical characteristics of lake water.

Fish diversity and fishery resources in lakes of Yunnan Plateau during 2007-2008

Abstract: To study current status of fishery resources and fish diversity in Yunnan Plateau lakes,a survey was carried out in 11 lakes during 2007-2008.Total 39 fish species belonging to 7 orders,13 families and 33 genera were recorded.Cypriniformes were the richest,accounting for 65.0% of total fish species.There were 14 native fishes and 25 exotic fishes being recorded during the survey.In terms of species richness,exotic fishes have dominated in each lake.Fish fauna is characteristic of a shifting from the Plateau to the Plain characters.The age structure analysis showed that year 0+ and 1+ individuals dominated in most economic fishes.Analysis showed that native species diversity was closely correlated with lake elevation and area.The diversity of native species was highest in elevation of 1700-1800m above sea level.There was significant positive relationship between diversity of native species and lake area.Some conservation suggestions were gave at the end of the paper.

Spectral features,remote sensing identification and breaking-out meteorological conditions of algal bloom in Lake Dianchi

Abstract: Based on high spectral reflectivity features of Blue-green Algal Bloom(BAB) in Lake Dianchi,by MODIS satellite remote sensing data,RGB:621 combined false color synthesis and Normalized Difference Vegetation Index(ADVI) method,we found that green region in false color synthesis image and the region with NDVI value-0.1 were just the BAB area.When -0.1≤ADVI≤0.2,slight BAB occurred,and bloom coverage in a pixel reaches 0-30%;when 0.2ADVI≤0.4,moderate bloom happened, bloom coverage in a pixel reached 31%-80%;dense bloom comed forth while ADVI0.4,and bloom coverage in a pixel can be 81%-100%.From June to September is the key period for BAB breaking-out in Lake Dianchi,and the key factors to affect BAB breaking-out maybe sunshine and wind velocity.During this period,if the sunshine can last for only 4～5 hours and the wind velocity≤2m/s,it's quite easy for BAB breaking-out.

Remote sensing analysis for changes of lakes in the southeast of Qiangtang area,Qinghai-Tibet Plateau in recent 30 years

Abstract: This study presented a remote sensing/GIS-based method to monitor changes of lakes in the southeast of Qiangtang area,Qinghai-Tibet Plateau.The Landsat TM/ETM+ and CBERS CCD images together with 1:100000 topographic maps were applied to research 22 lakes from the area.Methods of changing intensity index and quadrant-azimuth analysis were used to mainly research the urban expansion.The lakes area in recent 30 years were analyzed by changing intensity and spatial differential features.The results showed that the lake area had an expanding trend from year 1975 to 2005,and the total area had enlarged about 1162.19km2.Among these lakes,the Selin Co had expanded the largest area with 510.02km2 and significant expanding northwards.Meanwhile,the Lake Guojialun had the highest changing intensity in the area.

Lake changes in spatial evolution and area in source region of Three Rivers in recent 30 years

Abstract: This paper presents the changes of lakes in the source region of Three Rivers (the Yangtze,Yellow and Nujiang Rivers) in recent 30 years by using the methods of GIS and remote sensing.Time slices of 40 images of Landsat MSS/TM/ETM+ and CBERS CCD are divided into four stages of the last 30 years.Each area of the 24 lakes is more than 15km2 and the overall area is more or less 90%of the entire lake area in the Three Rivers.Firstly,the vegetation index method is used to detect the lakes from the images,and manual interpretation is consistent to modify the detection.Then the spatial evolutions of 24 lake variations are built up based on the water body boundaries.Finally,the index of the lake loss intensity is introduced to analyze changes of lake area and the distribution.The result presents that the total area of all 24 lakes declined from the first stage to the third stage (1999-2002),and then increased slightly during the fourth stage.However,the amount of reduced area is more than increases and the total area has lost 65.76 km2 during recent 30 years.The present study provides benefit to understand the regional response to climatic change and utilize the water resources reasonably in the Source Region of Three Rivers.

