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Thresholds of geographic environmental elements in sediment yield of drainage basins

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science china Earth sciences 2005年第2期48卷 230-240页

作者： CHEN Hao, ZHOU Jinxing, CAI Qiangguo, LU Zhongchen & LI Zhongyan Institute of Geographic sciences and Natural Resources research, Chinese Academy of sciences, Beijing 100101, china Institute of Forestry science, Chinese Academy of Forestry science, Beijing 100091, china research center for Eco-Environment sciences, Chinese Academy of sciences, Beijing 100085, china Computing Institute of science and Engineering, North china Electric Power University, Beijing 102206, china 1. Institute of Geographic sciences and Natural Resources research Chinese Academy of Sciences 100101 Beijing China 2. Institute of Forestry science Chinese Academy of Forestry Science 100091 Beijing China 3. research center for Eco-Environment sciences Chinese Academy of Sciences 100085 Beijing China 4. Computing Institute of science and Engineering North China Electric Power University 102206 Beijing China

Threshold of environmental elements in drainage basin sediment yield refers to, under effect of climate, underlying surface and human activity, a turning point of abrupt changes in drainage sediment yield related to environmental element characteristics. Previous studies on threshold of sediment yield of relevant drainage basins were mainly concentrated on impact of natural zones with a few researches on impact of other environmental elements. Particularly studies on compound environmental element threshold in drainage basin sediment yield remain blank today. Studies indicate that sediment yield in drainage basins is affected by compound interactions and complex actions. Based on single element analysis, the present paper gives quantitatively compound threshold of environmental elements affecting sediment yield of the drainage basin between Hekouzhen and Tongguan in the middle Yellow River by the method of multi-variant, polynomial formula regression analysis.

关键词： middle Yellow River, environmental element, sediment, sediment delivery mudule, threshold.

Effect of climatic change on snowmelt runoffs in mountainous regions of inland rivers in Northwestern china

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science china Earth sciences 2006年第8期49卷 881-888页

作者： WANG Jian1 & LI Shuo2 1. Cold and Arid Regions environmental and Engineering research Institute, Chinese Academy of sciences, Lanzhou 730000, china 2. College of Geography, Nanjing Normal University, Nanjing 210097, china 1. Cold and Arid Regions environmental and Engineering research Institute Chinese Academy of Sciences Lanzhou 730000 China 2. College of Geography Nanjing Normal University Nanjing 210097 China

Climatic change has significant impacts on snow cover in mid-latitude mountainous re- gions, in the meantime, spatial and temporal changes of snow cover and snowmelt runoffs are con- sidered as sensitive indicators for climatic change. In this study, the upper Heihe Watershed in the Qilian Mountains was selected as a typical area affected by snow cover and snowmelt runoffs in northwestern china. The changes in air temperatures, precipitation, snowfall and spring snowmelt runoffs were analyzed for the period from 1956 to 2001. The results indicate that climatic warming was apparent, particularly in January and February, but precipitation just fluctuated without a clear trend. The possible changes of snowmelt runoffs in the upper Heihe watershed in response to a warming of 4℃ were simulated using Snowmelt Runoff Model (SRM) based on the degree-day factor algorithm. The results of the simulation indicate that a forward shifting of snow melting season, an increase in water flows in earlier melting season, and a decline in flows in later melting season would occur under a 4℃ warming scenario.

关键词： climatic changes, snowmelt runoff, SRM model, upper Heihe Watershed, simulating.

Effects of N Forms and Rates on Vegetable Growth and Nitrate Accumulation

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Pedosphere 2003年第4期13卷 309-316页

作者： WANG Zhao-Hui and LI Sheng-XiuCollege of Resources and environmental sciences, Northwestern science and technology University of Agriculture and Forestry, Yangling 712100 (china). E-mail: w-zhaohui@*** College of Resources and environmental sciences Northwestern Science and Technology University of Agriculture and Forestry Yangling 712100 (China)

Experiments were carried out on a vegetable field with Peking cabbage(Brassica pekinensis (Lour.) Rupr.), cabbage (Brassica, chinensis var. oleifcra Makino and nemoto),green cabbage (Brassica chinensis L.), spinach (Spinacia oleracea L.) and rape(Brassica campestrisL.) to study the effects of N forms and N rates on their growth and nitrate accumulation. Theresults indicated that application of ammonium chloride, ammonium nitrate, sodium nitrate and ureasignificantly increased the yields and nitrate concentrations of Peking cabbage and *** no significant difference was found in the yields after application of the 4 N forms,nitrate N increased nitrate accumulation in vegetables much more than ammonium N. The vegetableyields were not increased continuously with N rate increase, and oversupply of N reduced the plantgrowth, leading to a yield decline. This trend was also true for nitrate concentrations in somevegetables and at some sampling times. However, as a whole, the nitrate concentrations in vegetableswere positively correlated with N rates. Thus, addition of N fertilizer to soil was the major causefor increases in nitrate concentrations in vegetables. Nitrate concentrations were much higher inroots, stems and petioles than in blades at any N rate.

