Abstract:The present study aimed to evaluate the contribution of stress factors to the decline of Microcystis bloom, also tried to develop some indicator of decline. Four stress conditions including nitrogen starvation, phophorus starvation, dark and low temperature (10℃ ) were designed. Decrease of biomass and the concomitant change of antioxidant system, including superoxide dismutase (SOD) and catalase (CAT) activities were detected. The result indicated that growth was significantly inhibited under dark and low temperature. Microcystis population declined after 25 days under dark, while declined after only 7 days under low temperature. Compared with the physical stress, nutrition such as nitrogen and phosphorus did not limit the growth effectively in the early stage. Chlorophyll-a decreased as soon as being incubated into nitrogen free BG-11 medium. After being kept in phosphorus free medium for 20 days, chlorophyll-a reached peak, about the twice of the initial concentration, and then decreased at a rate of 0.1mg/(L·d), which was the highest decaying rate among the four factors. It indicated its significance of available phosphorus for Microcystis survival and decline. According to the results, when phosphorus was limited, or water temperature was decreased to 10℃ , cautions should be taken into account for the decrease of dissolved oxygen and possible increase of toxins or odors substances from the declining bloom. In healthy Microcystis, SOD activity was about 0.06U/mg protein, while CAT activity was too low to be measured. In addition, SOD activity increased earlier than CAT activity when Microcystis was exposed to stress conditions. CAT activity increased only when the content of chlorophyll-a began to decline. Both of the increase of SOD and CAT activities correlated negatively with the decrease of the content of chlorophyll-a though there were some exceptions. Combination of the two parameters would be potential indicator of bloom decline.

Abstract:The correlation between chlorophyll-a concentration and some environmental factors (water temperature, pH, DO, COD_Mn, TN and TP) in sixty shallow lakes in plain river network areas of Suzhou was studied by regression statistical method, and the spatial and temporal distribution characteristics of chlorophyll-a were also analyzed. The results indicated that there were some differences in the spatial and temporal distribution of chlorophyll-a in shallow lakes. In winter, the average concentration of chlorophyll-a was lower than that in summer. The temporal distribution of chlorophyll-a in winter and summer also had some similar pattern decreasing from east to west. Significantly positive correlations were found between chlorophyll-a concentration and water temperature, pH, dissolved oxygen, permanganate indexes. Water temperature was possibly the main limited factor of phytoplankton growth. At the same time, significantly positive correlation was found between chlorophyll-a and nitrite nitrogen, but not for ammonia nitrogen, nitrate nitrogen, total nitrogen. However, positive logarithmic correlation was found between chlorophyll-a and total phosphorus, and negative logarithmic correlation was found between chlorophyll-a and the ratio of total nitrogen to total phosphorus. The results suggestted that phosphorus might be the limited factot in the shallow lakes to some extent.

Abstract:Concentrations and distributions of various mercury (Hg) species, including total Hg (HgT), dissolved Hg (HgD), reactive Hg (HgR), particulate Hg (HgP), total methylmercury (MeHgT), dissolved methylmercury (MeHgD), and particulate methylmercury (MeHgP) in surface water and porewater of the sediment collected from Lake Caohai during the flood and dry seasons were analyzed by using CVAFS and GC techniques. The concentrations of HgT ranged from 1.7 to 9.0ng/L, HgR from 0.06 to 1.4ng/L, and MeHgT from 0.11 to 0.67ng/L in surface water, respectively. In the sediment porewater, the concentrations of HgD varied from 8.6 to 39.6ng/L, and MeHgD ranged from 0.11 to 4.9ng/L. The Hg species in surface water was mostly dominated with dissolved forms with an average of 87% of HgT in dry flow period and 51% of HgT in flood flow period, respectively. The HgD and HgP forms were significantly correlated with HgT. The MeHgD were positively correlated to MeHgT, showing that distributions of MeHgT were controlled by MeHgD. Concentrations of HgD and MeHgD in porewater were higher than that obtained in the underlying water, which suggestted that the sediment was a dominant Hg source to the lake.

