Abstract:This paper reviews the study progress of lake optics including the theory framework,study methods,bio-optical proper-ties,chromophoric dissolved organic matter (CDOM) biogeochemical cycle,relationships between light and phytoplankton, optical effect of sediment resuspension,lake water color remote sensing.The theory framework of lake optics includes absorption,scatter-ing and attenuation of four optically active substances (pure water,CDOM,phytoplankton and tripton) and the water radiation transfer equation.A series of methods including the field investigation of spatial-temporal pattern of lake optics,the successive ob-servation of hydrodynamic and algal bloom processes, high frequent observation of bio-optical parameters, the experiment controlled and simulated are presented.The spatial-temporal patters of particles absorption, scattering, backscattering, diffuse attenuation co-efficients and euphotic depth in different lakes are obtained,and the interrelationship of particles absorption,scattering,backscat-tering,diffuse attenuation coefficients,euphotic depth and the concentrations of optically active substances are presented.CDOM spectral absorption coefficient,excitation-emission matrix fluorescence spectroscopy are used to characterize the spatial-temporal distribution,source,composition,removal and the contribution of CDOM to ultraviolet radiation attenuation.There is also consid-erable evidence that ultraviolet B radiation has an effect on phytoplankton growth and community structure.A vertically generalized production model of primary production is widely used to estimate phytoplankton primary production.Sediment resuspension has a significant effect on underwater light climate,which decreases transparency and euphotic depth,and further decreases phytoplankton primary production.Many algorithms are presented to estimate several water quality parameters including total suspended matter,chlorophyll-a concentrations and CDOM, phytoplankton absorption coefficients.These results are applied to satellite images for the monitoring of algal bloom in eutrophic lakes.Finally,the future developments of lake optics from the macro and microscopic perspectives have been expected.

Abstract:This paper studied the dynamic variation of zooplankton population during the process of in-situ restoration of a heavily polluted tidal river in southern China by the technology of enhanced ecological floating bed (EEFB) and explored the changing characteristics of zooplankton community structure responding to the river water quality improvement.The results showed that the river water quality was improved after treated by EEFB,and the species of zooplankton increased from 5 to 49 and there occurred co-existence of multiple species instead of single pollution resistant species after implementing the restoration engineering.There was also a significant rise (P<0.01) of monthly zooplankton richness,namely,increasing from the lowest 1.22 ind./L to the highest 47.19 ind./L after the restoration work in the demonstration area comparing to the control area.The diversity index also achieved notable increase,of which Shannon-Wiener diversity index(H') and Margalef species richness index(D)increased from the original 1.27 and 2.22 to 1.62 and 3.12,respectively.In the demonstration area zooplankton diversity showed higher recovery ability than that in the control area which indicated that the employment of in-situ restoration technology of EEPB was effective in raising the ecological recovery efficiency of polluted water bodies.

Abstract:To study the molecular diversity of Microcystis in Fenhe River of Taiyuan,phylogenetic analyses based on ITS、 PC-IGS and gyrB genes were performed from 7 isolated strains of Microcystis.These seven Microcystis strains formed distinct lineages,sug-gesting high diversity of Microcystis.ELISA and whole-cell PCR targeting microcystin synthetase gene (mcyA) were used to deter-mine microcystin production.Results showed that six of the seven strains contain mcyA gene and the microcystin concentrations of the six Microcystis strains ranged from 0.003mg/g to 0.043mg/g.This is the first report of toxic Microcystis in Fenhe River,and it is urgent that more critical measures should be taken for the protection of Fenhe River.

Abstract:In this paper,the high performance liquid chromatography(HPLC) was used to monitor the spatial and temporal distri-bution of dissolved Microcystin-LR and Microcystin-RR in Lake Taihu,and its relationship with physiochemical factors of the lake were also discussed.The results showed that the concentrations of microcystin(MCs) were not different between surface and bottom water in a day,and the highest concentration of microcystins occurred in winter.Concentrations of the MCs changed much during one year in the sampling sites N5 and N1 which located in Zhushan Bay and the western part of Lake Taihu,respectively.General-ly, the concentration of the MC-LR was higher than MC-RR for the year in average while the opposite results appeared in individual month of August and September.Correlation analysis showed that MC-LR was significantly positive correlated with TN,but did not show correlation with TP.During the period of water bloom of cyanobacteria,levels of the MC-LR were significantly positive corre-lated with TP,TN,UV₂₅₄ ,SS,total organic carbon and biomass of cyanobacteria,whereas MC-RR was not significant correlated with all the environmental factors in the statistical test.