Effects and significance of organic nitrogen and phosphorous in the lake aquatic environment

Abstract: Domestic and foreign scholars develop a lot of researches on the nutrient substances and their circulation for a long time,such as nitrogen and phosphorus,and make much progresses on its pollution processes,control and management.The researches are focusing on the total nitrogen,total phosphorus and inorganic nitrogen-phosphorus at present,while little research work about the sources and cycle of organic nitrogen-phosphorous,and its ecological effects has been done.Recent study shows that organic nitrogen and phosphorous is an important component in the lake water environment and sediments,and it can transfer into bio-available nutrient by enzymatic hydrolysis and microbial activity.This behavior plays an important role in the lake ecosystem. In this paper,we analyze on the research progresses of organic nitrogen-phosphorous,and discusses on its significance,research difficulties,main technology breaks and the existing scientific issues in the lake water environment study.It is pointed out that the study on organic nitrogen and phosphorous can contribute to the study of aquatic ecosystem and eutrophication mechanism, and it has great value on the research of developing water quality standard,environmental quality assessment,pollution control and ecological restoration.The results show that on the basis of inorganic nitrogen-phosphorous study,the main research trend in this field in the future should focuses on the temporal-spatial distribution characteristics,main interfacial migration and transformation and its bioavailability of the nutrition component,such as organic nitrogen and phosphorous,and also focuses on the revealing the coupling relationship between the organic nitrogen-phosphorous and the life process of lake,and improving the nitrogen-phosphorous theory.

Dynamics of phytoplankton and water quality with control of cyanobacterial bloom in Lake Xuanwu,Nanjing

Abstract: Lake Xuanwu is a typical urban eutrophic lake.Microcystis bloom broke out in a large area of Lake Xuanwu in the summer of 2005.The main method used to control the Microcystis bloom was the application of modified clay.In order to discover the changes of the water ecological situation,the following tests were performed:inquiry into the changes of the quality of water and phytoplankton after the treatment,the analysis to the type and quantity of phytoplankton and physico-chemical indexes.The results show:the amount of phytoplankton reduced,while the species increased after the treatment,the concentration of Chl.a and TP reduced, with a substantial increase in SD,the concentration of TN was undulatory with phytoplankton density and Potamogeton crispus growth.

Monitoring and analysis on "Black Water Aggregation" in Lake Taihu,2009

Abstract: "Black Water Aggregation" (BWA) is one of the most serious environmental hazards occurred in Lake Taihu.Based on the investigation in relevant areas during Apr.-Oct.,2009,the BWA status was analysed.11 BWA were observed in western Lake Taihu,Meiliang Bay and Gonghu Bay.Comparison of blue-green algal blooms,water level,water-quality in recent years gave insight to the further understanding of BWA.The algal bloom was less serious in intensity,frequency and scale in 2009 than in 2007 and 2008,which reduced the possibility of BWA outbreak.In addition,the ecological dredging project undertaken in northern Lake Taihu since 2007 also functioned for the less serious BWA in 2009.Invertigations of water quality revealed that the lake was still under meso-eutrophic as a whole whereas the western Lake Taihu,Meiliang Bay and Lake Zhushan was hyper eutrophic.In order to mitigate and control the BWA,measures such as algae salvage,ecological dredging,source control and interception and water diversion from the Yangtze River to Lake Taihu.More efficient invertigation in relevent BWA-sensitive areas and setup of monitoring-warning system for BWA are favored for early assertainment and instant handling of BWA,which offers technical guarantee for water supply in Lake Taihu.

