Abstract:The lake records have proved their value by providing improtant insights into how global and regional climatic events influence continental ecosystems upon which humanity is most immediately dependent.Long recored from single sites have the advantage of minimizing the effect of non-climatic variables on the cycle-to-cycle palaeoclimate study of climate proxies.The comparative study of the long core records iocated at different regions in China can provide some significant in-formation about the regiona1 differentiation of environmental evolution, and furthermore, about the Asia monsoon activities with the study on Loess plateau.However.detailed lacustrine cores studied with a span of several 1000OOa are very rare in China The available examples are only three long cor from the Zoige Basin in eastern Tibet (Qinghai-Xizang)plateau, Qaidam basin in northern Tibet plateau and Dianchi basin in Yunnan plateau respectively.The result has shown that there distinctively exist 3 stages since Mid-Pleis-toce ne, i.e.780-48OkaBP, 480-160kaBP, 160-OkaBP for each of them the enviro nment was of different and special characteristiea in different regions of China.The result has also shown that the Tibet plateau has played a major role on the differentiation process.The comparison study is still in its infancy and m ore long cores are needed for us to probe into the uplifting of Tibet plateau and As Jan monsoon evolution.

Abstract:When simu1ating the wind-driven flow of a lake.the wind field above the water surface is akey factor that influences the precision.The complicated terrains around a lake.such as moun-talns, often result in unsymmetrical distribution of wind velocity and direction above lake surface, so water flow pattern must be changed by the terrains.In this paper.a 3-D micro-meteorologymodel for lake scale is built up to compute local wind affected by the shelter of hilly terrains Based on this, the flow pattern of Dianchi Lake under rea1 terrain conditions is simulated with a 2D wind-driven current model.and the flow pattern in this case is compared to the flow fields under uniform wind and artificially modified wind respectively.The result shows that if the wind—driven flow in Dianchi Lake is simulated after obtaining the local wind field according with realmeteo rological characters of lake area from the meteorology model, the simulation result can aCCU.rately reflect the general character of water movement in Dianchi Lake.

Abstract:Field observations on internal waves in the North Basin of Lake Biwa were carried out during Biwako Transportation Experiment (BITEX'93). Rotary spectrum analyses of current show that beside the fundamental internal Kelvin waves, in the top epilimnion, there were waves rotating clockwise witb a period of 24h wbieh are thought to be wind-induced oscillations. In the tbermocline, pure Poincare waves of their first mode were found, which were the governing mode at the depth. The Poincare waves made the current at that depth rotate clockwise with a period of 16-18h. In (he hypolimnion bottom, seiehes with a period of 11 h were found which were not rotating and purely gravitational. All of these illustrate that there are different kinds of governing internal waves In different vertical zones. Internal wave research by current measurement, an important method, can distinguish the Poincare waves from internal seiches. The earth rotation effects are responsible for the current rotation, as well as wind rotation phenomena. Thus, the important physical factors on internal wave dynamics during stratification period in the lake seem to he wind stress stratification, Coriolis force and shore constrained.

Abstract:A numerical model coupling atmosphere with hybrodynamics is set up in this paper to study the gyres mechanism m Lake Biwa, Japan. Some results arc obtained as follows:1)There exists a positive wind vorticity field over the lake, and also a positive wind divergence field in daytime and negative one in night This special atmospheric boundary layer of Lake Biwa catchment can generate a typical land-lake breeze, this local wind system can induce and maintain a weak but stable counter-clockwise gyre in north lake during period of thermal stratification. 2)When considering inbomogeneous wind field. the gyres formed in the lake can sustain longer and be more stable than that only driven by homogeous wind over the lake. 3)The local wind system can produce a typical horizontal distribution of water temperature, i.e. water temperature higher in shallow water, lower in deep water.

