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Evaluation of nutrient limitation in aquatic ecosystems with nitrogen fixing bacteria

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Journal of Environmental Sciences 2006年第3期18卷 537-542页

作者： WU Gen-fu WU xue-chang XUAN Xiao-dong zhou xue-ping College of Life Sciences Zhejiang University Hangzhou 310012 China Science and Technology Committee of Zhejiang Hangzhou 310006 China Institute of Biotechnology Zhejiang University Hangzhou 310029 China

There has always been a great need for simple and accurate bioassays for evaluating nutrient limitation in aquatic ecosystems. Whereas organic carbon is usually considered to be the limiting nutrient for microbial growth in many aquatic ecosystems, there are, however, many water sources that are limited by phosphorus or nitrogen. A method named ＂nitrogen fixing bacterial growth potential＂（NFBGP） test, which is based on pre-culturing of autochthonous （target） microorganisms was described. The method was applied to evaluate phosphorus or nitrogen nutrient limitation in lake and sewage water samples using an isolate of the nitrogen fixing bacterium, Azorhizobium sp. WS6. The results corresponded well to those from the traditional algal growth potential （AGP） test and the bacterial regrowth potential （BRP） test, suggesting that the NFBGP test is a useful supplementary method for evaluating the limiting nutrient, especially phosphorus, in an aquatic environment.

关键词： environment monitoring nitrogen fixing bacterium limiting nutrient phosphorus growth potential

Multi-dimension apportionment of clean air “parade blue”phenomenon in Beijing

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Journal of Environmental Sciences 2018年第3期30卷 29-42页

作者： Yifeng xue Yong Wang xuefeng Li Hezhong Tian Lei Nie Xiaoqing Wu Junrui zhou Zhen zhou State Key Joint Laboratory of Environmental Simulation & Pollution Control School of Environment Beijing Normal University Beijing 100875 China National Engineering Research Center of Urban Environmental Pollution Control Beijing Municipal Research Institute of Environmental Protection Beijing 100037 China Center of Atmospheric Environmental Studies Beijing Normal University Beijing 100875 China Wuhan Environmental Protection Sciences Research Institute Wuhan 430015 China

The mass concentration and major chemical components of fine particulate matter were measured before,during and after Beijing＇s massive parade commemorating 70th anniversary of the Chinese Victory in World War II on September 3,*** emission inventory,positive matrix factorization（PMF）,observations from space and backward air mass trajectories were jointly applied to identify the major pollution sources and their temporal and spatial *** contributions of emissions variations and the meteorological conditions related to the＂parade blue＂phenomenon in Beijing and its surrounding areas were investigated in *** main cause of the decreased PM（2.5）mass concentration was attributed to the absolute reduction in emissions of primary air *** chemical composition of PM（2.5）varied significantly before,during and after the *** dust particles were well controlled,the secondary formation of PM（2.5）was reduced along with the controlled gaseous precursors＇emissions from vehicles and industrial sources during the temporary intensified control *** the parade period,the SO2and NO2column concentrations in Beijing and the surrounding areas decreased sharply,indicating that the coordinated reduction in primary emissions from the surrounding areas of Beijing played an important role in lowering the ambient concentration of SO2and NO2and accordingly lowered PM（2.5）and improved the regional air quality.A comparison of the temperature,humidity,and wind speed and direction during the same periods in 2014 and 2015 showed that the meteorological conditions positively influenced the achievement of＂parade blue＂.

关键词： PM2.5 Parade Blue in Beijing Emission reduction Air quality Source apportionment Meteorological conditions

Science Letters:Hydrothermal production of formic and acetic acids from syringol

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第8期11卷 613-618页

作者： Lu-ting PAN Zheng SHEN Lei WU Ya-lei ZHANG xue-fei zhou Fang-ming JIN MOE Key Laboratory of Yangtze River Water Environment State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science and Engineering Tongji University Shanghai 200092 China

The production of formic and acetic acids （or salts） by hydrothermal oxidation of syringol, a model compound for lignin, was investigated using a batch reactor. Results show that the highest yields of formic and acetic acids were, respectively, 59.6% and 11.3% at the reaction condition of 0.5 mol/L NaOH, 120% H2O2 supply and 280 ℃. These results will inform studies aiming to develop more enviromnental friendly lignin conversion processes by obtaining products beyond a CO2 end product.