Current status and development of water quality of lakes in Yunnan-Guizhou Plateau

Abstract: In the present study,the water quality of 13 lakes,which are located in Yunnan-Guizhou Plateau and total areas are more than 10km2,was evaluated according to the data from the investigation in 2008.The variation of trophic state was analyzed by comparing to historical data prior to 1988-1992.Furthermore,principle component analysis (PCA) was also used to evaluate the effect of water quality parameters,in which the comprehensive evaluation scores of the 13 lakes were calculated according to extracted six principle components of the PCA.Changes in water quality of all lakes,except Lake Chenghai,was able to be explained by influences of trophic state,organic pollution and agricultural non-point source pollution under increasing anthropogenic pressure.However,water quality of Lake Chenghai was mainly affected by changes in water salinity.In addition,we also proposed the comments and suggestions about protection and management of these lakes.

Environmental changes recorded by lake sediments from Lake Jili,Xinjiang during the past 2500 years

Abstract: An 80-cm-long sedimentary core from Lake Jili,which lies in westerly area of China,provided detailed information about paleoclimatic and paleoenvironmental changes in the past 2500 years.The temporal sequence of sedimentary core was constructed using the ~(210)Pb,~(137)Cs and AMS ~(14)C dating methods on the bulk organic matter.Based on analyses of grain-size,total organic carbon,total nitrogen and organic carbon isotope,climatic and environmental evolution history in the past 2500 years was reconstructed. The sequence of climatic changes in the region since 2.5ka BP was established.The climatic changes experienced five stages:warm-wet climate during 500BC-50BC;cold-wet climate during 50BC-650AD;warm-dry climate during 650-1350AD warm period(MWP);cold-dry climate period during 1350-1850AD(LIA),and moderate-dry since 1850AD,including climate warming after 1920s,especially since 1970s.The records of climatic and environmental evolution of Lake Jili were in good according with the historical literature records and other geologic records of adjacent areas.

Lake status of water quality and the changes in Inner Mongolia-Xinjiang Plateau

Abstract: Lakes are abundant in the arid/semi-arid region of Inner Mongolia-Xinjiang Plateau,but many of them are salt lakes and saline lakes so that the lake water resources are poor.In recent years,most lakes in the region have quickly becoming salty,area withered and dry,which greatly damaged the ecological environments of the lakes and their catchments.Eleven fresh and slight saline lakes in this region were chosen to investigate.Based on the analysis of the water quality status and their discrepancy,the characteristics and reasons of the water quality variety were explored.Our results showed that Na+ and SO2-4 were the dominant ions within the lake water of Inner Mongolia,while the lake water in Xinjiang were dominant by multiple ions.The ions and total disolved solid concentrations (TDS) of lake water were different with the water exchange variety.TDSs of lakes surround by mountains,including Lake Kanasi,Fukangtianchi and Sailimu Lake,were stable between 1988 and 2008,which reflected the climate change of the region.The TDSs of Lake Caiwopu and Lake Hongjiannao increased quickly while that of Dalinuo increased slowly,which were impacted by anthropic activates including reservoir building and groundwater exploitation.During the past fifty years,fluctuations of the TDS concentrations in Lake Wulungu,Lake Bosten,Lake Jili and Lake Ulansuhai raised and increased recently because of climatic drying and the development of industry and agriculture.

湖泊底泥疏浚环境效应:iv.对沉积物微生物活性与群落功能多样性的影响及其意义

Abstract: A laboratory experiment for studying the effects of sediment dredging on microbial activity and functional diversity of microbial community of sediments was carried out through one year.Using incubation of undredged(control) and dredged cores,we found that dredging the upper 30cm layer of sediment remarkably affected physico-chemical and microbial characteristics of sediments in the study area of Meiliang Bay,Lake Taihu.The microbial activity in dredged sediments was significantly lower(P0.05)than that in undredged sediments.Sediment dredging affected considerably microbial activity in sediments,and the microbial activity in dredged sediments could not recovery in one year experiment.Sediment dredging also affected the functional diversity of microbial community in sediment,the diversity index of microbial community in early dredged sediments was significantly lower (P0.05) than that in undredged sediments.Sediment dredging modified the community composition of sediment microbial ecosystem and resulted in decreasing of diversity of microbial community.Sediment dredging affected microbial activity and functional diversity of microbial community,which consequently affected the cycling of biogenic elements in sediments.

