Abstract:The middle and lower reaches of the Yangtze River are one of the central areas of freshwater shallow lakes in China. Most of the lakes have been under mesotrophic or eutrophic conditions the latter are especially common in urban lakes. Human activities have played a key role in the eutrophication process from at least two aspects: continuous effluents of industrial, agricultural and domestic wastewater could add nutrient to the lake; and reclamation stone-built dikes cultivation could damage natural habitats and reduce nutrient output from the lake. The seriousness of eutrophication has aroused attention of national government. Two of the "Three Lakes" Water Pollution and Prevention Control Program that give priority to the Tenth-Five-Year-Plan of China are situated in the plain i. e.,Taihu Lake and Chaohu Lake. The nutrient status has been under a relative high level in most lakes. The eco-environmental questions in lakes are conspicuous even though local governments have taken some measures to prevent further environmental deteriorations. Steps dealing with external nutrient loadings have achieved good results in deep lakes internationally while they are no longer so effective in shallow lakes because we lack a through understanding of mechanisms of eutrophication in shallow lakes. World-acknowledged experiences of shallow lakes eutrophication control have proved that eutrophication still prevails even though area-source nutrient loading to the lake could be reduced to a minimum level,Internal sources from the sediment may certainly relate to the maintenance of eutrophication, The kinetics of water could re-suspend sediments and effect the nutrient release process underwater light intensity and primary production as well To control eutrophication in shallow lakes must take both external loading of nutrient and internal loading into consideration. One of the effective measures for internal loading is the restoration of aquatic plants in order to inhibit the re-suspension and sediment release. Researches on the experimental ecological restoration and functions of ecosystem deterioration are needed. As a result,external control on nutrient source pollution is not enough in shallow lakes; internal nutrient within lakes must be emphasized. Two techniques have been applied in internal loading control i.e.,dredging and macrophytes restoration. The former requires a complete knowledge on the trophic history in lake ecosystem so that an exact schedule on the scope and depth of dredging could be determined lest newlyexposed sediments become fresh internal release source. The latter could inhibit sediment suspension under dynamic conditions and absorb nutrient within lakes so as to diminish nutrient load as well. Macrophytes flourishing and algae bloom outbreak are two aspects of eutrophication in lakes. Why macrophytes-dominated lake could be evolved into an algae-dominate one? How to revolve the process? Future macrophytes restoration must answer them. Researches abroad prove that a macrophytes-dominated lake could be turned into an algae-dominated one under strong external disturbances and steady high lake level; once algae-dominated,the lake would come to another steady state for nutrient cycling To restore macrophytes and get cleaner water,this cyclic process must be broken down. Consequently,it is strongly recommended that researches on the mechanisms and control of eutrophication in shallow lakes be initiated,so that a theoretical and technical basis could be provided for future launching national programs on eutrophication control in China.

Abstract:Up to now, all the projects listed in the Taihu Basin Integ rated Plan have been completed, which broughtin 9.2×10⁹ Yuan benefit during the 1999 flood season, equivalent to the total amountof investment for all the projects.The gains of the Taihu Plan lie in its extensive consideration on 1)f lood control benefits, 2)coordination and balance of local governmentinterests, as well as on 3)water supply, navig ation and environmentalimprovement.Nevertheless, the plan fell shortin insuf ficient demonstration of engineering parameters and incomplete satisfaction for all the local requirement s-some of them are too exacting-which need further improvement and amendments to the plan.

Abstract:Based on the rubidium to strontium (Rb/Sr)ratio, carbonate (CaCO₃)content and organic carbon concentration (C_org)record in lake sediments from the Daihai Lake, Inner Mongolia, dated by AMS-¹⁴C and ²¹⁰Pb, the climatic and environmental change process was reconstructed since the last 2, 200 years, including two important climate events, i.e.the Medieval Warm Period and Little Ice Age.An increase Rb/Sr ratio but a decrease both CaCO₃ and C_org correspond to a cold period, and vice versa.In this paper, we first sug gest that there existed the Medieval Warm Period in the northern China during 900-1200a B.P.by a high-resolution lake record characterized according to lower Rb/Sr ratios and hig her CaCO₃and C_org concentrations in the sediments from a single watershed, which a warm and humid environment was demonstrated by signif icantincrease of chemical weathering and by a progressive increase of biologic productivity, and by a high lake level.The Medieval Warm Period has no tonly an inner climatic fluctuant, but also the strongest chemical weathering during the last 2, 200 years, which are indicated by a high-resolution natural record in northern China.Furthermore, the Medieval Warm Period in northern China is contemporaneous with the worldwide eventidentified in the lakes, oceans, land mollusk sequences, polarice cores, pollens and historical documents.

Abstract:Goulu Co is located in the Hoh Xil District Tibetan Plateau. By analysis of carbonate contents grain size and C value of lacustrine sediment in Goulu Co the enviromental change processes during the past 40 years are revealed. With the temperature rose,rainfall dropped. Moreover the meteorological data in nearby stations (Wudaoliang and Tuotuohe) are compared.