Abstract:In water pollution control planning based on total waste load,it is usually necessary to check the total maximum allowa-ble load and choose proper countermeasures to finish the load cut task under specified water quality objectives.With the route anal-ysis method,the continuous control variables in the direct algorithm are discretized,so not only the optimization problem is simpli-fied,but also the result is more practicable and pertinent.Take the Lake Dianchi Catchment as an example,the 6 water pollution control measures were discretized by parameters and the most suitable pollution control schemes were selected under different water quality scenarios with route analysis method.Afterwards,based on the historical and present treatment situation in the study area, the medium-scenario and corresponding countermeasures were suggested for the 12^th Five-Year Water Pollution Control Planning in the Dianchi Cactchment.

Abstract:A cyanobacterial bloom(dominated by Anabaena mucosa) in Gaozhou Reservoir was firstly reported from January to April in 2009, occurred again in 2010.Its maximum cell density reached 3.4×10⁷ cells/L.To understand the characteristics of the cya-nobacterial blooms,the community structure and dynamics of cyanobacteria were investigated monthly from August 2009 to July 2010.There was a significant difference in species composition of cyanobacteria between dry season and flood season in the reser-voir.Cell density in dry season was higher than that in flood season when Anabaena mucosa formed cyanobacterial bloom.This phe-nomenon may attribute to the beneficial conditions to algal growth and accumulation,e.g.low precipitation,low water level and low storage capacity,but hydraulic retention time prolonged and thermal stability increased.Moreover,the decreased water trans-parency and lowering temperature would contribute to Anabaena mucosa turning into the dominant species and to form cyanobacterial blooms.Strong negative correlation between water temperature and cyanobacterial biomass suggested that Anabaena mucosa was a-daptable to low water temperature.In the flood season,increasing of precipitation resulted in high water level,and thermal stratifi-cation occurred in vertical column of the water.Microcystis flos-aquae was dominated in the algal community gradually instead of An-abaena mucosa because of the water stratification,but the bloom disappeared with a dramatic decrease of total cyanobacteral bio-mass.In conclusion,the cyanobacterial bloom in Gaozhou Reservoir was closely related to water temperature and precipitation.

Abstract:Gaozhou Reservoir is an important drinking water source of Maoming city of Guangdong province.Cyanobacteria blooms, occurring in spring of 2009 and 2010,had brought safe hidden trouble to residents.Based on the data collected from the reservoir in two springs,the highest densities of phytoplankton in the spring of 2009 and 2010 were 4.08×10⁷ cells/L and 1.47×10⁸ cells/L,and cyanobacteria densities accounted for 98.2% and 98.7% of total phytoplankton,respectively.The dominant species were Anabaena spp.and Microcystis aeruginosa in the two springs in the reservoir.The TN/TP ratios ranged from 28 to 64,phosphorus was the limiting factor for phytoplankton development.The chlorophyll-a concentration ranged from 2.5 to 31.6 mg/m³ , and the cor-relation between pH(r=0.753, P<0.01)and DO(r=0.565, P<0.05) was excellent.It can be inferred that the main reasons of spring phytoplankton blooms were the high stability of water, water temperature rising and the nitrogen and phosphorus level close to the threshold value of spring phytoplankton blooms.

