Abstract:Atmospheric concentrations and deposition fluxes of particle-associated polycyclic aromatic hydrocarbons (PAHs) were measured over a 1-year period (2001-2002) at a small urban lake, Lake Luhu, in Guangzhou, aiming to estimate their atmospheric loadings to the lake. The annual average PAH deposition fluxes was 0.47mg/(m²·a). It was estimated that within a whole year there was approximately 0.1kg of particle-associated PAHs depositing to the lake from atmosphere. Significant seasonal variations of the PAHs deposition fluxes were observed, suggesting that both highly variable atmospheric PAHs concentrations and complex scavenging processes controlled the result. In the whole year, the highest particle deposition fluxes of PAHs were observed in winter and spring and the lowest fluxes were in autumn. Compared the compositions of deposition fluxes of particle-associated PAHs to that of total suspended particle (TSP) in the air, wet deposition contributed the heavyweight PAHs to deposition fluxes, whilst dry deposition along with low temperature would favour the deposition of lightweight PAHs. With the increasing rainfall, the composition of particle-associated PAHs deposit to the urban lake became similar to that of the total suspended particulates (TSP).

Abstract:The core sample was collected in Chaohu Lake in December 2001. The sediment layers were dated by ²¹⁰Pb. The results show that the sediment core represents 110 years of depositional time. Organic compounds were extracted from sediments using Soxhlet extraction by dichloromethane and methane. The n-alkanes were analyzed by chromatography/mass spectrometry. Distribution patterns of n-alkanes were presented. The sources of n-alkanes were discussed. The results show that from the depth 21 to 25cm and 16 to 20cm n-alkanes was attributed to the mixture of terrestrial plants and aquatic algae; from the depth 11 to 15cm, with sedimentary time of 1952-1967, the sample was contaminated by petroleum hydrocarbon; from the depth 10cm to surface, the source of algae and bacterium dominated n-alkanes, especially the top 5cm sample with high concentration of n-alkanes and TOC, which meant that the nutrient level especially eutrophication was increased in Caohu lake during this stage.

Abstract:At present, with digital terrain analysis technologies, calculating topographic information directly, modeling hydrological process and extracting hydrological data automatically from digital elevation models (DEM) is the focus of digital hydrology, and the present Geographic Information System (GIS) software based on raster data structure provide solid foundation for the modeling hydrological process, too. Automated extraction of drainage features from DEM is a very important research item of them, and has been widely used in actual works. The paper discussed the principles, methods and process of automated extraction of natural stream networks of watershed from DEM. The upper reaches watershed of Xitiaoxi as a case of study, a raster DEM is used to define surface drainage and extract the stream networks. Through comparing the stream networks delineated from DEM with the actual stream networks, it can be conclude that in the mountains area, especially the area of mean slope no less than 3 degrees, the delineated stream networks would be reliable. In the flat region of mean slope less than 3 degrees, the delineated stream is much different from the actual stream networks. In order to solve the problem, we put forward the restricted river channel method by digitizing the trunk streams and the flat land rivers. With the method, we got the delineated steam networks same as the actual stream networks, and make the simulation of hydrologic factor has more practical value. The method has universal reference value for hydrological modeling of other watersheds, and can improve the efficiency of hydrological modeling obviously.

Abstract:Concentrations of metals, organic carbon (OC), total nitrogen (N), total phosphorus(P) and forms of phosphorus as well as activities of ²¹⁰Pb and particle size were determined on two cores from northern Taihu Lake, China. The sediments are dominated by silts and clayey silts, which become finer upward. Results of ²¹⁰Pb analysis indicate strong disturbance and erosion at the sampling sites. Concentrations of metals are:Cu, 15.8-35.6 mg/kg;Zn, 61.0-136.4 mg/kg;Ni, 26.6-46.2 mg/kg;Li, 36.7-69.0 mg/kg;V, 88.3-142.0 mg/kg;Ti, 3929.2-5508.9 mg/kg; Mn, 840.9-2369.8 mg/kg;Fe, 2.88-6.24 %;Al, 5.17-10.13 %. Levels of Cu, Zn, Ni, Li, V, Fe and Al show significant positive relationships with the fraction of clay and their down-core variations are therefore caused mainly by particle size. When compared to the mean contents of shale, these metals show no significant anthropogenic pollution. The ratio of OC to N (C/N) range from 9 to 20, suggesting a dominance of detrital input of organic matter. The dominant pool of phosphorus is the detrital form. In both cores, organic phosphorus increases toward the surface layer, implying either higher organic phosphorus input in recent years or its better preservation.

