Abstract:

Abstract:Nitrogen plays a key role in lake eutrophication.We collected several undisturbed sediment corevS from two lakes, Lake Hongfeng and Lake Baihua in Guizhou Province to analyze the concentration and profile distributions of total, exchangeable inorganic and fixed nitrogen.The result's show that: (1) the nitrogen loctcl in the sediments of the two lakewS is higher in comparison with the average of lakes and reservoirs in China.Their average concentration of total nitrogen ranges from 0.36% to 0.40% Cdry sediment weight).It is obviously due to influence of diagenesis on vertical profile of total nitrogen in the sediment.The sediment of the reservoirs may be one of main nitrogen sources to cause the eutrophication.(2) The concentrations of total nitrogen and the burial environmental conditions are two main factors in distribution of the exchangeable nitrogen on sediment cores.(3) The fixed nitrogen is one of major sinks of nitrogen in the two reservoirs sediments.The concentration of fixed nitrogen in Lake Hongfeng and Lake Baihua, 434.05 mg/kg and 416.94mg/kg respectively, is higher than the data reported for others lakes or reservoirs of China.

Abstract:Transportation and diffusion of nutrients and pollutants are one of the important procevS-ses in the large shallow Taihu Lake.They influence not only the distributon of water quality, but also the growth of phytoplankton and the algae bloom.Based on the results of a three-dimensional numerical simulation on the dynamicvS in Taihu Lake, China, a three-dimensional model of transportantion and diffusion of conservative substance has been built.The model has been calibrated by the total phosphorus changes from Jan.18 to Feb.22, 1997.The model results in winter are coincided with the observed.It describes that the model can be used to calculate the pollutants and nutrients transportation and diffusion without consideration of biochemical processes in winter in Lake Taihu, China.

Abstract:Taihu Basin water quality management decision support system (Taihu DSS) was developed for water quality management of river network in Taihu Basin.In the summer of 2000 algal blooms occured in Taihu Lake.Wangyu river was considered as the pilot river drawing water from the Yangtze River to Taihu Lake to solve the problem under emergancy time.So Taihu DSS was used to study the technique scenarios for drawing water from the Yangtze River to Taihu Lake through Wangyu river in different ways.To compare with the water quantity and water quality of Wangyu river entering Taihu Lake in different scenarios, the scenario that Wangyu river waster water was discharged through Li river gate into Grand Channel was adopted, which made Wangyu river drawing water from the Yangtze River to Taihu lake successfully in 2000, and deepened further research and the test.

Abstract:In 1990s, the flood disasters have frequently hitlen the Poyang Lake.The highest flood levels in 1990s as well as the mean water levels have exceeded the historical records.Ifs estimated that the highest flood leveLs have targeted a recurrence interval of 100 yearvS.The author suggested that at least three aspects might have impacts on the flood regimes in Poyang Lake in 1990s, i.e., temporal and spacial precipitation variations in the upper and middle reaches of the Yangtse River;alteration of the Yangtese River-Poyang Lake relationships;and direct recalmation in lakebeaches.

Abstract:Monitoring data in 2001 indicate that inner lake in Miyun Reservoir has reached eutrophication because of pollution of net-cage fishculture.The main water body of reservoir belongs to mesotrophication and tends to be eutrophication.The water body of inner lake exchange substance with main water body of reservoir through permeation and spread.When the water lever is over 150m, the waters between water bodies are linked together.Inner lake pollutes reservoir region seriously.Inner lake is a pollution source in Miyun Reservoir.For stabilizing water quality of Miyun Reservoir, it is necessary to stop activity of net-cage fishculture in inner lake.

Abstract:The L-arabinose resistance forward mutation test (ara test), together with Ames test, was performed for evaluation of mutagenicity of the surface water samples collected from Meiliang Bay, Taihu Lake in winter.The five of the nine surface water samples were detected as mutagen positive by ara test, most of them were collected from the estuary which flow into the lake or from the edge of shore area. The same tendency was observed with the involvement of mammalian S9 metabolic activation system.The roughly, coincident results were confirmed by Ames test when the sample doses applied were enhanced to two and a half times compared with that of ara test.The data suggest that detection sensitivity of ara lest is higher if intricate environmental samples are concerned.Thus, prospect for ara test to be the primary choice is prompted when the genotoxicity screening of environmental mixtures is required.

Abstract:The Release of phosphorus from sediments from the Hangzhou section of the Grand Canal and the effects of liming, ferric chloride addition, aeration and overlying water refreshment were studied in this paper.Two kinds of polluted sediments from the canal, one was sampled from sewage polluted section and the other sampled from the industrial wastewater polluted section of the canal, were used in the release experiment in the overlying water-sediment ratio of 1;5 (v/v).The results showed that, concentration of total phosphorus (TP) in overlying water was highest at the beginning of the release experiment with infrequently disturbed the overlying water, and decreased with the time of running.Release potential of the sediment sampled from the vSewage-polluled section was significantly higher than that of the sediment sampled from the industrial wastewater polluted section.Liming of overlying water resulted in the increase of TP concentration in overlying water, while ferric chloride addition and aeration lead to the decrease of TP concentration in overlying water.Overlying water refreshment also decreased the TP concentration in overlying water.However, all the above methods have not decreased the TP concentration in overlying water to 0.2 mg/L, which ivS the limitation value of the V catalog surface water., suggesting the release of phosphorus from the sediment of the canal could drastically affect the water quality.