Abstract:To investigate the effects of sediment types on growth and photosynthetic characteristics in emergent plants,the leaf pig-ment contents,chlorophyll fluorescence and gas exchange of three dominant species(Phragmites communis,Typha minina and Acorus calamus) from aquatic vegetation of Lake Chaohu,which were grown in five different sediment types,were examined.The results showed that in the three emergent plant species, the shoot biomass was highest in T.minina, followed by P.communis, and the lowest in A.calamus.The chlorophyll-a content(Chl.a),chlorophyll-b content(Chl.b),carotenoid content(Car),stomatal conductance,intercellular CO₂ concentration,transpiration rate in T.minina were significantly higher than that in A.calamus and in P.communis,net photosynthetic rate,Fv/Fm and ΦPS Ⅱ in T.minina were significantly higher than that in A.calamus.Ac-cording to correlation analysis,the shoot biomass was positively correlated to net photosynthetic rate,while net photosynthetic rate was significantly correlated to stomatal conductance and intercellular CO₂ concentration.Therefore,the results indicated that the high stomatal conductance,pigment content,as well as Fv/Fm and ΦPS Ⅱ in T.minina plants might lead to the high shoot bio-mass and net photosynthetic rate.Compared to the control(the original sediment),using the four sediment treatments(loosen sedi-ments,organic sediments coverage,soil sediments coverage and sand sediments coverage) in varying degrees have increased pig-ment contents(Chl.a,Chl.b,Car and Chl.a/Chl.b),improved the activity of reaction center(Fv/Fm and ΦPS Ⅱ),and en-hanced stomatal conductance and intercellular CO₂ concentration.As a result,the sediments enhanced photosynthetic rate and plant growth,and the loosen sediments and organic sediments coverage had high effects among the four treatments.

Abstract:Based on chironomid analysis for sediment core T0905 from Meiliang Bay,Lake Taihu,response patterns of chironomid assemblages to lake trophic changes were discussed.Results show that chironomid assemblages experienced a notable community shift from predominant Tanytarsus to Chironomus plumosus-type and Microchironomus dominated at around 1970.Before 1970,chi-ronomid assemblages were dominated by Tanytarsus,which is an indicator of relatively good water quality and moderate trophic sta-tus.Subsequently,the relative abundance of Tanytarsus decreased along with the increase of eutrophic indicators such as Chironomus plumosus-type and Propsilocerus akamusi-type.Especially from 1990,the abundance of Microchironomus tabarui-type had a sharp increase,denoting that Meiliang Bay has already become eutrophic level from meso-eutrophication.

Abstract:In order to comprehend the terrestrialization situation and its driving factors in Lake Nansi, the whole Lake Nansi and 21 inlets of the rivers entering the lake were sampled and investigated in August 2008,June 2009,August 2009,June 2010 and August 2010.The results showed that only 4 sites located in the Natural Reserve of Weishan Island and the inlet of Jiehe River with dense shipping belonged to no terrestrialization,2 sites lying the inlet of Laowanfu River with busy transport and the open water region of Nanyang Lake to slight terrestrialization,other 6 sites were moderate terrestrialization, 12 sites severe terrestrialization and 1 site heavy severe terrestrialization among the 25 sampling sites.The degree of terrestrialization was significantly positively correla-ted to vegetation types,depth and organic matter content of silt,negatively correlated to pH and dissolved oxygen;the abundance of vegetation was close negatively correlated to depth of water,pH and dissolved oxygen;the silting level was positively to total ni-trogen,total phosphorus, organic matter of sediment,negatively to chemical oxygen demand.So apparently the import of exogenous contamination and increase of trophic level promoted the terrestrialization speed,and the unreasonable development in the whole drainage area further accelerated this progress.

Abstract:Concentration and distribution of 19 organochlorines and 6 heavy metals in the surface sediment of southern Lake Taihu were studied and the relevant risk assessment was carried out.The results showed the concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) detected ranged from 0.51-4.98ng/g(dw) and 1.49-15.15ng/g(dw),respec-tively,which was at a low contamination level compared to other fresh water sediments in China.The congener of α-hexachlorocy-clohexane (α-HCH) was the dominant pollutant among OCPs and CB194,and CB28 were the dominant PCBs.The concentration rangesof Cu,Zn,Cr,Ni,Pb and Cd in the surface sediments of southern Lake Taihu were 14.4-79.7mg/kg,69.3-214mg/kg,65.0-99.5mg/kg,24.8-48.7mg/kg,12.3-39.2mg/kg and 0.015-0.563mg/kg,respectively.Effects range low (ERL) and effects range median (ERM) were used to evaluate the ecological risk of organochlorines.It was found that 90% of the sampling sites had a dichlorodiphenyltrichloroethanes (DDTs) value lower than the ERL,and the γ-HCH and PCBs values of all sites were lower than the ERL.The risk assessment was completed on heavy metals in sediments by using the potential ecological risk index (RI).The results indicated that the overall ecological risk caused by heavy metals was low.The potential ecological risk index of Cd was relatively higher,and the RIs of several heavy metals in XMK-0 were relatively higher than that in other sites.Al-though the concentration levels of the above organochlroine and heavy metal pollutants in the surface sediments of southern Lake Taihu were low and no serious threat has been observed to the ecological system,the prevention to these contaminations should not be ignored for their accumulative effect and toxicity in the environment.