Abstract:Cumulated sediments during marsh wetlands development really recorded the region environment change and marsh processes. Here we reported a case study on the Xianghai marsh wetlands at downstream of an anourous river-Huolin River, Jilin Province. By analysis of sediment layer structure, sediment bulk density, and sedimentation rate in the typical sedimentation profiles, the following results are revealed:The layer relationship among marsh sediments could reveal the marsh formation and its environment change; The riverine marsh might receive much more mineral sediments; the mark of river shifting near 1880-1885AD in the research field was discovered; That the sedimentation rates of Xianghai marsh wetlands were similar to typical estuarine deltas indicated the property of trailing end of estuarine; The cause of suddenly accelerating of the sedimentation rates in Xianghai marsh wetlands in recent 50 years, might related with the human activities strengthen, the plants destroy, and top soil strictly lose after liberation. Furthermore, on time scale, the suddenly accelerating of the sedimentation rates had much better coupling with the mining period of time of large open-cast coal located on upstream of the Huolin River catchments.

Abstract:By studying on Pingwang water level and Mishidu tide level Hydrograph in Taihu Basin and their impacting factors, the concepts, ranges, moving and the decomposition as well as the reconstruction of the averaged tide level hydrograph are put forward. With the method of the statistics correlation, the forecasting models of the Pingwang water level and Mishidu tide level hydrograph are developed. Using the measuring data in flood season from 1996 to 1999, the forecasting model are calibrated, and the results of the calibrating are satisfactory. The methods proposed in this paper are useful to the flood forecasting and controlling in Taihu basin.

Abstract:Abstract This paper focuses the quantitative evaluation of non point sources of pollution by graphical maps of watershed and estimating area based load of pollutants of various land uses with the use of Arc/View Geographic Information System. The representative study is carried out in the Xinshan sub-watershed of Taihu watershed. It involves the simulation of pollutants load by watershed; watershed area and event mean concentration (EMC) by pollutants. Further the NPSP evaluation is carried out with the provision of Best Management Practice (BMP's) scenario in the watershed. BMP's utilization practice has provided the most efficient, practical and cost effective steps for the reduction of NPSP in the watershed. Using watershed boundary and land use data, nutrient EMC, and point Load, NPSP is evaluated based on PLOAD GIS model extension of Watershed 3.0. Model simulation is evaluated using tabular and graphical analysis. Support for this work is provided in the part by funding from the Natural Science Foundation in China for the project No. 50239030

Abstract:Lake Donghu(Wuhan), a subtropical shallow lake near the Yangze River, is polluted heavily by some sewage inputs. Based on total phosphorus (TP) and chlorophyll-a, Station I is defined as a hypertrophic lake, and Station Ⅱ is defined as a eutrophic lake, and Station Ⅲ is defined as mesotrophic lake. The main purposes of this paper are to describe the vertical distribution of acid -volatile sulfide (AVS) in the sediments of three stations with different trophic levels in Lake Donghu, and to discuss the possible mechanisms underlining these patterns with emphasis on the possible effects of organic matter. The results indicate that AVS peak appeared in anoxic sediments in all three stations. Two patterns of AVS distribution were found. The AVS profiles in cores of Station I and Ⅱ showed a maximum concentration at about 5-cm depth, and then a drop-down at a lower level. On the contrary, the AVS profile in the cores of Station Ⅲ showed AVS peak between 10 cm to 20 cm depths. There was closer relationship between OM and AVS in the sediment with high concentration of OM than with low concentration of OM, and AVS/OM ratio was in the order of Station I > Ⅱ > Ⅲ. This indicates that organic matter exerted great effects on the distribution of AVS in the sediment. The content of AVS in sediments is mainly affected by decompose of organic matter, deposition, dissolution and oxidation of AVS. High organic matter flux shifted AVS peak into the surface sediment, and narrowed the depth interval over which the accumulation of AVS became maximized at the more eutrophic Stations I and Ⅱ. The convection-diffusion model of AVS reported by Fang et al was tested. The vertical distribution of AVS accorded with the model better in eutrophic lake with high concentration of OM than with low concentration of OM.

