Abstract:The development in large scale of lacustrine sediments or their deficiency in geologic history of the earth is closely related to the definite geostructural background and climatic conditions. According to the temporal-spatial distribution of lacustrine deposits since late-cenozoic, the evolutionary processes of macroenvironments are discussed in this paper. There exist a great number of large lakes in West China, with a thick pliocene and Early pleistocene deposits in the lakes, whereas only limited lake sediments were found in East China. This situation was resulted from the different structual movement and air circulation, with a rather humid climate in West China at that time. In mid-late Pleistocene, most of large lakes in West China shrunk quickly or even disappeared, while the tendancy of increasing and expanding of lake occurred in East China, which was evidently related to the rapid uplifting of Qingzhang Plateau and strengthening of East Asian monsoon. The lake response to in climatic zones giaciation and interglaciation since Last glacial age shows rel-ativeiy obvious differentiation indicating the influences of global, regional and local ronments respectively.

Abstract:Qinghai Lake is situated in the northeastern margin of the Qinghai-Xizang Plateau, i. e. a boundary area of East Asia monsoon with very sensitive climatic and vegetational changes. In accord with cold and semiarid climate, the vegetation zone of Qinghai Lake region belongs to high cold shrub steppe and meadow. In the provious papers based on the information of sporo-pollen assemblages by radio-carbar dating, the authors (Du et al. 1989, Kong et al. 1990) preliminary have pictured the vegetational and climatic changes in the last 11000 a. Unfortunately, vegetational and climatic succession was so short that only a little is known about the environmental changes since pleistocene. The pollen analytical investigation of 155m-deep-QH86 core from Er-longjian terrace in Qinghai Lake has been carried out. (Fig. 1) For sporo-pollen analysis on 200 samples collected from core-QH86, 90 samples are qualified for statistics. Based on the characteristics of QH86 core sporo-pollen assemblage along with ²³⁰Th dating, seven pollen zones may be subdivided in an ascending order as follows:(Fig. 2) In zone Ⅰ(342-275ka B. P.), zone Ⅱ (230-175ka B. P.) and zone V_c(83-63ka B. P.) the vegetation belongs to temperate steppe mixed by a few trees. During those periods some hydrophytes, such as Typha, myriophyllum, pediastrum boryanutn and ferns apparently increased. The climate was relatively warm and wet. It is emphasized that the vegetation and natural environment changed violently in Qinghai Lake region between 39 and 26 ka B. P. (pollen zone VI) the vegetation was dominant in a subalpine conifer forest consisting of picea, pinus Abies and etc. Such broad-leaved deciduous trees as Betula, Ulmus Quercus meight grow in conifer forest. Lakes and bogs were well developed. In contrast with zone VI, zone I (275-230ka B. P.), zone IV (175-120ka B. P.) and zone VI (63-39ka B. P.) the vegetation was represented by temperate shrub, semi-shrub and steppe, consisting of predominant Chenopodiaceae, Artemisia, Ephedra, Nitraria and Gramineae. In those periods trees, ferns and algae were obviously reduced due to dry and cold climate. It is pointed out that palynalagical evidence is still shot for some layers during 730-350ka B. P. in QH86 core. So it is necessary to make further investigations.

Abstract:The correlation between the summer drought/flood in the lower reaches of the Changjiang River and the sea temperature abnormality has been verified by many on-the-spot investigations and observed data. Since Taihu Lake basin is a part of the middle and lower reaches of the Changjiang River, it is questioned whether this kind of correlation existed in historical period. After the analysis of large amount of historical materials, the answer is positive. Finally, combining the historical materials with observed data in flood/drought factor analysis, the model of flood/drought variation in Taihu Lake basin is established.

Abstract:This paper has introduced a quantitative method of calculating the temperature effect of Poyang Lake water body. Based on thirty-year normal meteorological data observed by the weather stations in the lake area and short-period contrast exploring data obtained by the stations on both water and land. After analyzing the summer temperature effect of Poyang Lake water body, it is found that the water body may make the maximum temperature over the lake area reduced and the minimum temperature increased t but the more important is that the average temperature goes up about 0.1-1.0℃ during summer time. The maximum temperature appears in the Tangyin station located in the center of the lake with the pure water temperature effect of about 0.1-0.4℃. The effect becomes weaker gradually in all directions with an affected area being about 10-40km. Because the lake area is under the control of subtropical high, the diurnal wind velocity varies obviously, in addition to the effect of topographic features, the area affected by Poyang Lake water body during summer time is larger in south than in north.