Abstract:The stable nitrogen isotopic ratios of particulate organic matter (δ¹⁵N_POM) was used to elucidate the seasonal variation and vertical characteristics of the different dissolved inorganic nitrogen sources and autochthonous biogeochemistry processes in two lakes (Hongfeng and Baihua) in Guizhou Province, China. The δ¹⁵N values of surface POM seasonally varied from 3.7‰ to 14.9‰ in Lake Hongfeng and from 1.3‰ to 8.7‰ in Lake Baihua. It indicated that source of POM was greatly varied in these two lakes during study period. In Lake Hongfeng, the higher δ¹⁵N POM values appeared in winter (February, 2004) and summer (September, 2003). The highest δ¹⁵N POM values in winter were attributted to the input of high contents and 15N-enriched inorganic nitrogen from industry wastes. During spring, the δ¹⁵N POM values decreased when phytoplankton uptake ¹⁴ -enriched inorganic nitrate generated by nitrification in the interior Lake Hongfeng. The variation of δ¹⁵N values in surface POM coincided well with the variation of δ¹⁵N values of inorganic nitrogen sources. It suggestted that the variation of δ¹⁵N_POM mainly influenced by inorganic nitrogen sources, which might resulted from the impact of allochthonous human activities. In Lake Baihua, the higher values of δ¹⁵N_POM appeared in summer (September, 2003) while the values were low during winter season. These high and low values were possibly aroused by the growth of primary production and large 15N-depleted organic particles input from sewage respectively. In addition, the combination of δ¹⁵N_POM and C/N values in the vertical profile can be used to trace some special biogeochemistry processes in lacustrine ecosystem.

Abstract:The present distribution of organochlorine pesticides(OCPs) in surface sediments from Lake Taihu had been quantitatively analyzed by GC-ECD. OCPs were detected in all 20 samples, and total concentrations for 16 kinds of OCPs components ranged from 4.22 to 460.99ng/g(dw). Not only the northern part but also the center and the edge of the lake had higher concentrations, which was inconsistent with the distribution of organic carbons, nitrogen and phosphorus in surface sediments. DDTs, HCHs were the highest in all the detected compounds of OCPs in 20 samples. In DDTs, the residual level of p,p'-DDT was much higher than p,p'-DDE and p,p'-DDD, which showed there maybe new pollution sources recently. In HCHs, the contents of α-HCH and γ-HCH were similar, while β,δ-HCH had much higher residues caused by earlier use of this compound. The genoxicity of the typical locations were examined by the Ames test, and the genotoxic results were combined with the chemical analysis to determine the most responsible stressers for genotoxicity in the surface sediments of Lake Taihu.

Abstract:The distribution characteristic and correlation of AVS and SEM were studied in 28 surface sediments of whole Lake Taihu. The results showed that the concentration of AVS varied greatly in space (COV up to 100.77%), and high concentration of AVS were recorded in estuary of lake. Combined with the distribution characteristic of AVS, deposition rate and load of SO₄^2- probably caused the spatial difference of AVS. The high concentration of SEM was recorded in the area of estuary, and the concentration of SEM in northern part of Lake Taihu was higher than in the southern part. Three models including SEM/AVS, SEM-AVS and SEM-AVS/fOC (Toxicity was predicated when SEM/AVS>9 or SEM-AVS>2 or SEM-AVS/fOC >150μmol/g(OC)) were used to assess the sediment quality of Lake Taihu, and results showed that only site 0^# and 6^# exceeded the threshold of one and two of the three models. Overall, the surface sediments of Lake Taihu could not cause toxicity to benthic organism except site 0^# and 6^#.

Abstract:The chemistry of major cations (Mg²⁺, Ca²⁺, Na⁺and K⁺) and anions (HCO₃^-, SO₄^2- and Cl^-) in the water of Lake Pumayum Co and of its inflow river were studied, and the results revealed the obvious ionic difference among various inflow rivers and the lake.The chemical type of the lake water was Mg²⁺-Ca²⁺-HCO₃^--SO₄^2-, and the major ions of the main inflow river were Ca²⁺-Mg²⁺-HCO₃^-. In the lake inlet within the depth less than 2m of Jiaqu River, the main inflow river, there was significant variance of water chemistry. However, it was almost same at other area of the lake. Jiaqu River had a distinct effect on the chemistry of the water on the estuary delta, whereas other rivers have minor effect on the water on estuary. The Gibbs plot revealed that chemical compositions of the lake water was correlative with rock weathering in the drainage area. Ion ratio and ternary plots further explored the main processes controlling the water chemistry of the catchment were carbonate weathering, pyrite weathering and silicate weathering. The different water chemical characteristics between river water and lake water may result from the CaCO₃ precipitation. The outcome will benefit comprehending the environmental significance of carbonate in lacustrine sediment.