关键词： Lignin Syringol Formic acid. Acetic acid. Hvdrothermal process

Mathematical model of the direct reduction of dust composite pellets containing zinc and iron

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International Journal of Minerals,Metallurgy and Materials 2013年第7期20卷 627-635页

作者： Xiu-wei An Jing-song Wang xue-feng She Qing-guo xue State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing School of Mechanical Engineering University of Science and Technology Beijing

Direct reduction of dust composite pellets containing zinc and iron was examined by simulating the conditions of actual production process of a rotary hearth furnace （RHF） in laboratory. A mathematical model was constructed to study the reduction kinetics of iron oxides and ZnO in the dust composite pellets. It was validated by comparing the calculated values with experimental results. The effects of furnace temperature, pellet radius, and pellet porosity on the reduction were investigated by the model. It is shown that furnace temperature has obvious influence on both of the reduction of iron oxides and ZnO, but the influence of pellet radius and porosity is much smaller. Model calculations suggest that both of the reduction of iron oxides and ZnO are under mixed control with interface reactions and Boudouard reaction in the early stage, but only with interface reactions in the later stage.

关键词： rotary hearth furnaces dust zinc ore pellets direct reduction process mathematical models kinetics

Reduction Behaviors of Pellets Under Different Reducing Potentials

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Journal of Iron and Steel Research International 2013年第12期20卷 12-18页

作者： ZUO Xiao-jian WANG Jing-song AN Xiu-wei SHE xue-feng xue Qing-guo State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

Owing to the change of gas composition in top gas recycling-oxygen blast furnaces compared with tradi- tional blast furnace, many attentions are attracted to the research on iron oxide reduction again. In order to study the influence of H2 and CO on the reduction behavior of pellets, experiments were conducted with H2-N2, CO N2 or H2-CO gas mixtures at 1 173 K by measuring the mass loss, respectively. It was found that the reduction degree in creased with increasing the ratio of H2 or CO in the gas mixture, but the reduction with hydrogen was faster than that with carbon monoxide. The reduction degree could reach 96. 720/00 after 65 rain for the reduction with 50~ H2 ＋ 50% N2, while it is only 53.37~ for the reduction with 50~ COq-50~ N2. The addition of hydrogen to carbon monoxide will accelerate the reduction because the hydrogen molecules are more easily chemisorbed and reacted with iron oxide than carbon monoxide. A scanning electron microscope was used to characterize the structures of reduced samples. Dense structure of iron was obtained in the reduction with hydrogen while the structure of iron showed many small fragments for the reduction with carbon monoxide. At the later stage of reduction with the gas mixtures containing carbon monoxide, the reduction curves showed a descending trend because the rate of carbon deposition caused by the thermal decomposition of carbon monoxide was faster than the rate of oxygen loss. Compared with the reduction with CO-N2 and H2 CO gas mixtures, H2 gas could enhance the carbon deposition while N2 gas would re- duce this phenomenon. The results of X-ray diffraction and chemical analysis demonstrated that the carbons are mainly in the form of cementite （FeaC） and graphite in reduced sample.

关键词： reduction pellet hydrogen carbon monoxide carbon deposition

An Online Model Correction Method Based on an Inverse Problem:PartⅡ——Systematic Model Error Correction

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Advances in Atmospheric Sciences 2015年第11期32卷 1493-1503页

作者： xue Haile SHEN xueshun CHOU Jifan State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences School of Atmospheric Sciences Lanzhou University Center for Numerical Prediction China Meteorological Administration

An online systematic error correction is presented and examined as a technique to improve the accuracy of real-time numerical weather prediction, based on the dataset of model errors （MEs） in past intervals. Given the analyses, the ME in each interval （6 h） between two analyses can be iteratively obtained by introducing an unknown tendency term into the prediction equation, shown in Part I of this two-paper series. In this part, after analyzing the 5-year （2001-2005） GRAPES- GFS （Global Forecast System of the Global and Regional Assimilation and Prediction System） error patterns and evolution, a systematic model error correction is given based on the least-squares approach by firstly using the past MEs. To test the correction, we applied the approach in GRAPES-GFS for July 2009 and January 2010. The datasets associated with the initial condition and SST used in this study were based on NCEP （National Centers for Environmental Prediction） FNL （final） data. The results indicated that the Northern Hemispheric systematically underestimated equator-to-pole geopotential gradient and westerly wind of GRAPES-GFS were largely enhanced, and the biases of temperature and wind in the tropics were strongly reduced. Therefore, the correction results in a more skillful forecast with lower mean bias and root-mean-square error and higher anomaly correlation coefficient.