Spring community structure of phytoplankton from Lake Chaohu and its relationship to environmental factors

Abstract: Spring community structure of phytoplankton from rivers and wetlands in Lake Chaohu catchment was investigated by means of field sampling,and it's relationship with environmental factors was analyzed by detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA).The results showed that 73 species (genera) of phytoplankton have been identified in water from Lake Chaohu,which belonged to Bacillariophyta,Chlorophyta,Cyanophyta,Cryptophyta,Chrysophyta,Pyrrophyta,Euglennophyta and Xanthophyta,respectively.In the water of Lake Chaohu,93.5%of the phytoplankton belonged to the phylum Bacillariophyta,Cyanophyta and Chlorophyta,which constructed the dominant population.Notably the number of Anabaenopsis from the phylum Cyanophyta,the most dominant species,is 21.9%of the numbers of the phytoplankton.In some rivers discharged to Lake Chaohu,the dominant species are also of the phylum Bacillariophyta,Cyanophyta and Chlorophyta,which constitute 82.6%of the phytoplankton.The number of Phormidium (the species of the largest population) reaches as high as 38.3%of the number of the phytoplankton,while the number of Aphanizomenon (the species of the second largest population) reaches 32.6%,both of which belong the phylum Cyanophyta.These two species construct the absolute dominant species.A significant discrepancy in spatial distribution of phytoplanton in the lake was observed.Phytoplankton community structure and spatial distribution in the water were remarkably affected by temperature,turbidity and NO-3-N.However,concentrations of Chl.a,NO-3-N and PO3-4-P were the main environmental variables affecting phytoplankton community structure and spatial distributions in water from rivers discharged to the lake.

Analysis on lake changes since ancient and modern ages using remote sensing in Dagze Co,Tibetan Plateau

Abstract: Lakes on the Tibetan Plateau,which are rarely influenced by disturbance of human activities and mainly controlled by glacier melting and evaporation caused by climate change,are a typical study area of global climate and environment change.Remote sensing technology to monitor lake changes across the plateau has important significance to global climate and environment change research.This paper developed an iterative modern lake extraction method on remote sensing images using index calculation and spatial difference comprehensively,to detect lake changes dynamically;and developed a semi-automatic paleo-shoreline extraction method combined with DEM,so as to analyze paleo-lake change.Combining the two methods,we can clearly and completely get the lake changes across the Tibetan Plateau since the ancient and modern ages.Finally,we took Dagze Co as an example to proceed with the methods,and analyzed its shrinkage conditions since the latest 25 years and since the Great Lake Period.

Amount of pollutants discharged into Lake Taihu from Jiangsu Province,1998-2007

Abstract: Lake Taihu has been seriously polluted recently,and the quality of the water environment has been declining year after year.The situation of the water environment in Lake Taihu directly are affecting the region's economic and social development,so the protection of Lake Taihu has been listed as a national key treatment project.Based on the tour hydrometric gauging data and the water quality monitoring results in the main stream channels entering the lake during 1998-2007,this paper analyzed the water amount into the lake,and the water quality in the main stream channels discharged into the lake,and the amount of pollutants discharged into lake,as well as their variation trends,which will provide technical support and decision-making basis to the water environment comprehensive treatment of Lake Taihu basin.

Paleoclimate evolution since 27.7kaBP reflected by grain size variation of a sediment core from Lake Xingkai,northeastern Asia