Abstract:In the light of storm flood properties, analysis and computation ave carried out about four heavy flood events ever occurred in the Poyang Lake area using four mbthods, i.e.area ratio method, adjusted total inflow method, tingle-source model(the current flood forecasting scheme) and the Xin'anjiang Model(three-source), for the sake of river basin flood control planning The effect of the changing ratios of water surface to land surface corresponding to diferent water stag-es on i.e off generation and flow concentration is analyzed.and the estimation formulae in the Xin'an jiang Model are modified.Results show that conceptual rainfall-run of models can properly simulate the flood processes, and that under reasonable conditions, simplified methods can also prod uce satisfied results.The applicability co nditions of different methods are given through com-parative analysis.

Abstract:Taihu Lake is one of the five Iargest fresh 1akes.Located at the center of Taihu Lake Basin and controls the flood situation of Taihu Basin The main flood period of Taihu Lake and Basin is determined by plum rain period, which normally starts on June ll and ends on July 20.After an-alyzing the plum rain period in history, the highest water level of Taihu Lake in heavier flooding years, inflow and outflow around Taihu Lake in the past 22 years.the flod situation of Taihu Lake has changed, which is influenced by precipitation distribution, discharge change, and the operation of main channels such as the Taipu River and the Wangyu River.The decrease of dis-charge of Taihu Lake is primarily resulted from the accretion and reclaimed Land in East Taihu Lake.Studying the operational rule of main channels, dredging the mouths of the Taipu River and the Wangyu River.and reinforcing of the Around Thu Dyke are main measures to control flods of Taihu Lake Basin.

Abstract:Brachionus calyclfurus(Rotatoria)were cltured on single alga Chlorella pyrenoidosa, Oocystls elliptica, and mixed at densities of 0.25.0.5, 1.0.and 2.0×10⁶>.celis/mL, respective-ly.Experiments were conducted at 25℃ in a photoperiod(LD18:6)with light intensity about 4000.lx.The results show that the average values of eggs produeed in medium of Chlorella pyre-noidosa were 6 00.6.75, 11.20.and 11.40ind..respectively.The percentages were 23.06%.22.41%-8.52% ad 4.85%.respectively.The mean eggs increased and the percentage de-creased with the increases of food concentration.The mean eggs were 3.33, 3.33, 2.33, and 3.83ind.in medium of Oocysti elliptica,the percentages were 36.11%, 30.55%, 20.83% and 12.50%, respectively.The mean eggs per female cultured on mixture medium (mixed Chlorella with the same quantity Oocystis)were 5.00, 4 67, 3.67 and 4.67 ind..respectively.The percentages of mic-tic females were 28.90%, 25 00%, 16 67% and 0%, respectively.When rotifer growing on medium of chlorella at densities varied from 0.125×10⁶>.to 8×10⁶.cell/ml, the mean eggs increased gradually from 4.17ind.to 13.67ind., and the percentages of micticfemales decreased from 32.00%.25.00% to 4.48%.In range of 4.0×10⁶.to 8.0×10⁶.cells/ml,, the mean eggs decreased to 8.33 ind.(8.0×10⁶.cells/mL excluded)and the Percentage of mictic fem ale incread to 48.O0% again.The correlation between mictic percentage(Y)and concentration of fod(X)was signifi.cantly negative in medium of Oocystis(r=-0.97).and in mixture(r=-0.99).the equation of regression y=37.3148-13.1348X (in medium)and Y=33.1778-16.5683X (in mixture).