Abstract:The karst dammed lakes in limestone area of Minshan Mountain Range, NW Sichuan, belong to a special kind of lake morphology. They developed and were formed under certain geological, geomorphological and hydrochemical conditions with bio-effects as result of rapid tufa dam gradation in stream channel. With field observation on the sedimental structure, lake morphology and water chemistry as well as optical & Scanning Electronic Microscopic observation on tufa samples from the research area, various kinds of bio-effects have been identified to exist in the process of tufa dam formation. It is shown in the general cycle model proposed in this paper that many organisms (mosses, algae and bushes etc.) with various effects (assimilation, interceptionr capillary effects trapping & bindings and shoring effect) on tufa deposition play an important role throughout the compound cycle process of tufa dam gradation (i. e. the formation of karst dammed lakes) in the stream channels in the research areas.

Abstract:The distribution of sand dune in Qinghai Lake Basin is characterized by a surrounding lake specially concentration at EEN shore. Therefore, the wind sand can enter the lake from difference directions, in fact, max. quantity of sand comes fom east t west and north directions. According to the calculation by the formula, the wind drift sand discharge of eatering the lake is about 88.708×10⁵ t/a, the silt discharge of empting the lake by rivers about 3.577×10⁵ t/a, and the falling dust discharge from air about 3.036×10⁵ t/a, The sandy materials entering the lake were transported by the lake wave and currents from west to east, forming the subaqueous barriers. The sandy barriers gradually became higher and wider, and emerged from the water by which lagooas were insolated from the lake. At the same time9owing to strong evaporation9the lake began to shrink and its ecological envivonments to get deteriorated.

Abstract:The Nanran Lake is located in a closed basin at Manchou, Pintonv southern Taiwan. Soil in this area is the pleistocene red loam, a product of severe weathering. Clay is the major component in the soil. Most of the low valence elements have been leached out during weathering, resulting in very low pH values (pH 3.63-5-30). The infiltration water collected is about 5.00 in pH. Very little alkalinity in the lake waters is supplied from land. Chlorophyll a concentrations in the lake are mostly above 10 μg/L and suggest eutrophication. Most alkalinity concentrations are below 0.2 m mol(+)/L and the waters are sensitive or very sensitive to acid precipitation. Most phosphorus concentrations are higher than 20 μg/L, also indicating eutrophication. Low N/P reveal that nitrogen is the major limiting factor to the phytoplankton growth. The major element concentrations in the lake are controlled by the land and by the sea salt spray. In order to understand the major factors affecting the compositions of the lake water, rain water, infiltration water and lake waters were collected and analyzed for evaluation the ion contents and their relative ratios. Outflow from the lake was also measured, and the related meteorological data collected. The ion budget of the lake was established using the above data. Input from the rain was estimated to be 167×10³ equivalents, only about 6 percent of the total input to the lake. The other 94 percent are from the land. About 577×10³ equivalents, or 19 percent of the total input, is lost from the lake in the outflowing water. The rest accumulates in the lake and affects the composition of the lake water. Assuming that the excess ²¹⁰Pb is diluted by the organic matter in the water column, the authors estimated the accumulation rate of the organic matter between 33.7-52.9mg/cm²·a and that of the bulk sediments 581-911mg/cm²·a.