关键词： model error past data inverse problem error estimation model correction GRAPES-GFS

An Online Model Correction Method Based on an Inverse Problem:Part I—Model Error Estimation by Iteration

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Advances in Atmospheric Sciences 2015年第10期32卷 1329-1340页

Errors inevitably exist in numerical weather prediction （NWP） due to imperfect numeric and physical parameterizations. To eliminate these errors, by considering NWP as an inverse problem, an unknown term in the prediction equations can be estimated inversely by using the past data, which are presumed to represent the imperfection of the NWP model （model error, denoted as ME）. In this first paper of a two-part series, an iteration method for obtaining the MEs in past intervals is presented, and the results from testing its convergence in idealized experiments are reported. Moreover, two batches of iteration tests were applied in the global forecast system of the Global and Regional Assimilation and Prediction System （GRAPES-GFS） for July-August 2009 and January-February 2010. The datasets associated with the initial conditions and sea surface temperature （SST） were both based on NCEP （National Centers for Environmental Prediction） FNL （final） data. The results showed that 6th h forecast errors were reduced to 10% of their original value after a 20-step iteration. Then, off-line forecast error corrections were estimated linearly based on the 2-month mean MEs and compared with forecast errors. The estimated error corrections agreed well with the forecast errors, but the linear growth rate of the estimation was steeper than the forecast error. The advantage of this iteration method is that the MEs can provide the foundation for online correction. A larger proportion of the forecast errors can be expected to be canceled out by properly introducing the model error correction into GRAPES-GFS.

关键词： model error past data inverse problem error estimation model correction GRAPES-GFS

Eulerian–Lagrangian simulation of bubble coalescence in bubbly flow using the spring-dashpot model

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Chinese Journal of Chemical Engineering 2017年第3期25卷 249-256页

作者： Jing xue Feiguo Chen Ning Yang Wei Ge State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesP.O.Box 353Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The Eulerian–Lagrangian simulation of bubbly flow has the advantage of tracking the motion of bubbles in continuous fluid, and hence the position and velocity of each bubble could be accurately acquired. Previous simulation usually used the hard-sphere model for bubble–bubble interactions, assuming that bubbles are rigid spheres and the collisions between bubbles are instantaneous. The bubble contact time during collision processes is not directly taken into account in the collision model. However, the contact time is physically a prerequisite for bubbles to coalesce, and should be long enough for liquid film drainage. In this work we applied the spring-dashpot model to model the bubble collisions and the bubble contact time, and then integrated the spring-dashpot model with the film drainage model for coalescence and a bubble breakage model. The bubble contact time is therefore accurately recorded during the collisions. We investigated the performance of the spring-dashpot model and the effect of the normal stiffness coefficient on bubble coalescence in the *** results indicate that the spring-dashpot model together with the bubble coalescence and breakage model could reasonably reproduce the two-phase flow field, bubble coalescence and bubble size distribution. The influence of normal stiffness coefficient on simulation is also discussed.

关键词： Bubble column Spring-dashpot model CoalescenceBreak-up Bubble size distribution

Characteristics of Seismic Activity in a 3-Dimensional Space before the Wen'an Earthquake,Hebei Province by Relocation of Small Earthquakes in the China's Capital Area

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Earthquake Research in China 2010年第4期24卷 404-414页

作者： xue Yan zhou Longquan Ma Hongsheng Liu Jie Institute of Geophysics China Earthquake Administration Beijing 100081 China China Earthquake Networks Center Beijing 100045 China Institute of Earthquake Science China Earthquake Administration Beijing 100036 China

Characteristics of seismic activity before the M5. 1 earthquake in Wen＇an, Hebei Province on July 4, 2006 are analyzed by relocation of small earthquakes in the China＇s capital area, and some results are obtained as follows：① The seismic activity of ML ≥ 3.0 in the middle part of the Hebei plain seismic belt displayed a feature of strengthening （ lasting 43 months） quiescence （17 months） five years before the Wen＇an earthquake. Simultaneously, the strain release curve showed a variation process of accelerating-flatting. ② A seismogenic gap in a three-dimensional space, located at the depth of 15km - 20km, with 70km long in latitude direction and 90km long in longitude orientation, was formed by M≥2.0 earthquakes four years prior to the Wen＇an earthquake. The initial rupture point of the Wen＇an earthquake is situated at the bottom of the gap. ③ The focal depths of earthquakes with ML ≥ 2. 0 in the middle part of the Hebei plain seismic belt gradually increased from 10km to 30kin during the period from April, 2003 to October, 2004. Meanwhile, the seismic activity obviously strengthened in the middle and lower crust （from 20km to 30km in depth）.

关键词： Wen'an earthquake Small earthquake relocation Seismic gap Focal depth