Abstract:Bosten Lake isone of the biggest freshwater lakes in China.On the basis of in situ hy drological and hy dro-chemical data of Bosten Lake, this paper discusses the annual and seasonal change of water saltof Bosten Lake in detail.During the past 40 years or so, The lake water has undergone an annual changing process and the seasonal change is closely related to the water discharge coming from Kaidu River thatis the largest water source supplying for the Bosten Lake.The farmland drainage contains salt around the Lake.The change of mineralized deg ree in the lake is negatively correlated with the water levelin the pasr 40 years, i.e.when the water levelis lower, the lake mineralized deg ree is higher.With the increase of ion content, Ca²⁺ and Mg²⁺ increase slow ly, while the contents of SO₄^2-, Cl^-and K⁺+Na⁺ show markable increase.The descending ion contentorder is SO₄^2->Cl^->HCO₃->K⁺+Na⁺ >Mg²⁺ > Ca²⁺ >CO₃^2-, and its proportion may differ with the sampling positions in the lake.The hydro-chemical ty pe is SO₄^Na.The lake water sources and lake water circulation are the main factors that have impacts on the change of lake water quality.The measurement for improving Bosten lake water eco-environment are suggested as follows:farmland irrigation quota should be reduced, river water amount flowing into Bosten Lake be promised, the groundwater resources utilization in the Yanji Basin be sped-up, and the lake water circulation intensity streng thened.

Abstract:Chaohu Lake is one of the biggest freshwater lakes of China.This study was conducted to establish correlations between reflectance spectra and contents of chlorophy ll-a in Chaohu Lake, which was in eutrophic status.Reflectance spectra were measured during November, 2001 by using ASD FieldSpec HandHeld radiometer.Water samples for chlorophyll-a measurements and dominant algal species determination were collected at the same time.The features of the spectral reflectance of the lake were discussed.The correlation between the spectral ref lectance of single band and the contentof chlorophyll-a was low.The reflectance ratio of R_705nm/R_680nm and the reflectance first-derivative of 690nm were found to be significantly correlated with the contents of chlorophyll-a, and the r² gained using the reflectance ratio was higher than gained from the reflectance first-derivative of 690nm's.

Abstract:The main heavy metals in the sediments of Yilihe River, Yaihu Basin were analy zed with ICP analy tical method.The comprehensive pollution indexes of heavy metals were calculated by root mean square on the backg round of the lower layer sediment sample in the inletof Yilihe River, and the polluted situations were evaluated according to the classified pollution levels.The results showed that the sediments of Yilihe river and its inlet were average in light polluted situation.The north branch streams were not polluted, the south branch streams were in light polluted, and the trunk river, the most polluted, was in average partial middle pollution, but the individual site in the trunk was in heavy polluted situation.Of all the metals Cu, Zn, Cd and Pb were evaluated to be higher pollution indexes, of which only Cd contents exceeded the one-class natural backg round level of China, being Cd-type pollution.The pollution reason was inferred to be relative to the pollutio n discharge of manufacturing industries of cement, nonferrous metal smelt plants.

Abstract:Based on ¹³⁷Cs technique, a quantitative model for soil erosion has been established, and the amountof soil erosion and nutrients losses have been calculated.The resul ts showed that the average amountof soil erosion of various profiles in forestis 1313.6 t/(km²·a), and the erosion in vegetable land is much hig her, so there is soil erosion in hilly region of Taihu Basin.The main factors affecting soil erosion are vegetable cover and cultivation, and the sortorder of soil erosion amounton different landforms from high to lowis as follows:vegetable land >middle slopping hill with masonpine >middle slopping upland with bamboo >top land.The nutrients loss is correlative with soil erosion, and the average loss for organic matter, total nitrogen, total phosphorus and total potassium in forestis 28.29, 1.38, 0.35 and 16.76 t/(km²·a), respectively.Therefore, it's time to pay attention to soil erosion in this area, and take some measures toreduce its effecton soil fertilizer and water quality in Taihu Basin.

Abstract:The Comparison of the heavy metal binding properties and tolerance was studied between wild type and transgenic strains which expressed a foreign MT-like gene from Festuca rubraL Merlin in Chlamy domonas reinhardtii.The results showed that the cadmium binding capacity of transgenic strain was 1.5-fold of the wild type in low cadmium concentration(5-10μmol/L), however, there was not marked difference of heavy metal binding capacity in high cadmium concentrtion (30-50μmol/L).Itindicated that the difference of heavy metal binding capacity was from active uptake between transgenic strain and wild type.On the other hand, transgenic strain also showed more higher tolerance than wild type when they were cultured in 150μmol/L copper solution medium and 600μmol/L cadmium agarmedium.Transgenic strain was used to treat wastewater, it could enhance more than 10% of copper removal efficiency than wild type.

