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Seasonal variation of potential denitrification rates of surface sediment from Meiliang Bay, Taihu Lake, china

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Journal of Environmental sciences 2010年第7期22卷 961-967页

作者： Jicheng Zhong, Chengxin Fan, Guofeng Liu, Lei Zhang, Jingge Shang, Xiaozhi GuState Key Laboratory of Lake Science and Environment, nanjing institute of {2. and {3., chinese Academy of sciences, nanjing 210008, china. [a] State Key Laboratory of Lake Science Environment Nanjing Institute of Geography limnology Chinese Academy of Sciences Nanjing 210008 China

The regulatory effects of environmental factors on denitrification were studied in the sediments of Meiliang Bay, Talhu Lake, in a monthly sampling campaign over a one-year period. Denitrification rates were measured in slurries of field samples and enrichment experiments using the acetylene inhibition technique. Sediment denitrification rates in inner bay and outer bay ranged from 2.8 to 51.5 nmol N2.（g dw （dry weight）·hr） and from 1.5 to 81.1 nmol N2.（g dw·hr）, respectively. Sediment denitrification rates were greatest in the spring and lowest in the summer and early autumn, due primarily to seasonal differences in nitrate concentration and water temperature. For each site, positive and linear relationships were regularly observed between denitrification rate and water column nitrate concentration. Of various environmental factors on denitrification that we assessed, nitrate was determined to be the key factor limiting denitrification rates in the sediments of Meiliang Bay. In addition, at the two sites denitrification rates were also regulated by temperature. The addition of organic substrates had no significant effect on denitrification rate, indicating that sediment denitrification was not limited by organic carbon availability in the sediments. Nitrate in the water column was depleted during summer and early autumn, and this suppressed effective removal of nitrogen from Taihu Lake by denitrification.

关键词： denitrification sediment environmental factors Taihu Lake

Nutrient fluxes induced by disturbance in Meiliang Bay of Lake Taihu

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Science china Earth sciences 2006年第z1期49卷 186-192页

作者： LUO Liancong, QIN Boqiang, ZHU Guangwei, SUN Xiaojing, HONG Dalin, GAO Yajun & XIE Rui nanjing institute of {2. & {3., chinese Academy of sciences, nanjing 210008, china nanjing Hydraulic Research institute, Ministry of Water Resources, nanjing 2.002., china 1. nanjing institute of {2. & {3. Chinese Academy of Sciences Nanjing 210008 China2. Nanjing Hydraulic Research Institute Ministry of Water Resources Nanjing 210024 China

A wave flume experiment was conducted to study nutrient fluxes at water-sediment interface of Meiliang Bay under different hydrodynamic conditions. The results reveal that hydrodynamics has remarkable effects on nutrient fluxes in this area. With a bottom wave stress of 0.019 N m-2.(equivalent to disturbance caused by wind SE 5-7 m s-1 at the sediment sample site of Meiliang Bay), the fluxes of TN, TDN and NH4+-N were separately 1.92. 10-3. -1.81 × 10-4 and 5.2.× 10-4 mg m-2.s-1(positive for upward and negative for downward), but for TP, TDP and SRP, the fluxes were 5.69 × 10-4, 1.68 × 10-4 and -1.2. × 10-4 mgm-2.s-1. In order to calculate the released amount of nutrients based on these results, statistic analysis on the long-term meteorological data was *** result shows that the maximum lasting time for wind SE 5-7 m s-1 in this area is about 15 h in summer. Further calculation shows that 111 t TN, 3.0}t NH4+-N, 3. t TP and 10 t TDP can be released into water (the sediment area was 47.45% of the whole surface area), resulting in concentration increase of 0.02., 0.007, 0.007 and 0.002.mg L-1 separately. With stronger disturbance (bottom wave stress is 0.2.7 N m-2.which is equivalent to disturbance caused by wind SE 10-11 m s-1 at the same site), there has been significant increase of nutrient fluxes (1.16× 10-2. 6.76×10-3. 1.14× 10-2.and 2.14× 10-3.mgm-2.s-1 for TN, DTN and NH4+-N and TP). The exceptions were TDP with flux having a decrease (measured to be 9.54× 10-5 mgm-2.s-1 ) and SRP with flux having a small increase (measured to be 5.42.× 10-5 mgm-2.s-1). The same statistic analysis on meteorological data reveal that the maximum lasting time for wind SE 10-11 m s-1 is no more than 5 h. Based on the nutrient fluxes and the wind lasting-time, similar calculations were also made suggesting that 2.2.t TN, 13..9 t TDN, 2.8 t NH4+-N, 42.7 t TP, 2.0 t TDP and 1.1 t SRP will be released from sediment at this hydrodynamic condition resulting in the concentration

关键词： hydrodynamics disturbance water-sediment interface nutrient release flux Lake Talhu.