Abstract: Lake Xingkai,a boundary lake between China and Russia,is the largest freshwater lake in Northeast Asia.The paleoclimate variation since 27.7kaBP was reconstructed based on a 269cm-long sediment core in Lake Xingkai.The chronology was measured by ~(210)Pb and ~(137)Cs activities and AMS ~(14)C dating.Grain size distribution of the lake sediment was inferred to be a proxy for past precipitation,compared to pollen analysis.The high percentage of coarse silt and high Md values reflect a low lake level, and increase in fine silt indicating plentiful precipitation and the high clay content correspond to cold dry climate.The results show that:It was in cold-dry between 27740 and 25540 cal aBP,when lake level was low,as indicated by high Md values and coarse silt contents of the lake sediments.During 25540 and 23650 cal aBP,the sediments was characterized by low clay content,marking a significant increase in effective precipitation in cold wet climate.The Last Glacial Maximum between 23650 and 19940 cal aBP was marked by high content of clay because of the frozen lake surface,corresponding to especially cold-dry.From 19940 to 14510 cal aBP,precipitation increased when fine silt content increased.The fluctuating characteristics of the sediments grain size indicated that precipitation increased first and decreased finally during 14510 and 10800 cal aBP,corresponding to B(o|¨)lling/Older Dryas/Aller(o|¨)d/Younger Dryas periods.From 10800 to 1050 cal aBP,lake level rose evidently suggested by higher content of fine silt when the precipitation was relatively abundant in Holocene,in which 90-78m section shows that the sand and coarse silt content increased sharply,indicating that the lake level experienced a rapidly decline because of cold-dry climate around the 8.2 kaBP.Since 1105 cal aBP,the portion of sand and coarse silt increased markedly,reflecting low lake level under a cool-dry climate, companied with remarkable increase in soil erosion and terrestrial material into lake possibly related with local human activities.

Variability of stable nitrogen isotopic baselines and its consequence for trophic modeling

Abstract: Ecologists frequently use stable isotopes to measure the pattern and process of interested ecosystems.Comparisons of food web structure among and within ecosystems rely on a baseline isotopic signature for each system.The goal of a trophic baseline is to reflect the isotopic signature of the primary source of materials and nutrients for the food web.In general isotope baseline selection depends on the specific research question and must be tailored to a particular study system.We reviewed the use of the stable nitrogen isotopic signatures of primary producers and primary consumers to develop the baseline in aquatic ecology.Each of these studies used a slightly different method of baseline correction that was tailored to address a question of specific ecological interest. However,choosing an appropriate baseline depends on the inter-and intraspecific spatial,temporal variability of isotopic baselines and on the spatial and temporal context of the ecological question under consideration.We also evaluated to what extent isotopic heterogeneity actually influence consumer's trophic positions at the temporal and intraspecifical scales.The result of trophic position output estimated using an isotopic mixing model was generally variable,provided that baseline variability for trophic position estimation were sufficiently distinct in dietary mixing models.

Retrieval of chlorophyll-a concentration by Three-band model in Lake Chaohu

Abstract: Three-band model is a semi-analytical model based on some assumptions of bio-optical model properties,which is an excellent model for chlorophyll-a. The goal of this study is to analyze the feature of the reflectance spectrum by the data collected on the surface of the Lake Chaohu and to synchronized images of the satellite HJ-1. The different location of feature bands turns out that two models have several differences in the retrieval resolutions. Three bands of two models are 669nm/699nm/735nm and B73(680.49-685.08nm)/B74(685.08-689.74nm)/B81(719.04-724.17nm)respectively. Only when taking the full considerations of the feature of remote sensing data and analyzing both remote sensing theory and image,we can optimize choices of the three bands and archive the target of quantitative retrieving the chlorophyll-a by remote sensing image.

The influence of Tubificid worms bioturbation on the exchange of phosphorus across sediment-water interface in lakes

Abstract: To examine the effects of bioturbation of Tubificid worms on phosphorus exchange across sediment-water interface in lakes,the laboratory incubation experiments were carried out with sediments and lake water from Meiliang Bay and the estuary of Dapu River in Lake TaihuRhizon samplers were used to acquire pore waterTubificid worms increased sediment water content and redox potential in surface sediment,and decreased Fe2+ in pore waterFor sediment from Meiliang Bay,the Tubificid worms did not altered significantly SRP in pore water,while accelerated SRP release from sediment to overlying waterBut for sediment from the estuary of Dapu River,Tubificid worms decreased SRP in pore water and inhibited SRP release from sediment to overlying waterIt suggested that ferrous iron may play an important role in explaining different results