关键词： N form N rate nitrate accumulation vegetable yield

Factors governing formation of todorokite at atmospheric pressure

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science china Earth sciences 2005年第10期48卷 1678-1689页

作者： CUI Haojie1, FENG Xionghan1, LIU Fan1, TAN Wenfeng1 & HE Jizheng2 1. College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, china 2. research center for Eco-environmental sciences, Chinese Academy of sciences, Beijing 100085, china College of Resources and Environment Huazhong Agricultural University Wuhan china research center for Eco-environmental sciences Chinese Academy of sciences Beijing china

Todorokite commonly occurs in Earth surface environments. The factors governing formation of todorokite, such as reaction temperature, metal ions, dissolved O2 and pH, were investigated in this paper. Results showed that the forming rate of todorokite and its crystallinity decreased with falling reaction temperature, and the effect of temperature was more significant than that of other parameters. Nature of metal ions in the interlayer of buserite precursor and the structure of the buserite precursor obviously affected buserite transformation into todorokite. Weak bonding between the metal ions and MnO6 layer of buserite was favorable to todorokite formation. The rate of todorokite formation was promoted at a lower temperature with appropriate bubbling of O2. The pH in the system slightly influenced the todorokite formation, and todorokite could also be formed in a weak alkali medium or in a slightly acidic medium. Aged buserite pre-cursor more easily form todorokite than the unaged one.

关键词： todorokite, buserite, manganese oxide mineral, atmospheric pressure, transformation.

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF FREE SURFACE VORTEX

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Journal of Hydrodynamics 2008年第4期20卷 485-491页

An experimental model was set up to investigate the formation and evolution of the free surface vortex. A Particle Image Velocimetry （PIV） was used to measure the free surface vortex flow field at different development stages. Flow visualization was used to locate the vortex position and find its structure. Empirical formulas about the critical submergence and the whole field structure were obtained. It is found that the tangential velocity distribution is similar to that of the Rankine vortex and the radial velocity changes little in the vortex functional scope. Vortex starts from the free surface and gradually intensifies to air entrainment vortex. The vortex core moves during the formation and evolution of the free surface vortex. Based on the experimental model, the vortex position and structure were predicted by numerical simulation combined with a vortex model and compared with that of the experiments, which shows satisfactory agreement.

关键词： free surface vortex Particle Image Velocimetry (PIV) numerical simulation rankine vortex

Oceanic iron fertilization: one of strategies for sequestration atmospheric CO_2

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Acta Oceanologica Sinica 2003年第1期22卷 57-68页

作者： Song Jinming Marine Ecology and environmental science Lab, Institute of Oceanology, Chinese Academy of sciences, Qingdao 266071, china Chinese Acad Sci Inst Oceanol Marine Ecol & Environm Sci Lab Qingdao 266071 Peoples R China

Carbon cycle is connected with the most important environmental issue of Global Change.As one of the major carbon reservoirs, oceans play an important part in the carbon cycle. In recent years, iron seems to give us a good news that oceanic iron fertilization could stimulate biological productivity as CO2 sink of human-produced CO2. Oceanic iron fertilization experiments have verified that adding iron into high nutrient low chlorophyll (HNLC) seawaters can increase phytoplankton production and export organic carbon, and hence increase carbon sink of anthropogenic CO2, to reduce global warming. In sixty days, the export organic carbon could reach 10 000 times for adding iron by model prediction and in situ experiment, i.e. the atmospheric CO2 uptake and inorganic carbon drawdown in upper seawaters also have the same magnitude. Therefore, oceanic iron fertilization is one of the strategies for increasing carbon sink of anthropogenic CO2. The paper is focused on the iron fertilization, especially in situ ocean iron experiments in order that the future research is more efficient.