Estimation on dynamic release of phosphorus from wind-induced suspended particulate matter in Lake Taihu

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Science china Earth sciences 2004年第8期47卷 710-719页

作者： FAN Chengxin1, ZHANG Lu1,2. QIN Boqiang1, WANG Sumin1, HU Weiping1 & ZHANG Chen1 1. Taihu Lake Laboratory for Ecosystem Research, nanjing institute of {2. & limnology, chinese Academy of sciences, nanjing 210008, china 2. Graduate School of chinese Academy of sciences, Beijing 10003., china 1. Taihu Lake Laboratory for Ecosystem Research Nanjing Institute of Geography & Limnology Chinese Academy of Sciences 210008 Nanjing China 2. Graduate School of chinese Academy of sciences 100039 Beijing China

Through man-made disturbance experiments, the corresponding relationships be-tween suspended particulate matter (SPM) and wind speed in different lake areas were simu-lated, the physicochemical formal transformation and biological mineralizing and decaying processes of phosphorus in SPM were studied, the contribution of phosphorus transformation to phosphorus loading of the water of Lake Taihu was quantitatively estimated. The results show that about 0.44 t·a-1 loading in Lake Taihu mainly comes from phosphorus-releasing action of SPM in physicochemical transformed to soluble reactive phosphorus (SRP), and the contribution mainly from biological mineralizing and decaying was about 42..8 t·a-1, which is equal to 15.0% of the total external loading of Lake Taihu, namely 4.7—7.5 times as much as SRP loading en-tering the lake by the rivers; thus it is the important source in dynamical internal loading of the lake. The determining factors for dynamical internal loading in lakes are organic phosphorus content in suspended solid and its biological transition availability.

关键词： phosphorus release,wind wave disturbance,particulate decaying,dynamical loading,Lake Taihu.

Dating sediments on several lakes inferred from radionuclide profiles

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Journal of Environmental sciences 1998年第1期10卷 58-65页

作者： Xiang Liang Lake Sediment and Environment Laboratory,nanjing institute of {2. & {3., chinese Academy of sciences,nanjing 210008,china

In this paper, several sediment cores from three lakes (Gucheng Lake, Dianchi Lake and Dabusopao Lake) in the different regions of china were dated radiometrically by 2.0 Pb, 13. Cs and in Dianchi also by 2.1 Am. The study shows that the profiles of 13. Cs in lake sediment of china generally have 2.4 distinct chronological markers, i.e. the onset of fallout in 1954 and peak fallout in 1963. 1974 and 1986. As many places of the northern hemisphere, the peak fallout in 1963.was the result of the atmospheric atomic weapons test. But in some areas of china, there may be have one or two other peaks of 13. Cs fallout, one can derive from Chernobyl fallout in 1986 and the other is caused by the nuclear testing fallout in early 1970s. So in these areas, the profiles of 13. Cs can have 2.or 3.peaks as the time markers. 2.1 Am, which is another fallout product from nuclear weapons testing, also provides a useful dating marker in Dianchi. These time markers are of considerable value to confirm 2.0 Pb dates in the three lakes. Despite there are some questions remain concerning the interpretation of these radionuclide records in lake sediments, coupling with 2.0 Pb and 13. Cs (and/or 2.1 Am) is suggested to be a valuable limnological tool for establishing sediment chronologies for the lake sediments in china.

关键词： lake sediment radionuclide dating method.