Abstract:According to the analysis of the grain size, content of heavy metals (Cu, Cr, Zn, As and Pb) and ¹³⁷Cs dating in Shilianghe Reservoir, the sedimentary rate and pollution characteristic of heavy metals were investigated. The geo-accumulation index was used to assess the pollution degree of heavy metals. It showed that the averaged sedimentary rate was 3.85cm/a, and Cu, Cr and Zn were in the light polluted level with the geo-accumulation index less than 1 during the past 40 years. The geo-accumulation index of As fluctuated strongly, but now it was in the light polluted level. The geo-accumulation index of Pb was more than 1, and the pollution level increased gradually from the bottom of the core and trends to aggravate.

Abstract:Lake Kusai lies in the Hoh Xil area, northern Tibetan Plateau. Based on the analyses of Total Organic Carbon content (TOC), Total Nitrogen content (TN) and Grain Size of sediments from Core KS-2006, this paper mainly analyzed the moisture variability in this area during the past 4000 years. The results showed that the moisture evolution of this area in the past 4000 years experienced the stages as follow: dry periods: 3900-3590 cal aBP, 3320-2630cal aBP, 1720-1420cal aBP and 1100-840cal aBP; humid periods: 3590-3320cal aBP, 2630-1720cal aBP, 1420-1100cal aBP and after 840cal aBP. Our results were generally consistent with the climatic changes inferred from the Oxygen Isotope, Dongge Cave, which indicates that the climate in northern Tibetan Plateau was also controlled by the Asian Monsoon. Additionally, Medieval Warm Period and Little Ice Age were well recorded in Lake Kusai as well.

Abstract:Lakes developed widely during Cenozoic era in central Tibetan Plateau. Researches on those lacustrine dolomite formed in that period is highly significaive to analyze the evolutionary process of Tibetan Plateau environment from then on. XRD, SEM and thin section analytical approaches were applied to analyze the relationship among Degree Order, crystal shape and the CaCO3 molal fraction of the dolomite samples took from Tuotuohe area. Based on the mineralogy and petrology features, investigation depends on the field work on the outcrops, and the origin mode of dolomite are diagnosed. Furthermore, the environmental changes recorded within the sedimentary sections are interpreted in connection with some tectonic movements which led environmental changes internal or external the Plateau.

Abstract:Based on the goal of water diversion for shallow lakes, taking the requirement of ecological hydraulics and economic factor into consideration, an attempt to establish an assessing indicator system for water diversion scheme of shallow lakes is put forward in this paper. The indicators are consisted of lake quality-improving indicators, hydraulic indicators and economic indicator. By the case of Lake Xuanwu, a 2-D water-quality model is adopted to simulate different schemes of water diversion for Lake Xuanwu with different flow flux, diversion mode, flow distribution of inlets, and flow distribution of outlets. Detailed assessing indicators of statistic results are obtained, and then the optimum water diversion scheme is assessed. The method can be applied to the assessment of water diversion on similar shallow lakes.

Abstract:A two-dimensional, laterally averaged Model CE-QUAL-W2 was applied to the Shanzai Reservoir to simulate the hydrodynamics and water quality in the water column. The modeling effort was supported with data collected by fieldwork and experiments within half a year. Furthermore, the study made a water quality assessment of the eutrophication in the outlet of reservoir from Apr. 7th, 2006 to Jun 7th, 2006, using Trophic State Indexes (TSI) method and analytical hierarchy process(AHP). The result showed that, On May 12th, TSI was higher than the other days, almost reached 80; and the first big water blooms lasted from Apr. 29th to the beginning of June, 2006. The modeling result of three scenarios (keeping original flux, decreasing water level and increasing flux) indicated that decreasing water level and increasing flux could greatly improve the water quality of outlet．

Abstract:The project of Water Diversion from Yangtze River to Lake Taihu has played an important role in preventing flood, and brings about great integrated benefits on society, economy and environment in the Taihu Basin since 2002. The paper discusses the methodology for evaluating the integrated benefit of Water Diversion, and uses analytical hierarchy process and weighted synthetic index to determine the integrated benefits of the project. Moreover, the paper uses market pricing method to determine the direct benefit of saving chemicals in the water works within the region. The value of synthetic index of integrated benefit is U=77, that means the project has large benefits to economy, society and environment of Yang-Cheng-Dian-Mao District, especially the water quality and quantity of rivers in the Taihu Basin has improved to meet water source quality, reducing health risk, promoting integrated utilization of water resource, improving living environment, expanding aquiculture benefit, saving water works expenditure, gaining industry water supply and agriculture benefits, etc. During 2002-2005, the four year benefit from improving drinking water quality by the project was 9.9 million, 29.2 million, 36.2 million, 35.1 million respectively, and totally 110.4 million. According to the proportion of economic benefit with integrated benefit, the imputed economic benefit was about 4.8 billion; consequently the integrated benefit was about 5.3 billion.