Abstract:The oxygen consumption rate and asphyxiaton point of Leptobotia elongata (Bleaker)are studied by Krogh's method The oxygen consumption rate(Y')of the fish decreases with the body weight increasing, while oxygen Consumption(Y)increases with the body weight(W')in-creasing under water temperature 22-23℃.The regretion line may be represented by the fol-lowing equations respectively:Y'=186.576W^－0.2043 and Y'=0.186W^0.7962.The water ternpera-ture affects rate of oxygen cons umption in Leptobotia etongata, it increases gradually with water temperature rising at 13-3O℃.Changes of oxygen consumption rate are bigger at the ranges of low temperature(13-23℃)and high temperature(28-30℃), but amount of increase in oxy-gen consumption rate and metabolism is relatively lower under water temperature 23-28℃.Daily fluctuation of the oxygen consumption rate was also observed in the experiment The oxygen consum ption rate Was the highest at 2:00.a.m., the lowest at 4:00.P.m.Asphyxiation point of the fish is 0.94-1 06mg/L when the body weight of the fish is 38-59g.0.62-0.70rag/L when body weight is 250-320g.

Abstract:The short-snout icefish, Salangichthys(Neosatanx)tangkahkeii taihuensis Chen, is one of commercial fishes in Taihu Imke.Investigation on the embryonic development of this sort of fish was made during the year 1981-1983.The ovarian egg of this fish is demer, colorless, spherical or spheroidal, measuring 0.53-0.82mm in diameter, with extem a1 filaments.The bends in the lake is the spawning ground.Fertilized egg hatching takes 312 hours 15 minutes at the water temperature of 5.9-14.2℃ The just hatched larva is 244mm in tota1 length.with the melanopho rea around the aDus open.Them yotome numberis 42+13:55 In 3 days, larva's mouth begins to open and the air bladder is abounded by gas.The string melonophorss are scattered on the yolk and above the ventral fin fold In 5 days.the yolk is al-most entirely consumed and the 1arve attained 4, 60mm in total 1enth.In 9 days.the yolk is en-tirely consumed.In 12 days.the lalva dies off.It has been found that the fertilized eggs could be used in transplanting.As to lakes and res-ervoirs where there is no ice fish, great economic benifits can be achieved after the transplantation of Salangichthys(Neosalanx)tangkahkeii taihuensis Chen succeeds.

Abstract:Dealt with the growing debth of macmphytes roots.spatial distributions of microorganisms and enzyme in artificial wetland and comparison of removal rates of contaminants in different depths of artificial wetlands.the better purifying space in artificial wetland wastewater treatment system has been discussed.From studies on the artificial wetland with cattail(Typha angustifilia)and rush(Juneus effusus), roots of macmpyhter are distributed mainly over 25cm up surface in wetland, spatial distribution of micro rganisms is as follows.The numbers of 5-10em depth are more than the 20cm depth's and further more thanthe 35cm depth's.The activity of phosphata, glucan de-hydratase and proteinase in surface is higher than 20cm depth's.In winter, the performance of purifying wastewater of the Wetland which deeps 20em shows almost no difference with the wetland which deeps 60cm.It may be deduced that there is a better purlfying space in the upper level of artificial wetland for wastewater treatment.

Abstract:In shallow lakes.aquatic plants play very improtant roles in primary production and environ-mental protection.On the other hand.it can also cause silting-up by adding large amount of plant material to the lake bottom and release pollutant to the lake water when it dies and decays.The functions of aquatic plants car/be regulated reasonably by manipulating the structure and species composition of aquatic vegetation of the lake.In East Tathu Lake, more than 97% of the lake surface was covered by aquatic plants, which abso rbed 3916t nitrogen and 496t phophorous from the lake in a year to produce 1120325t plant biomass(fresh weight) About 599295t plant bio-amsswas harvested from thelaketo remove 198lt nitrogen and 296t phosphorous, equalto 28% of the external nitrogen load to remove 57% of the extecna1 phophorolls load of the Inke.There was stil1 521030t plant biomass remained and decayed in the lake which caused serious water Pollution and siliting-up of the lake basin Elodea Nuttallii was introd uced to the lake in 1986 and transplanted on a large scale in the past ten years.About 50000t of Elodea Nuttallii were har-vested as fish fod der in 1993 An experiment was carried out successfully to replace Zia lati in the 1ake with submerged plants.There alre still a lot to do to complete the task of reason-able regulation.