Abstract:Heavy metal concentrations (As, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn) of superficial sediments in the Nansihu Lake were investigated in April, 2002. The determination of the heavy metal distribution of the lake's superficial sediments was carried out by ICP-AES. The potential ecological risk index (RI) and geological acumination index(I_geo), as the quantitative diagnostic tools, were used to evaluate the pollution degree of various heavy metals in the sediments. The results show the distribution of pollutants in the sediments could be divided into three sections with different ecological risk characteristics:(1) light pollution area in Zhaoyang Lake, (2) medium pollution area in Dushan Lake, and ⑶ heavy pollution area in Nanyang Lake.

Abstract:The economy in Taihu Basin of Jiangsu Province is developing very quickly, which has led to large increase of water demand for urban and industry use. Overexploitation of underground water has given rise to serious land subsidence. At present, the area of land subsidence in Suzhou, Wuxi and Changzhou has reached 5000 km². Land subsidence has great influence on the security of water supply and has increased the expanse of flood mitigation. Closing the deep wells, adjusting industrial structure, quickening the development of regional water supply and strengthening comprehensive water management are important measures to control land subsidence.

Abstract:The effects of the release of phosphine on the growth of Microcrystis aeruginosa were experimentally studied. Using the method of Algal Growth Potential Test, the effects of phosphine and its oxidation products, such as phosphite and hypophosphite, on the growth of Microcystis aeruginosa, one of the dominant algae during water bloom seasons, were examined. The results showed that phosphine products had great influence on the growth of Microcystis aeruginosa. The release of phosphine from eutrophical waterbody perhaps may play an important role on the breakout of water bloom in lakes.

Abstract:The effects of CDOC on the attenuation of close ultraviolet and blue light in Chaohu Lake and Longgan Lake were studied. Results revealed that the difference of soluble TC in two lakes was not significant, but CTOC in Chaohu Lake was larger than that of Longgan Lake. The absorb curve of CDOC with different sources was similar except for difference in quantity. In Chaohu Lake, there could be observed a peak between 355-400nm on the attenuation curve and K_d was larger, while in Longgan Lake, the attenuation curve was increased with decreasing wavelengths under 500 nm. The best relationship between K_d and CDOC was at 355 nm as the result of co-effect of suspended solids, Chlorophyll and CDOC.

Abstract:This article computes the currencified cost of water environment changing in Taihu Basin during 1987-2001. The deteriorated water environment in Taihu Basin has led an environment cost up to about 125.1 billion yuan with a increase of 6.67% per year. The cost accounts for 19 percents of the GDP in south Jiangshu province in 2001. Moreover, this paper has checked the effect of environment protecting policy implementation by established the policy-driving model of environmental change in Taihu Basin. The outcome suggests that the corresponding environment policy is effective because the environment policy has dropped the cost by 61.79%. Finally, this article put forward some suggestion on improving environment quality from several aspects, i.e. adjusting the industry structure, developing circulation economy and establishing the environment finance system from several channels.

Abstract:In this paper, the wetland resources' features and functions of Honghu Lake are expounded from some aspects, such as geology, landform, meteorology, hydrology, soil, biodiversity and so on. Due to the wetland resources of Honghu Lake being threatened by floods and the human activities, some countermeasures of proper use and conservation of the wetland resources of Honghu Lake are proposed.

Abstract:Fuxian Lake is a deep lake with a capacity of 184×10⁸ m³. Based on the incessant monitoring statistics during 1980-2000, the water quality as well as the eutrophication status was revealed in Fuxian Lake,.i.e. the phytoplankton density increased 2.6 times, Chl.a 3 times while SD decreased~50%. Comprehensive assenssment of nutrient status and evolution during the past 20 years indicated that a sharp growth of TSI would bring out a potential possibility and danger of eutrophication which has compelled us to take some efficient, effective measures to protect the lake from further deterioration or invaluable lose both economically and ecologically in the future would be seen.