Isolation of antialgal compounds from Potamogeton malaianus and algal inhibitory effects of common fatty acids

Abstract: One active fraction,which mainly contained many kinds of fatty acids,was extracted and isolated from the submerged macrophyte Potamogeton malaianus,then was analyzed by the GC-MS.The EC50,3d fraction on Selenastrum capricornutum was 7.90mg/L.The inhibition of eight fatty acids in the fraction and oleic acid on S.capricornutum confirmed that fatty acids had the allelopathic inhibitory effect and the effect was relevant to the carbon chain and unsaturated linkages,which meant the shorter the carbon chain of the fatty acid,the stronger the algal growth was inhibited,and the more unsaturated linkages in the fatty acid,the stronger the algal growth was inhibited.The combined activity of multi-fatty acids showed synergistic growth inhibition on S.capricornutum.Another fraction,which mainly consisted of sterols,was isolated from the extraction of P.malaianus,but it did not inhibit the growth of S.capricornutum and had no evident influence on the allelopathic inhibition of fatty acids on S.capricornutum.

Structure of phytoplankton community and its relationship with environment factors in Lake Honghu

Abstract: Sampling was carried out in March and July 2008 in order to study the structure of phytoplankton community and its relationship with environment factors in different seasons in Lake Honghu.Total 6 phylum,46 genera and 95 species of phytoplankton were identified.The phytoplankton abundance ranged from 2.00×10~5 to 284×10~5 cells/L.Bacillariophyta was the most abundance phylum,following as Chlorophyta and Cyanophyta.Fragilaria,Scenedesmus and Melosira were the dominant genera,of Algae community structure was different between dry seasons and wet seasons.Due to adaptability of low water temperature and light intensity in dry seasons,diatoms were predominant phylum.Diatoms were also predominant phylum in wet seasons due to abundant Si in water.Principal Components Analysis(PCA) indicated that the kinds of ions and pollutants in the water body were the most important environment factors in the lake.Canonical Correspondence Analysis(CCA) illuminated water temperature,dissolve oxygen and suspended solids could be the main forces structuring the phytoplankton community in the Lake Honghu.

Spatial distribution of lakes hydro-chemical types in Badain Jaran Desert

Abstract: In September,2009,51 samples of lakes as well as 8 of springs and 12 of wells were studies from Lake Guaizi Geological Park in Badain Jaran Desert.The result demonstrated that almost all lakes from southeast edge to hinterland area showed Sulfate-Carbonate-Chloride type.The southeast edge has the most complex type,mainly contained Na+,Cl-,SO42-.It formed into three sub-types for different contents of Ca2+and Mg2+,which attributed to different total dissolved solids.One of the sub-type,had high TDS and without Ca2+,Mg2+ also appeared in north,which seemed to be one type just non-sequential distribution,however,they had huge differences.After a comprehensive analysis,it showed that spatial variation of desert lakes mainly formed by climate,and partly by local precipitation directly or indirectly,and groundwater recharge may be other factor.Compared characteristics of water chemistry among the different part of south and north lake,it showed that the supply source of the hinterland was more unstable than that of southeast,which might be drived by climate drying and warming.