AN APPROACH ON SEVERAL PROBLEMS OF china'S URBANIZATION DEVELOPMENT

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Journal of Geographical sciences 1996年第2期6卷 35-41页

作者： Chen Wen(nanjing institute of {2. & {3., CAS, nanjing 210008People’s Republic of china) nanjing Inst of Geogr + limnology CAS Nanjing 210008 China

china, having urique national conditions, is facing a basic contradiction between large numbers of less educated surplus rural labor forces and limited capacities of urban employment and infrastructure on the urbanization ***, the urbanization model should prevail in comprehensive and several ways: (1)On occupational and spatial shift rural surplus labors, two fashions of 'leaving land bot not countryside' and 'leaving both land and countryside' should be integrated with joint effort of cities and countryside. (2. On urbanization motive, urban construction will be invested by not only the govermment (from the upper), but the locality, personnel and foreigners (from the lower). (3. On urban scales, metropolis,large, medium-sized and small cities and towns should play fully their roles to absorb rural surplus lanors. Thereby, the present urban development policy needs to be rectified, which this paper has discussed particularly. (4) On account of great regional disparities in china, urban development should perform different models in different regions. In addition, this paper has also focused on the problem and its primary countermeasures of 'labor force mass', a hot issue closely related to urbanization and rural labor transfer.

关键词： national conditions urban development model urban development policy,rural labor mass

The role of aerial algae in the formation of the landscape of the Yunnan Stone Forest,Yunnan Province, china

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Science china Earth sciences 2004年第9期47卷 846-864页

作者： TIAN Youping1,3. ZHANG Jie2. SONG Linhua1 & BAO Haosheng2.1. institute of Geographic {3. and Natural Resources Research, {2. Academy of {3., Beijing 100101, china 2. Department of geography, nanjing University, nanjing 2.0093. china 3. School of Earth {3. and Resources, china University of Geo{3., Beijing 100083. china institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Department of geography Nanjing University Nanjing 210093 China School of Earth sciences and Resources China University of Geosciences Beijing 100083 China

Aerial algae on the surface of carbonate rocks at the Stone Forest, Shilin County, Yunnan Province, china, and their bioerosion were investigated in the field and studied in the laboratory in detail. Through the observation, identification and statistics of more than one hun- dred algal samples and rock samples with the optical microscopes (stereomicroscope, biological microscope) and the scanning electronic microscope (SEM), the relationships between erosional forms on the surface of the Stone Forest and algae and/or algal communities and the genetic mechanism for the formation of erosional forms were analyzed. It is suggested that aerial algae play an active role in bioerosive processes that may affect the formation of karst erosional forms. These effects include both direct and indirect ones. The direct effect is the initiative control (algal shape-controlling role) of algae on the formation of karst forms of various scales, mostly mi- cro-scale (3.) and minor-scale (10-3.10-1m) erosional forms. The algal shape-controlling roles can be divided into the algal individual shape-controlling role and the algal community shape-controlling role. The former mostly controls the formation of micro-scale erosional forms, while the latter mostly controls the formation of micro-scale and smaller minor-scale erosional forms. The indirect effect refers to the promoting role of algae in the formation of karst forms, which may affect the formation of karst forms of all types and scales. The bioerosion of algae accelerates the weathering process of the whole Stone Forest karst landforms.

关键词： aerial algae, bioerosion, the Stone Forest, Yunnan Province, china.

Study on the simulation of transparency of Lake Taihu under different hydrodynamic conditions

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Science china Earth sciences 2006年第z1期49卷 162-175页

作者： PANG Yong, LI Yiping & LUO Liancong College of Environmental Science and Engineering, Hohai University, nanjing 2.0098, china nanjing institute of geography & limnology, chinese Academy of sciences, nanjing 2.0098, china Hohai Univ Coll Environm Sci & Engn Nanjing 210098 Peoples R China chinese Acad Sci Nanjing Inst Geog & Limnol Nanjing 210098 Peoples R China