Abstract:The temporal and spatial distribution patterns of chlorophyll-a and its correlation with the main environmental factors were analyzed according to the monthly investigation from January, 2007 to December, 2009 in Lake Qiandao where a large number of silver carp and bighead carp stocked.Results showed that the concentration of chlorophyll-a in sampling stations located in the upper reach riverine and transitional zones of the reservoir showed a significant seasonal variations with two concentration peaks oc-curred in spring and late summer or early fall,respectively.The concentrations of chlorophyll-a in upstream sites(in the riverine and transitional zones) were significantly higher than those of downstream sites.The chlorophyll-a during the warm season was usu-ally stratified with a concentration peak occurring at depths between 4m and 12m, occasionally at a depth of 20m.The result of cor-relation analysis showed a weak correlation between chlorophyll-a and NO₂-N,COD_Mn ,water temperature( WT) and silicate (SiO₃^2- ),while no significant correlations of the chlorophyll-a were found with other environmental factors,especially with the TP in the water.The regression equation between chlorophyll-a and the correlated environmental factors could be expressed through the multiple linear stepwise regressions as:Chl.a=0.114WT +2.120COD_Mn +17.157SiO₃^2--37.391 NO₂-N -1.946.

Abstract:To study the community structure of phytoplankton and assess the water quality in Lake Baiyangdian,an investigation has been conducted at eight typical sampling sites.This investigation showed that among the total 133 species identified,Chloro-phyta,Cyanophyta,and Bacillariophyta were dominant in the phytoplankton community.In spring, Chlorophyta and Bacillariophy-ta were the dominant phylum, and Chlorella sp., Chroomonas acuta.Uterm.and Microcystis incerta Lemm.were the dominant spe-cies.The density of the phytoplankton ranged from 496×10⁴ to 6256×10⁴ cells/L with an average of 2384×10⁴ cells/L.In sum-mer,Chlorophyta and Cyanophyta were the dominant phylum,and Chlorella sp.,Leptolyngbya valderiana Anagn.and Nephrocyti-um agardhianum Nageli.were the dominant species.The density of the phytoplankton ranged from 318×10⁴ to 4630×10⁴ cells/L with an average of 1785×10⁴ cells/L.According to the comparison between this investigation and the previous two ecological inves-tigations since 2005, the abundance of the phytoplankton has increased significantly.The index of Carlson nutritional status and the dominant genus assessment revealed that the majority water was eutrophic in the Lake Baiyangdian.

Abstract:Spatial-temporal variation trends of Chlorophyll-a concentration in Lake Dianchi were analyzed based on MERIS data.First,three popular retrieval algorithms of Chlorophyll-a concentration were calibrated by field measurements.It was found that three-band model was the best one with higher estimation accuracy.Then, the optimized three-band model was applied to 57 MER-IS images from 2003 to 2009 which were pre-processed through geometric correction,atmospheric correction,etc.At last,a series of maps about Chlorophyll-a concentration distribution of Lake Dianchi were produced.The result showed that Chlorophyll-a con-centration was rising slowly with a periodic fluctuation in Lake Dianchi.During a year,Chlorophyll-a concentration showed a de-creasing-increasing-decreasing pattern,where the minimum appeared in February and March,and the maximum occurred within September and November.Regarding to spatial distribution,Chlorophyll-a concentration was higher at the edge and the north of Lake Dianchi,which are close to the Kunming city and small towns.In addition,the higher Chlorophyll-a concentration was,the more obvious the spatial variation was.