Abstract:It was found that the concentration of Zn²⁺< at about 1.0μm0l/L was essential to keep optimal growth of Anabaena azotica Ley and also important to keep a quite high value of photosynthetic oxygen evolution rate, chlorophyll fluorescence (Fv/Fm) level and carbonic anhydrase activity, whereas the relative high concentration of Zn²⁺(≥5.Oμm) would inhibit the growth of A.azotica Ley, decrease its photosynthetic oxygen evolution rate, chlorophyll fluorescence and CA activity.The study of the absorption spectra of the phycobilisome-thy-lakoid membrane complex and the extraction of phycocyanin indicate that Zn²⁺ may affect the photosynthesis by its effect on the phycobilisome especially the phycocyanin.Since CA is a Zn²⁺-containing metalloenzyme and may provide a high concentration of CO₂ to Rubisco in the process of CO₂ fixation, it is suggested that Zn²⁺ may affect the photosynthesis by acting on CA.

Abstract:Potamogeton pectinatus L., with extensive adaptability, is a perennial submerged aquatic macrophyte.It can survive in hyer-eutrophic waters.The results show that net photosynthetic rate at 10℃ was 0.88mg/(g·h) and its optimum temperature was at 25℃.Poor growth was found at 30℃.In Dianchi Lake, the maximal net photosynthetic rate fell in January to March and minimal value occurred in June.This species can regulate content of chlorophyll a and b to use light better.The light compensation point in P.pectinatus 358 to 1256Lx, depends on temperature.

Abstract:According to the study of the pimary production and light in Meiliang Bay Taihu Lake in May, October, December of 1998, August of 1999 and July, September of 2001, the anthorvS found thal the greatest primary production was at the depth of 0.2cm, the relationship between primary production(P) and the concentration of Chla was;p=0.012~0.028 [Chla] (n=30).On the basis of the relationship between light spectrum and concentration of Chla, as well as the relationship between primary production and light intensity, the relationship between primary production and light spectrum was found and validated.Further analysis revealed that the K_d of light spectrum at the blue end and at the red end was greater than that of green, the lowest was at 550 nm.

Abstract:This paper studied the plankton community of fish and shrimp culture ponds in saline-alkaline wetlands during May to vSeptember 1997.In terms of numbers, the species of Chloro-phyta dominated the community of phytoplankton in May, June and August, and Cyanophyta were the main taxa in July and September.However, Cryptophyta, Euglenophyta and Ba-cillariophyta were the most important components of the phytoplankton community in terms of biomass.According to the analysis of biomass, Copepoda was predominant in May and June, and Rotifera and Protozoa dominated the zooplankton community in July and August, respectively.Our results also suggests that the changes in the plankton communities of the ponds in saline-alkaline wetlands are due to a number of factors including nutrient concentration, abundance of fish and shrimp and water temperature.

Abstract:The production of Alocinma Longicoryjis in Lake Houhu was estimated by two method.Tlie results are: 2.22 g/(m²·a) of wet weight with shell or 0.111 g/(m²·a) of dry weight shell-free by size-frequency method;2.177 g/m².a of wet weight with shell or 0.109 g/m²·a of dry weight shell-free by instantaneous growth method.The corresponding P/B ratio are 4.0,5.4,respectively.

Abstract:The artificial enhancement technique of freshwater shrimp Macrobrachium nipponensis, in inland waters was studied in 2000~2001, It could be concluded that to select the egg-carrying shrimps whose embryos arc brown or analogous brown to hatching in net-cages, and distributed evenly in the whole water, and then release directly the larvae into the whole water is an effective method.Through this method, the output of Macrobrachium nipponensis in Lake Wanghu situated in county Yangxin of Hubei Province has been increased obviously from 10000 kg, before artificial enahneement (in 2000), to 35000kg,after artificial enahneement (in 2001).The numbers (N,kg) of egg-carrying shrimps which are hatched in nct-cages could be calculated according to the formula: N≥2Y·(1000·R·W)^-1,where R means the general recapture rate (normally, W(g/ind) meanvs mean body weight, and Y Ckg) means plan yield, seperately.

Abstract:This paper introduces the structure of network lake database, the Web-based integrate database of TaiHu basin is taken as an example to illustrate that how to set up a network database by using WWW,commericial WebGIS software, spacital database engine and client/server technology.Lake information of Lake Taihu and Taihu basin is issued accross the internet,so that each user all over the world can view,query and download the desired datafiles.More than that, the GIS data sharing and maintaining will come true in Lake Taihu Database Website.