Abstract:Chitin is the second most abundant polysaccharide in nature. It has been estimated that 10u tons of chitin are produced annually in the aquatic biosphere in such forms as the exoskeletons of crustanceans, mollusca, coelenterates, in protozoa and in the cell walls of fungi and algae. Therefore the decomposition of chitin is an important component in the recycling of carbon and nitrogen in aquatic ecosystems. In the nature, conversion of chitin to β-1,4 N-acetylglucosamine(NAG) depends on microorganisms. In the present work, the dynamics and distribution of population, the species composition and the decomposing activity of chitin-decomposing microorganism in Donghu Lake (a eutrophic shallow lake in Wuhan, China) were studied. 1. Dynamics and distribution:During March-May, 1991, the numbers of chitin-decomposing microorganisms are higher in the Station I than in the Station I;and much higher in the sediment than in the water column (about 10²-10³). As the temperature increased from 9℃ to 25℃, the chitin-decomposing microorganisms increased with a higher ratio of actinomycetes. (Tab. l, Fig. 1). 2. Spesies composition Actinomycetes and bacteria are included in chitin-decomposing microorganisms. In 155 identified strains of microorganisms there are Streptomyces (72 strains), Streptosporangium (9 strains), Micromonospora (10 strains). Micropolyspora (11 strains), Bacillus (20 strains), (Serreatia (10 strains), Micrococcus (11 strains Aeromonas (11 strains), Brevibacterium (1 strain) and 2 strains unidentified. The Streptomyces and Bacillus are the dominant groups (45.9% and 12.7% respectively). 3. Comparison of decomposing activity of strains; Acording to the value of decomposing clear zone to colony size, the results are shown in Table 2. Worth mentioning is that there are about 55% strains which belong to actinomycetes with higher decomposing activity for chitin, the CZ/CS value over 2.

Abstract:An experiment of the pearl culture was made in the low dike retaining waters and eco-logic eliminating snail (Oncomelania) of the lake beach of Dongtin Lake. The result shows that the waters are of favourable conditions for the pearl culture. During the dropping in water level and the drying of the lake beach in winter and spring, the low dike can maintain a depth of above 50cm of water. Mortalities of living snail (Oncomelania) and snail egg may reach up to 100%. Under natural conditions, the plankton in the water body of the pearl culture amounts to 30000 indivduals/L; dissolved oxygen 9.54-9.74mg/L, Ca²⁺. concentration 44.9±0.06 mg/L;pH value 6.9±0.13, H₂S and CH₄ 0 value in the water body of the pearl culture when water temperature is at 20℃. These states of the water chemistry and biology are suitable for the requirement of the mussel (Hyriopsis cumingii) growth. Production rate of the pearl of excellent quality may reach to 41.3%, being 13.5%, 15.9% and 23.4% higher than that of the inland lake (27.8%), mute river (25.4%) and pond (17.9%) respectively.

Abstract:West Lake in Hangzhou is a small shallow lake. Its surficial sedimentary stratum is composed of algae faulschlamm layer and peat layer, and is mainly characterized by high organic carbon content and extreme high nitrogen contents but by relatively low degree of phosphorus enrichment. A simulation study in laboratory and on the spot was conducted to determine the effects of various environmental parameters on the phosphorus release rate and the capacity from the sediments of West Lake in Hangzhou. Factors investigated in laboratory included pH, temperaturetdissolved oxygen, redox potential and overlying water type. The lowest release capacity was found when the pH was at the range of 6.5-7.0 for the overlying water. Raising the temperature or lowering oxygen concentrations in the overlying water may also accederate phosphorus release. The highest release capacity was found to be about 0.368 μg P/g in laboratory. The average release rate measured on the spot in summer was 1.02 mg P/m²·d. The calculated release capacity from the sediments of West Lake was 1.346tP/a, equivalent to 36.4% of the average annual external phosphorus loading. The internal loading is a major contributory factor in the continuing eutrophic states of the lake.

Abstract:The history of mire research in China has lasted more than thirty years. A great deal of achievements have been obtained through the investigations in main distributed areas of mire during recent years. Importance should be attached to the following works:(1) Seting up a mire classification and information system; (2) Enhancing the basic theoretical research of mire progressively to perfect Chinars mire scienes; (3)Studying a method of exploitation and utilization of mire; (4) Establishing some mire ecological stations to protect some valuable mire resources.

Abstract:The water bodies acidification of different type of water bodies caused by acid rain and the buffer capacity are introduced and the effects of acid rain on some organisms at various trophic levels in aquatic ecosystem are reviewed. The sensitivity differences to low pH among some aquatic organisms and different developmental stages are summarized. Also, the tolerance variation of organisms to low pH owing to heredity and adaptability is described. The key characteristics of aquatic communities in acidified water are decreased species number9reduced diversity, lessened biomass and destroyed food chain. The toxic effect of low pH on aquatic life include inhibition of gas exchange, disorder of body salt adjustment, imbalance of acidity and alkalinity, and the combined effects with metals. Several problems are briefly discussed and some sugestions are put forward.

Abstract:Based on the model established, the author puts forward some indexes to describe fish population dynamics and characteristics.