Abstract:During April and May in 2010,the primary production in the Xiaojiang River backwater area,Three Gorges Reservoir was measured using the black-white-bottle method.The distribution features and relationships with light intensity,chlorophyll-a concentration(Chl.a),water temperature and partial pressure of carbon dioxide(pCO₂ ) were studied.The results showed that the gross primary productivities(GPP) were 1927.5 mg O₂/(m² ·d) and 1325.0 mg O₂/(m²·d) in April and May,respectively, the average value was 1626.3 mg O₂/(m²·d).The gross respirations(GR) in the two months were 1037.5 mg O₂/(m²·d) and 1062.5 mg O₂/m²·d,respectively,and the average value was 1050.0 mg O₂/(m²·d).The gross net productivities(GNP) in the two months were 890.0 mg O₂/(m²·d) and 262.5 mg O₂/(m²·d),and the average value was 576.3 mg O₂/(m²·d).Ratio of GPP/GR were 1.86 and 1.25.These indexes suggested that the Xiaojiang River was autotrophic in the spring season.Pri-mary productivity(P) in each depth and the ratio of productivity to respiration(P/R) had similar vertical distribution feature, showing that the maximum values occurred near the surface and they decreased with depth.Correlation analysis showed that light intensity(I) and Chl.a were significantly positive correlation with the P.Equations of the linear regression model P with Chl.a and with I were respectively:P=0.154 Chl.a -0.278,with coefficient R2=0.570,and P=0.001I -0.013,with coefficient R²=0.942.

Abstract:Effects of temperature(15℃, 20℃, 25℃ and 30℃) and Scenedesmus obliquus density(0.75×10⁶ , 1.5×10⁶ , 3.0×10 ⁶ and 6.0×10⁶ cells/ml) on life history parameters including net reproductive rate,intrinsic rate of population increase, genera-tion time,life expectancy at hatching and proportion of mictic offspring, and morphotype in offspring of two Brachionus diversicornis morphotypes were studied by means of individual culture.The results showed that at the four temperatures,the survivorship be-tween the two B.diversicornis morphotypes was similar.The fecundities of the equal-spined rotifers at 15℃, 25℃ and 30℃ were significantly higher than those of the unequal-spined rotifer.Each of the life history parameters between the two B.diversicornis morphotypes was similar,except that the generation time of the equal-spined rotifers was longer than that of the unequal-spined roti-fers at 30℃.The survivorship,the fecundity and each of all the life history parameters between the two B.diversicornis morpho-types were also similar at the four food densities.All the intrinsic rate of population increased,the generation time and the life ex-pectancy at hatching of the two B.diversicornis morphotypes responded differently to increasing temperature,but food density only affected the net reproductive rate and the intrinsic rate of population increase of the equal-spined rotifers significantly.The net re-productive rate of the equal-spined rotifers at algal density of 6.0×10 6 cells/ml was lower than that at both 0.75×10⁶ and 3.0×10 ⁶ cells/ml,and the net reproductive rate at 1.5×10⁶ cells/ml was similar with that at each of all the above-stated three food densities.The intrinsic rate of population increase of the equal-spined rotifers at 6.0×10⁶ cells/ml was lower than that at 3.0×10⁶ cells/ml,but both of them were similar with those at 0.75×10⁶ and 1.5×10⁶ cells/ml.At each of the four temperatures and food densities,the two B.diversicornis morphotypes produced both equal-and unequal-spined offspring.Only at 25℃,the propor-tion of equal-spined offspring produced by the equal-spined mothers was higher than that produced by the unequal-spined mothers.However,at each of all the four food densities,the proportion of equal-spined offspring produced by the two B.diversicornis mor-photypes was similar.Temperature affected the proportion of equal-spined offspring produced by the equal-spined mothers signifi-cantly, but food density did not affect the proportion of equal-spined offspring produced by both the equal-and unequal-spined moth-ers.The proportions of equal-spined offspring produced by the equal-spined mothers at 15℃ and 25℃,and 20℃ and 30℃ were similar,respectively,but the former two were higher than the latter two.