Abstract:The aubstance exchange across the water-sediment interface in the north Taihu Lake was studied under the condition of 25℃.The results show that the release levels of nitrogen.phos-phorus and COD in Wuli Lake area are distinctly higher than those in Meiliang Bay, and the aver.age release rates of their NH₄⁺-N, DTP and DCOD are 158.2.2.05, and 27.8mg/(m²·d).Re-spectively.In the northern part of Meiliang Bay, formal nitrogen negatively releases and howev-er, DTP and DCOD release rates are separatively 0.584 and 8.9mg/(m²·d) Morever, the ex-changable amount of the form al nitrogen, phosphorus and DCOD on the water-sedim ent interface has obviously to do with content of the total nitrogen, total phosphorus and organic matter in the corresponding sediments.On the basis of internal pollution source analysis, restraining the release of nitrogen, phos phorus and COD in the part lake area is considered to be one of the important measures to control the water pollution and eutrophication of Taihu Lake.

Abstract:Some physical and chemical characteristics of sediment in West Lake.Hengzhou are dis-cussed in this artide Preeipitation trial test shows that particles with diameter between 0.067mman d 0.0029mm constitute 80.6 percent of the total sediment in West Lake, end particles with diameter below 0.0029mm constitute 4.3 percent of the total, and suspended particlas can appar-endy affect the diaphaneity of water.Sediment in West Lake is situated in a neutral an aerobic sta-tus(pH=6 60-7.40;Eh=-3mV to 167mV), Do on the interface between water and sedi-ment approximately equals lmg/L Biology production number(BPN=0.4836)and IG-totalnitrogen ratio(IG/TN=22.54-30.71)of sediment show that West Lake has a characteristic of both hyperproducfive and high humans content.Principal Component Analysis(based on sediment parameters)demonstrates that the precursor of West Lake sediment is bog, and sediment in Xiao-nan Lake is apparan tiy different together areas due to the diversion operation.

Abstract:A new methodology for the division of water environmental functiona1 zones in Jianhu Lake, Zhajiang Province, is proposed.The division process is further designed.By means of the aerial photograph interpretation, the lake-river system's cause of formation investagation, and sko-economic and environmental data collection, the techniques composed of overlay-mapping, water quality dus ter analysis and O.intergrated evaluation are used.Based on the area units of naturalregion, four functional zones have been setup for Jianhu Lake water environment.The study results show that the suggested methodology is an effective way to solve functional zones division, because it not only has the semi—quantitative advantage but also can provide scien-tific basis for making rational use of water resources and protecting water quality.The divisional results of four functional zones have been applied successfully to Jianhu Lake environmental capac-ity and water quality planning, to the daily management by local environmental admnistrative depayments.

Abstract:Use of phosphate-containing detergents results in the plunce of phosphorus in sewage.and the phosphorus contributes to high phos phorus levels in surface waters which can contribute to the eutrophication process In the late 1960s, the Great Lakes were heavily polluted, the United States and Cannd a looked for measures to clean them up The American action set the pattern for the world that was to ban detergent phosphates.From then on, a number of industrialized coun-tries, such as Japan, Western European countries, have reduced or banned phosphates in deter.gents.Up to now, there has been no convincing evidenee to support the view that the removal of ohosphates from detergents can result in the cbange in the eutrophication state of a body of water,To prevent eutrophication, more than 90% of the phosphorus from alI souses in wastewaters must be removed.But in most eases, the reduction which can be achieved by restricted or banned phosphates in detergents is approximately 20% of the total input phosphorus Therefore.only ad-vaneed wastewater treatment, such as biological phos phorus uptake and chemical precipitation and absorption of phosphorus by the addition of iron and aluminium compounds or lime, is the most generally applicable approach in preventing eutrophication Asummary of the historical background, effects and arguments on restricting or banning phosphates in detergents in industrialized countries are provided.It is expected that this study will cad to the basis for the regulations in China of water resource protection.