It was indicated in this study that there were negative relations between the concentrations of suspended solid (SS) and transparency according to the analysis of measured data of Lake Taihu. Their relations in pervious studies were reviewed, which showed that the changes of transparency in Lake Taihu could be reflected by simulating suspended solid concentration (SSC). Measured data showed that the changes of SSC with wind speed were similar at different water *** increased with the increasing of wind speed. Both wave and lake current of Lake Taihu had positive relations with SSC. However, wave was the main factor affecting sediment suspension, while flow took the second place. In this study, a numerical model coupling lake current, wave and SSC of Lake Taihu was developed. In the SS model, the combined effects of wave and current were *** amounts of suspended and deposited sediments near the lake bed surface layer were treated separately. The stochastic characteristics of turbulent flow pulsation near lake beds were also considered, and the start-up conditions of sediment suspension were introduced to the model. The model elucidated the mutual exchange processes between sediment particles in SS and active sediments within and on the bed surface layer. Simulated results showed that lake current had relatively significant effects on the SSC at littoral areas of Lake Taihu, while SSC at the central area of the lake was mainly influenced by wave. The changes of transparency with SSC were simulated for Lake Taihu using this model. Calculated results were validated by measured data with good fitness, which indicated that the model is basically suitable for the simulation and prediction of transparency of Lake Taihu.

关键词： transparency suspended solid hydrodynamlc sediment suspension model.

Simulation　of　sludge－dredging　effects　in　controlling　nutrient　release　of　LakeKasumigaura　with　large－size　core　samples

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Journal of Environmental sciences 1996年第4期8卷 385-389页

作者： Fan Chengxin (nanjing institute of {2. and {3., chinese Academy of sciences,nanjing 210008,china) Morihiro AIZAKI Kunio KOHATA(The National institute for Environmental Studies, Tsukuba), Japan nanjing Inst. Geogr. and limnology Chinese Academy of Sciences Nanjing 210008 China Natl. Inst. for Environ. Studies Tsukuba Japan

Nutrient release from the dredged and undredged sediments in Lake Kasumigaura were simulated under the laboratory control conditions with large-size core samples. It was found that phosphate and ammonia release fluxes are less in aerobic than those in anaerobic. In different simulated dredged depth, the phosphate release showed large divergence in the anaerobic than in the aerobic. There was a larger accumulated release of phosphate and ammonia at actual dredged (St. B) than the undredged (St. A) in anaerobic condition. This showed that the sludge-dredging was effective of controlling phosphorus and nitrogen release. A preliminary assessment is drawn from the experiments that the sludge-dredging work in Tsuchiura Bay of Lake Kasumigaura can reduce about 15. 9% of phospbate and 56. 2. of anunonia release from the sediments respectively.

关键词： sludge-dredging nutrient release aerobic and anaerobic conditions core samples Lake Kasumigaura.

Preliminary study on assessment of nutrient transport in the Taihu Basin based on SWAT modeling

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Science china Earth sciences 2006年第z1期49卷 135-145页

作者： LAI Geying, YU Ge & GUI Feng nanjing institute of {2. & {3., chinese Academy of sciences, nanjing 210008, china The Graduate School of the chinese Academy of sciences, Beijing 10003., china Key Lab of Poyang Lake Ecological Environment and Resource Development, Jiangxi Normal University, Nanchang 3.002., china 1. nanjing institute of {2. & {3. Chinese Academy of Sciences Nanjing 210008 China2. The Graduate School of the Chinese Academy of Sciences Beijing 100039 China3. Key Lab of Poyang Lake Ecological Environment and Resource Development Jiangxi Normal University Nanchang 330027 China

With the Taihu Basin as a study area, using the spatially distributed and mechanism-based SWAT model, preliminary simulations of nutrient transport in the Taihu Basin during the period of 1995～2.02.has been carried out. The topography, soil, meteorology and land use with industrial point pollution discharge, the loss of agricultural fertilizers, urban sewerage, and livestock drainages were all considered in the boundary conditions of the simulations. The model was calibrated and validated against water quality monitoring data from 2.01 to 2.02. The results show that the annual total productions of nitrogen (TN) and phosphorus (TP) into Lake Taihu are 40000t and 2.00t respectively. Nutrient from the Huxi Region is a major resource for Lake Taihu. The non-point source (surface source) pollution is the main form of catchment sources of nutrients into Lake Taihu,occupied TN 53. and TP 56% respectively. TN and TP nutrients from industrial point pollution discharge are 3.% and 16%, and sewerage in both forms of point source and non-point source are TN 3.% and TP 47%. Both the loss of agricultural fertilizers and livestock drainages from the catchment should be paid more attention as an important nutrient source. The results also show that SWAT is an effective model for the simulation of temporally and spatially nutrient changes and for the assessment of the trends in a catchment scale.

关键词： Taihu Basin, nutrients, catchment resource inputs, SWAT model, simulation.