Abstract:To characterize the nitrogen uptake by phytoplankton and its relationships with phytoplankton community structure and enviromental factors,we measureed the uptake of ammonium,nitrate and urea by phytoplankton community from different areas of Lake Taihu in mid-May, 2010,using the ¹⁵N-tracer technology.The results showed that:Uptake rate of ammonium was highest for all lake areas,accounting for 62.8% of the total nitrogen uptake.The uptake rates were 0.181-1.575, 0.004-0.118 and 0.043-1.116μmol/(L·h) for ammonium,nitrate and urea,respectively.Phytoplankton communities preferred uptaking ammonium in Meiliang Bay,Lake Center and Wuli Bay and the uptake rates of the three forms of nitrogen were arranged as follows:ρ(NH₄) >ρ(UREA) >ρ(NO₃).However, phytoplankton community in Xukou Bay preferred urea to ammonium and the uptake rate of urea was the highest,the uptake rate of nitrate was the lowest.When concentrations of nitrogen are high,phytoplankton abundance and com-munity structure are likely important factors determining the nitrogen uptake by phytoplankton community in Lake Taihu.

Abstract:Phytoplankton and environmental factors at the estuary of Maixi River in Baihua Reservoir were investigated monthly from July 2009 to June 2010.Results showed that there were 66 species(genus),which were mainly composed of the chlorophyta,ba-cillariophyta and cyanobacteria.The phytoplankton community was dominated by Pseudanabaena limnetica in summer and fall and by Cyclotella meneghiniana in winter and spring.The abundance of phytoplankton ranged from 1.17×10⁴ to 3.35×10⁷ cells/L.The minimum phytoplankton abundance occurred in April of 2010,and the maximum occurred in July of 2009.The phytoplankton abundance composition was dominated mainly by cyanobacteria from April to September, but by bacillariophyta and pyrrophyta from October to March.Canonical correspondence analysis showed that temperature was the most important driving factor in regulating the composition and feature of phytoplankton community at the estuary.Nitrogen and phosphorus were the second important driving factors for the structure of phytoplankton community.Euglenophyta and a majority of cyanobacteria were affected by water tempera-ture and turbidity,but chlorophyta and bacillariophyta were affected by the concentrations of nitrogen and phosphorus among these environmental factors.

Abstract:Four zooplanktonic investigations were carried out from November 2007 to October 2008 in Lake Xiliang.Totally,224 species of zooplankton including 112 species of protozoa, 90 species of rotifer, 15 species of cladocera,and 7 species of copepoda were found.The zooplankton species ranged from 75 to 111,with the lowest value(75) occurring in winter,and the highest one (111) in autumn.The density of zooplankton was the highest in winter(126731ind./L),and the lowest in spring(71356ind./L).The densities of zooplankton in summer and autumn were 109743ind./L and 107650ind./L,respectively,and the abundance of protozoa and rotifer were on predominance.The structure of zooplankton community was analyzed in relation to water quality pa-rameters by canonical correspondence analysis(CCA).Temperature,pH,water depth,and the concentrations of TP,COD and DO were strongly correlated with the zooplankton community structure.The parameters that demonstrated a strong correlation with the zooplankton community structure differed among seasons, suggesting that the seasonal variations of zooplankton community struc-ture were related closely to both the water temperature and water trophic status in Lake Xiliang.

Abstract:The SCE-UA global optimization method was used for the Xinanjiang model parameter calibration on the Yuetan basin.The results reveal that the parameter optimization results are stable when using the ideal calibration data.However, for the observed calibration data,SCE-UA method can't get the only and stable parameter set for sure;In the Xinanjiang watershed model for daily simulation,the Water Quantity Balance Error and Deterministic Coefficient are two best objective functions and in the Xinanjiang watershed model for hourly simulation,the Absolute Logarithm Error is the best objective function;In order to get the stability pa-rameter set,more than 12 years' actual data is needed;then the objective optimization theory which advanced by ZHAO Renjun has been introduced and combined with the SCE-UA method, and the results reveal that the parameter optimization results are more sta-ble than the way that didn't use this theory.