Abstract:This study presents a GIS/Remote sensing-aided procedure to monitor urban lake area change in Wuhan city, which grew rapidly in the 1990s. Four time-series Landsat images, the year of 1991, 1995, 2000 and 2002, were used here. Lake's border maps were made by NDWI(Normalized Difference Water Index) index and IILI(index of lake loss intensity) of 27 lakes were calculated for analysis. The results showed that the total areas of lakes in the urban area decreased up to 38.67km2 from 1991 to 2002. The temporal and spatial distribution of lake loss was affected by several factors such as city construction, transportation construction, policy guide etc. The urban lake can be well protected after changing into lake park. The present study suggested that legislation and lake planning were two approaches for urban lake protection.

Abstract:In order to solve the problem of suspended sediment influencing water depth measurements by remote sensing technology, the remote sensing sediment parameter was constructed by experimental methods and introduced into the research of water depth retrieval methods to weaken the effect of suspended sediment to remote sensing bathymetry. The study area is the South Channel to the South Passage in the Yangtze River Estuary. Results showed that: 1) the exponential models can estimate the water depth of less than 2m well, and the logarithm models can retrieve water depths from 2m to 7m accurately and the quadratic regression models can calculate the water depths from 7m to 14m better in the single factor nonlinear inversion models of water depth; 2) the multiple factor water depth inversion model of BP artificial neural network (BPANN) integrate water depth information of multiple wavelengths, and it performs the stronger capability to retrieve the water depths than single factor nonlinear models; 3)remote sensing sediment parameter constructed by experimental methods integrate suspended sediment information of multiple wavelengths, and weakens the effect of chlorophyll and environmental factors, and it can characterize the variations of suspended sediment concentration (SSC) better; 4) the sediment parameter water depth retrieval model of BP artificial neural network (SPBPANN) weakens the influence of SSC to remote sensing bathymetry, it performs the strongest capability than single factor nonlinear models and BPANN model.

Abstract:In order to investigate the level of genetic diversity of the endangered species Brasenia schreberi, three populations from Jiangsu and Zhejiang Provinces were sampled and analyzed using inter-simple sequence repeats (ISSR) markers. A total of fifty-four individuals were sampled. Twelve filtrated from 77 ISSR primers gave rise to 101 discernible DAN fragments of which 16 were polymorphic (15.84%). The average number of DNA bands amplified by each primer was 8.4. The Nei's genetic and Shannon's information indexes were 0.0395 and 0.0630 respectively at species level, 0.0391 and 0.0335 respectively at population level. Based on Nei's Gst value and Shannon's index, it showed that most of genetic diversity (85.79%) was within populations, and that gene flow (Nm) was 3.0199. It was concluded that vegetative propagation, habitat loss and fragment, introducing plants, and human disturbances may play a significant negative role on genetic diversity and genetic structure of Brasenia schreberi.

Abstract:Taking Stentor coeruleus for an instance, we have tested single cell PCR for single gene and whole genome. After optimization, we got perfect results. In the single cell PCR for single gene reaction, 40 fresh cells and 40 neutral red stained cells all got 100% success and rich products, and 40 cells kept in the alcohol (95%) for one week got 82.5% success. In the single cell PCR for whole genome reaction, we employed phi 29 DNA Polymerase and random primer for our PCR amplification and got rich products. Using whole genome amplification (10 times diluted) 4 gene loci were amplified, and all of them got objective gene section successfully.

Abstract:A total of 28 Bacillius strains isolated from Lake Dianchi were classified by amplified rDNA restriction analysis (ARDRA) on their 16SrDNA through restriction digestion by AluI. Our data showed that all strains isolated could be classified into 5 Operational Taxonomic Units (OUT), and OTU5 was the dominant one, including 14 species. The lytic effects of all strains on Microcystis aeruginosa and Anabaena flos-aquae were studied, and 6 strains in OTU5 showed much stronger activity than others. The supernatant of 4 strains in OTU5 exhibited lytic function at almost the same strong level as their corresponding whole broth, which indicated that extracellular lytic substance produced by Bacillus cells could have lytic effects on algae.

Abstract:The spatial distribution, temporal changes of water transparency and their influencing factors in Lake Fuxian, a deep lake in Yunnan Plateau, were analyzed according to the investigations during June-July in 2005 and the regular monitoring data since 1980. The Secchi disk transparency varied from 0.5-6.2m with an average value of 4.6m in Lake Fuxian during June-July in 2005, The spatial distribution pattern of transparency was: north area