Point source pollution control and problem in Lake Dianchi basin

Abstract: Lake Dianchi is a famous plateau freshwater lake in China,and has been included in the national "The Three Rivers and Three Lakes" treatment project since "the 9th Five-Year Plan".In this study,the point source pollution of 2007 and change tendency in the last 20 years in the Lake Dianchi basin were studied on the analysis of the point source pollution problem.The results indicated that COD,total nitrogen,and total phosphorus discharged of point source from the whole basin in 2007 were 55913t,11222t and 1008t,respectively.COD,total nitrogen,and total phosphorus from domestic sewage contributed 89%,96% and 98% to each total pollution load,respectively.From 1988 to 2007,the point source pollution load yielded in Lake Dianchi basin sustained an increasing trend.However,the final pollution load discharged into the lake decreased,especially the COD and total phosphorus,for the drastic enhancement of ability of sewage treatment.Point source pollution in Lake Dianchi basin can be attributed to four problems:first,city expansion and population growth will put great pressure on the water environment of Lake Dianchi basin;second,the combined drainage system of the old city region,misconnection of rain sewers and sewage sewers of the new city region,and the pumping of river water to treat of sewage treatment plants result in the pollution of combined waste water overflowing which existed for a long time;third,the sewage treatment ability does not match the yield of sewage in some areas,especially during the rainy season,the inability of sewage treatment was an outstanding problem;fourth,terminal treatment of point source pollution no longer meet the need of the protection of Lake Dianchi,and pollution control in the whole process should be addressed.

Advances in the theories and calculation methods of ecological water requirement

Abstract: Ecological water requirement(EWR)is one of the global foci-research subjects in environmental related field,which has an inter-relationship with ecology,hydrology,environmental science,etc.This paper reviews the research advances in EWR at home and abroad,introducing the concepts,classifications and characteristics of EWR and summarizing calculating methods for EWR:inside river course(including rivers,estuaries and lakes) and outside river course(including vegetation,animals,wetlands,cities and covering over-exploitation of ground water).Especially the basic ideas,advantages,disadvantages and conditions in terms of practical application EWR calculation of river ecosystem are pointed out.Meanwhile,the reasons of differences between domestic and foreign research methods are discussed.Foregoing analyses evoke some questions about the current study of EWR in China:1) a consistent and sound understanding of the concept,connotation and extension of EWR has not been obtained so far;2) great attentions should be paid to the applicability of the foreign calculation methods in China;and 3) further progress about the development and application of EWR will be promising due to:combining domestic with foreign calculation methods and reasonable improvement,strengthening the application of new technologies such as 3S,enhancing the research of EWR in humid areas,where water quality-induced water shortage such as South China Pearl River Basin.

Sediment-water nutrient fluxes and the effects of oxygen in Lake Dianchi and Lake Fuxian,Yunnan Province

Abstract: Continuous porewater extraction method was used to study the sediment-water nutrient fluxes and oxygen effects on the benthic nutrient fluxes in Lake Dianchi and Lake Fuxian.Overlying water pH of oxic sediment cores were significantly larger than those of corresponding anoxic ones,while there were no significant differences of porewater pH between the two conditions.It is most likely that the former was dominated by oxic mineralization and less acidic products were produced,while porewater was under anoxic condition and the anoxic mineralization was dominated under both conditions.Porewater species concentration (PO3-4 and NH+4) under the anoxic conditions was significantly lager than the oxic ones,which indicated an increasing of mineralization of organic matter under the former condition.It should be noted that the PO3-4 concentration in porewater was also related to FeOOH-P model.Both phosphorus and ammonium fluxes calculated from the Fick’s first law were all larger than the measured fluxes,which indicated that both nutrients had a potential to be released into the overlying water.However,it was interesting to find that the difference between the diffusive flux and measured flux under the oxic condition were greater than those under the anoxic condition.This implied that both fluxes were affected by oxygen,and the benthic nutrient fluxes could be better described by diffusive model under the anoxic condition than the oxic condition.

Caryotype of Ottelia acuminata var. lunanensis H. Li and evolution of Ottelia Pers

Abstract: Ottelia is a kind of submerged monocots inhabiting only in fresh water.This genus has an important ecological value and much significance of environment-monitoring,as well as the material of a plant systematic study.The auhtors presented for the first time that Ottelia acuminata var.lunanensis H.Li,a peculiar plant growing in the lakes of Stone Forest County of Yunnan Province,China,has 22 somatic chromosomes,which are classified as "1B" caryotype (2n=2x=22=18m+4sm).By analyzing both the flower characteristics and the caryotypes of Ottelia,the consanguineous relationships among its varieties and their evolution were also discussed,which proposed a cell-biological theory for the using and protection of Ottelia.