Abstract:Hydraulic model of Huaihe River with flood diversion and flood retarding areas was developed for flood forecast.The in-put flood discharge hydrograph from the main channel to the flood diversion area is estimated with the fixed split ratio of the main channel discharge.The Muskingum discharge routing method is applied in the flood diversion area,and outflow can generate only after it reaches full storage.The flood flow inside the flood retarding area is calculated as a reservoir and inflow and outflow are cal-culated based on the water balance equation.Taking complex river basin between Wangjiaba and Lutaizi stations with flood diver-sion and flood retarding areas of Huaihe River as an example,with taking the Linhuaigang Project as inside boundary in flood rou-ting,Hydraulic model of Huaihe River based on one-dimension hydraulic model was developed.In order to testify the performance and rationality of the developed model,the representative flood events from 2003 to 2008 were forecasted with the developed hy-draulic model.Results show that the developed model performs well and is reasonable.

Abstract:The quantitative analysis of the land use change and its transformation relationship in the Taihu region during 1990-2008 was put forward,using GIS and RS technologies, based on the remote sensing data and land use data, taking the administrative di-vision as the assessment units.The assessment model comprising a landscape disturbance index and a land use sensitivity index was established on the base of land use change and landscape perspective to assess the landscape ecological risk characteristics of tempo-ral and spatial change in study area.The results showed that the distribution of ecological risk had higher associated with the inten-sity and pattern of land use change.As a whole, the landscape ecological risk had been rising in the past 18 years;the area of high ecological risk was expanding.Due to the physical characteristics and social economy,the spatial variation of landscape ecological risk was significant.The low risk areas distributed mainly in the hilly and mountainous areas,the medium risk areas was mainly in the agriculture developed plain area,and the higher and highest risk areas distributed at the economically developed areas around the lake.The sources of landscape ecological risks were different, and variable land use types also had different risks.The farmland and construction land were the main risk source of the whole region.As the regional development, the ecological risk from the water and woodland were increasing steadily.

Abstract:A nine-day observation on the process of vertical stratification of physicochemical variables was taken from 24th July to 1st August, 2010 in Lake Taihu,a large shallow lake of China.Frequent stratification processes occurred during the 9 days.But the stratifying state was unstable,and normally last less than 1 day.The main factors causing stratification were water temperature and its diel variation, cyanobacterial bloom scum and wind-induced wave disturbance.The vertical difference of water temperature-may reached 3.94℃,which was mainly influenced by diel variation of air temperature and solar radiation.And the stratification of water temperature was the basic factor causing the stratification of dissolved oxygen,electric conductivity,and pH.Cyanobacterial bloom scum could cause the strongest stratification, which could cause vertical difference of 8.67mg/L of dissolved oxygen, 48μC/cm of electric conductivity, 1.49 of pH, 9.1μg/L of chlorophyll-a and 26.5NTU of turbidity.Besides turbidity,stratification of physicochemical variables became weaker with the increase of wind speed.No stratification happened during strong wind period in which of wind speed over 6m/s,while it often happened during weak condition in which of wind speed less than 2m/s.The study indicated that,stratification processes could frequently short-term occurred in large shallow lakes,and might have potential influences on the processes of biological activities and exchange on air-water interface and water-sediment interface.

Abstract:Using ETM⁺ remote sensing images acquired on Dec.28 in 2001, March 18, July 24, Sept.26, Dec.15 in 2002, re-spectively,this study extracted the information of seasonal changes of the number and areas of lakes and analyzed the statistical char-acteristics and spatial distribution of them.The following conclusions were drawn.Firstly,the number and total area of desert lakes showed a decreasing trend from spring, summer, autumn to winter in the first year and regained the original condition gradually in the next spring.Secondly,the seasonal variation of lake area displayed an obvious characteristic that the atrophic and increased area of lake present a distribution of gathers and continual pieces and gradual changes in the spatial distribution showed in some time section.The automatic weather observation station of Badain Jaran Desert had been completed in winter in 2009.Our next focus is to study the scientific issues of lake water cycle further,water balance both using RS imagery data and meteorological observation data.