关键词： Iron fertilization phytoplankton production export organic carbon CO2 sink

Preliminary study on nanodiatom in the Taiwan Strait

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Acta Oceanologica Sinica 2000年第1期19卷 91-98页

作者： Guo Jian Huang Bangqin Cheng Zhaodi Hong Huasheng (1. Department of Biology, Xiamen University, Xiamen 361005, china. 2. research Lab of SEDC on Marine Ecological Environment, environmental science research center, Xiamen University, Xiamen 361005, china. Department of Biology Xiamen University Xiamen 361005 China Res. Lab. SEDC Mar. Ecol. Environ. Environ. Science Research Center Xiamen University Xiamen 361005 China

The preliminary study on nanodiatom in the Taiwan Strait was carried out using transmission electron microscopy (TEM) in February 1995. Thirty-three species of nanodiatom (20 μm) were identified, among which, 6 were new recorders in china. The dominant species were Minidiscus comicus Takano and Thalassiosira tenera Proschdinae -- Lavrenko in the northern Taiwan Strait (NTS), Minidiscus trioculatus (F. J. R. ) Hasle and Natvicula climacospheniae both in the southern Taiwan Strait (STS). Abundance of nanodiatom was much more than that of microdiatom (>20 μm), and the abundance of nanodiatom in NTS is higher than that in STS. The highest abundance of nanodiatom was at the depth of 10 m of N33o in NTS, while at the depth of 20 m of S105 in STS. The vertical distribution of nano- and micro-diatom of NCI showed that the peak was at the depth of 30 m.

关键词： Nanediatom Taiwan Strait abundance species diversity

Analysis of sea surface temperature fronts in the Taiwan Strait and its adjacent area using an advanced edge detection method

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science china Earth sciences 2010年第7期53卷 1008-1016页

作者： PI QingLing1,2,3 & HU JianYu1,2 1 State Key Laboratory of Marine environmental science, Xiamen University, Xiamen 361005, china 2 Department of Oceanography, Xiamen University, Xiamen 361005, china 3 china Communications Construction Company First Harbor Consultants CO., LTD., Tianjin 300222, china 1. State Key Laboratory of Marine environmental science Xiamen University Xiamen 361005 China2. Department of Oceanography Xiamen University Xiamen 361005 China3. China Communications Construction Company First Harbor Consultants CO. LTD. Tianjin 300222 China

A morphology-based edge detection method has been used to study sea surface temperature (SST) fronts in the Taiwan Strait and its adjacent area. The method is based on mathematical morphology with multi-dimensional and multi-structural elements. Using six years’ SST data from September 2002 to August 2008, we distinguished the large SST front like Kuroshio Front as well as the smaller ones: namely Taiwan Bank Front, Zhe-Min Coastal Front and Zhang-Yun Ridge Front. The seasonal and monthly variations of these fronts were also studied. Generally, the SST fronts are stronger in winter but weaker in summer. And the fronts are at their active stage during the period from January to May but at their declining stage during the period from July to October.

关键词： SST front remote sensing edge detection Taiwan Strait Kuroshio

Spatial distribution of 10m firn temperature in the Antarctic Ice Sheet

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science china Earth sciences 2011年第5期54卷 655-666页

作者： WANG YeTang1,3 & HOU ShuGui2,3 1 Shandong Marine Fisheries research Institute,Yantai 264006,china 2 MOE,Key Laboratory for Coast and Island Development,School of Geographic and Oceanographic sciences,Nanjing University,Nanjing 210093,china 3State Key Laboratory of Cryospheric science,Cold and Arid Regions environmental and Engineering research Institute,Chinese Academy of sciences,Lanzhou 730000,china 1. Shandong Marine Fisheries research Institute Yantai 264006 China3. State Key Laboratory of Cryospheric Science Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China2. MOE Key Laboratory for Coast and Island Development School of Geographic and Oceanographic Sciences Nanjing University Nanjing 210093 China

A database of Antarctic 10 m firn temperature was constructed using available borehole temperature measurements with data quality control to extend knowledge of Antarctic climate. Slopes from a high-resolution digital elevation model and the main ice divide were used to delineate main drainage sectors across Antarctica. In each drainage sector, a quantitative relationship between temperature and latitude, longitude and altitude was established using available tim temperature data. Quantitative relationships incorporating other factors affecting Antarctic air temperature such as atmospheric circulation and small-scale to- pography were used to derive a 10-km resolution grid map of surface temperature. The resulting temperature patterns presented a reasonable depiction of both large and small-scale variations in Antarctic 10 m firn temperature. This map is useful for many spatial variation studies, Antarctic ice sheet models, and comparison with satellite-derived temperature data and outputs of atmospheric general circulation models.

关键词： Antarctica 10 m firn temperature spatial distribution