Abstract:Jinji Lake is located in the developed area of Suzhou City, Jiangsu Province.The area of Jinji Lake is about 7.38 km², with mean water depth of about 1.6 m and a volume of about 0.12×10⁸ m³.According to National Environmental Quality Standards for Surface Water of P.R.China, the water quality in Jinji Lake is about Grade IV-V which is mainly caused by the industrial, agricultural and sewage pollution around Jinji Lake.The municipal government of Suzhou City decides that Jinji Lake will become a lake for of sight seeing near the city area, so that the function of the lake will be changed from irrigation to the entertainment.In order to improve the water quality in Jinji Lake, the comprehensive measures is planned to putinto the use in Jinji Lake.The environment benefit and economic expenses of the engineering to improving the water quality in Jinji Lake have been analyzed comprehensively in this paper.The engineering can change the water quality in Jinji Lake from Grade IV-V to Grade III (National Environmental Quality Standard for Surface Water, PRC).As cauculated, the expected economic expenses is about 0.92 to 1.62 Yuan RMB/m³.If we consider the rise of landed estate and travel income once the lake water quality has been improved, the economic expenses would be lower.In conclusion, the engineering could bring out obvious environment and social benefits, and the economic expenses is also reasonable.

Abstract:Hongze Lake is one of the five biggest frestwaterr lakes of China.Based on the monitoring environmental data in 1990-2000 in Hongze Lake, a database of lake water quality and spatial distribution was established.Af ter analyzing the correlation matrixes of water quality indexes and sampling points, the spatio-temporal correlativity of water quality indexes were revealed by using the software of Origin and GIS etc.The temporal and spatial distribution characters of water quality indexes in Hongze Lake were also given.The result showed that there existed certain spatio-temporal correlativity of water quality indexes in Hongze Lake;and the spatiotemporal relativity of water quality indexes had been strongly disturbed by human activities.Hence the nature reserves in wet lands should be located in the areas with low spatio-temporal correlativity.

Abstract:Niushan Lake (114°32' E, 30°19' N),situated in Hubei Province of China is a shallow macrophyte lake in the middle reachesof the Changjiang (Yangtse) River with a total surface a.ea of 40 km².Age growth and reproduction of Rhodeus ocellatus from the lake were studied during April to June 1999.Annuli on scales were clear and could be used as valid indicators of age.The population of the bitterling comprised only one age group and the maximum of life span for both sexes may be less than 2 years.The sex ratio of males tofemales was 1.59:1 (n=332) with significant difference from 1:1 (X²test,X_c² 16.94 P<0.01) The relation-ship between total length n=(TL, mm) and body weight n=(W, g) for sexes was expressed by the equation lnW=-11.945+3.163 lnTL (n=238,r=0.98,P〈 0.0001).Slope of the equation was significantly greater than 3 (P〈 0.01).This may suggest an allometiic growth. The bitterling were multiple spawners reaching maturity in the second year.During spawning,both sexes exhibited secondary sexualcharacters.Minimum size was 26 mm in total length and 0.216 g in weight for males and 32 mm and 0.393 g for females.Mature eggs were cucurbit-like form with mean size of 3.31 mm long (n=23,SD=0.14).Fecundity per female averaged 61 eggs (n=46,SD=18) with a range of from28 to 119.In addition to that, There wassignificantly correlation of fecundity (F,eggs) to total length (TL,mm) or body weight n=(W,g)(p〈 0.0001),and the relationships were expressed by the equations F=26.1+83.2 W (n=52 r=0.73) F=4.78 10^-3 TL^2.537 (n=52 r=0.78).

Abstract:The practice of controlling lake eutrophication has come a long and difficult way from controlling nutrient, direct killing algae to biomanipulation and ecolog ical restoration.Although many countries have put a huge amountof money into it, little effect has been produced yet.Lake eutrophication is still a serious global hy dro-environmental problem.Toreview and analyze experience and lessons drawn from researches and practices in this regard will undoubtedly be very beneficial to the adoption of more feasible techniques in effectively controlling lake eutrophication.After a comprehensive survey into worldwide research results in controlling lake eutrophication, itis obvious thateutrophication is a typical ecological problem.Ecological problems can only be solved through ecological ways.Since eutrophication can not be quickly controlled in whole-lake scale, it's the key how to centralize technical and financial resources for controlling the eutrophication in some important areas where human production and life are g reatly affected by eutrophication.Gradually, the degraded ecosystem might be remedied;selfpurifying capability enhanced and water quality improved.A healthy lake ecosystem will be restored finally.

Abstract:Based on the investigations of bilogical resources on Dec..1999 in winter Gucheng Lake Jiangsu Province, the biomass abundance of zooplankton, hydrophyte as well as compositions and community structures are analysed.Moreover the changing tendency in 1990-1999 and the culturing capacity of fishery in Gucheng Lake are discussed.Although the water quality of Gucheng Lake belongs to Grade 3 according to national surface water quality standards for drinking water,yet the lake water is under eutrophication gradually,especially in recent years.The potential fishery yields of Gucheng Lake is estimated to be 0.8 million kilogram.Some measures must be taken to prevent the aquatic environment from further deterioration so that the biological resources be protected and utilized in a sustainable way.