Trend of streamflow in Lake Qinghai basin during the past 50 years(1956-2007)——Take Buha River and Shaliu River for examples

Abstract: Annual streamflow of Buha River and Shaliu River were studied in this paper.No significant changes were found during the past 50 years,which indicated that the decline of the water level of Lake Qinghai was not affected by the streamflow of the two rivers in Lake Qinghai basin.The monthly mean streamflow of Buha River had declined trend in January,February and March,and the monthly mean streamflow of Shaliu River also had declined trend in January,February,April and May.The yearly streamflow of Buha River was larger than Shaliu River,but the streamflow of Shaliu River was larger than Buha River within the range of from 55%-91%.The monthly steamflow of Buha River and Shaliu River were of great difference.High flow period of Buha River were found in the 1960s,normal flow period in the 1970s and 1980s,while low flow period in the 1990s.Compared with Buha River,the streamflow of Shaliu River was steady.

Experimental study on the effect of sediment resuspension on zooplankton community

Abstract: Sediment resuspension is one of the important characteristics of hydrodynamic processes in shallow lakes.This experimental study was compared with the changes of zooplankton community in different levels of the resuspension to investigate the effect of sediment resuspension on zooplankton.The result shows significantly difference when using different treatments of concentrations of TSS and Chl.a. The cladoceran Bosmina coregoni,Ceriodaphnia cornuta and Rotifers are dominant in resuspended groups,but Daphnia sp.is dominant in no resuspended group.Resuspension produced an effect of deducing size of the composition of zooplankton communities.The abundances of Daphnia carinata,Bosmina coregoni and Rotifers are significant different in different resuspended levels,but Ceriodaphnia cornuta and Calanoidas show no significant different.The concentration of TSS is significant positive correlation with abundances of Rotifers and Bosmina coregoni,but significant and negative correlation with Daphnia sp.abundance,while there is none correlation with other populations.The research shows that the sediment resuspention is one of the important processes determining zooplankton community structure.

The accumulation and potential ecological risk evaluation of heavy metals in the sediment of different lakes within the middle and lower reaches of Yangtze River

Abstract: The concentrations of Co,Cr,Cu,Ni,Pb and Zn in the sediments of Lake Taibai,Lake Longgan,Lake Chaohu and Lake Xijiu in the middle and lower reaches of Yangtze River,were determined.Combined with geochronology,enrichment factors and Hakanson Potential Ecological Risk Index were used to evaluate the accumulation degree and the potential ecological risk of heavy metals in the sediment.The results showed that the status of heavy metal enrichment in the sediment of Lake Taibai and Lake Longgan was in the lower level,while that of Co,Cr,Ni in the Lake Chaohu sediment was low,and Cu,Pb,Zn enrichment reached moderate level.In the sediment of Lake Xijiu,the status of heavy metal enrichment was different from heavy metals,which Co enrichment was very low,Cr and Ni enrichment was in the lower level,and Pb enrichment arrived at the moderate level,and Cu,Zn enrichment reached the higher level.The status of heavy metal contamination in the four lake sediments was ranked as Lake ChaohuLake XijiuLake LongganLake Taibai.The potential ecological risk index of single element was very low,however,based on the potential ecological risk index of multi-elements,there was obvious difference among these four lakes:Lake ChaohuLake XijiuLake LongganLake Taibai.Generally,the enrichment and potential ecological risk in the sediments of Lake Taibai and Lake Chaohu had been increasing since 1965,while those conditions in Lake Longgan and Lake Xijiu tended to decrease in the surface sediment,all of which strongly correlated with the way and intensity of human activities in the catchment areas.In the catchments of Lake Chaohu and Lake Xijiu,the development of industrialization and economy was rapid,and lots of heavy metals were discharged into lakes by human activities,which made these lakes polluted.However,the way of human activities in Lake Longgan and Lake Xijiu catchments was mainly about agriculture,which contributed to a small portion of heavy metals into the sediment.