海水人工湿地系统脱氮效果与基质酶活性的相关性   总被引：1，自引：0，他引：1  

吴俊泽  王艳艳  李悦悦  祝佳玄  曲克明  崔正国 《海洋科学》2019,43(5):36-44

利用海水人工湿地系统处理海水养殖外排水,分析了人工湿地对不同形态氮的净化效果,探讨了人工湿地表层基质酶活性变化及其对系统脱氮效果的影响。选取互花米草作为人工湿地植物,煤渣、珊瑚石和细砂作为人工湿地基质,实验期间连续进水,系统运行稳定。研究结果表明:海水人工湿地系统对氨氮(NH4-N)、亚硝态氮(NO2-N)、硝态氮(NO3-N)、总氮(TN)和可溶性有机氮(DON)去除效果显著,去除率分别为(99.6±0.7)%、(99.9±0.0)%、(98.2±2.0)%、(92.6±1.5)%和(86.1±4.8)%。人工湿地表层基质下行池脱氢酶、硝酸还原酶和脲酶的酶活性均高于上行池,下行池对污染物的去除效果更好。脱氢酶活性与海水人工湿地系统氨氮的去除有关;硝酸还原酶活性影响着海水人工湿地硝态氮的去除;脲酶活性与人工湿地总氮和硝态氮的去除存在明显相关趋势。下行池硝酸还原酶和脲酶的酶活性间具有显著相关性(r=0.76, P0.05)。人工湿地微生物种类丰富,下行池微生物多样性高于上行池,植物根部微生物多样性最高,提高了系统脱氮的效率。上述研究结果将有助于阐明海水人工湿地系统中不同形态氮的迁移转化机理。  相似文献   

Scaling-laws of Radio Spike Bursts and Their Constraints on New Solar Radio Telescopestwo     

Tan Bao-lin  Cheng Jun  Tan Cheng-ming  Kou Hong-xiang 《Chinese Astronomy and Astrophysics》2019,43(1):59-74

Radio observation is one of important methods in solar physics and space science. Sometimes, it is almost the sole approach to observe the physical processes such as the acceleration, emission, and propagation of non-thermal energetic particles, etc. So far, more than 100 solar radio telescopes have been built in the world, including solar radiometers, dynamic spectrometers, and radioheliographs. Some of them have been closed after the fulfillment of their primary scientific objectives, or for their malfunctions, and thus replaced by other advanced instruments. At the same time, based on some new technologies and scientific ideas, various kinds of new and much more complicated solar radio telescopes are being constructed by solar radio astronomers and space scientists, such as the American E-OVSA and the solar radio observing system under the framework of Chinese Meridian Project II, etc. When we plan to develop a new solar radio telescope, it is crucial to design the most suitable technical parameters, e.g., the observing frequency range and bandwidth, temporal resolution, frequency resolution, spatial resolution, polarization degree, and dynamic range. Then, how do we select a rational set of these parameters? The long-term observation and study revealed that a large strong solar radio burst is frequently composed of a series of small bursts with different time scales. Among them, the radio spike burst is the smallest one with the shortest lifetime, the narrowest bandwidth, and the smallest source region. Solar radio spikes are considered to be related to a single magnetic energy release process, and can be regarded as an elementary burst in solar flares. It is a basic requirement for the new solar radio telescope to observe and discriminate these solar radio spike bursts, even though the temporal and spatial scales of radio spike bursts actually vary with the observing frequency. This paper presents the scaling laws of the lifetime and bandwidth of solar radio spike bursts with respect to the observing frequency, which provide some constraints for the new solar radio telescopes, and help us to select the rational telescope parameters. Besides, we propose a spectrum-image combination mode as the best observation mode for the next-generation solar radio telescopes with high temporal, spectral, and spatial resolutions, which may have an important significance for revealing the physical essence of the various non-thermal processes in violent solar eruptions.  相似文献   

淡化浓海水日晒盐田原核微生物多样性分析     

秦乐宁  黄鑫洁  朱大玲  侍亚敏  唐娜  王学魁 《海洋科学》2019,43(5):27-35

海滨日晒盐田具有稳定且独特的生态系统。淡化浓海水排入盐田制盐,对盐田生态系统的稳定及盐田的可持续发展具有一定的影响。本研究分析天津汉沽淡化浓海水日晒盐田不同季节不同盐度盐池原核微生物多样性现状及群落结构变化,以期为评估淡化浓海水对盐田原核微生物群落影响提供理论依据。采用温度梯度凝胶电泳和序列测定等方法,分析不同月份不同盐度盐池中细菌和古菌的多样性与群落结构变化。分别采用香农-威纳指数、加权丰富度指数和均匀度指数分析盐田微生物群落多样性、丰富度和均匀度。结果表明,淡化浓海水和溴后水中均未检测出细菌和古菌。不同月份不同盐度盐池样本中细菌多样性变化不大,优势菌主要为γ-变形菌门(γ-Proteobacteria)中的Spiribacter salinus和Pseudoalteromonassp.;古菌仅出现在盐度最高的Ⅶ号盐池中,优势古菌为广古菌门(Euryarchaeota)的Halogeometricum sp.。天津汉沽淡化浓海水日晒盐田中细菌的多样性和丰富度较低,春夏两季细菌群落结构较为稳定,秋冬季节细菌群落结构变化明显。盐度不同的盐池中细菌群落结构变化较大,随着盐度逐渐升高, Spiribacter salinus逐渐取代Pseudoalteromonas sp.成为占主要地位的优势菌种。  相似文献   

郯庐断裂带苏皖段重力变化的多尺度分解与构造活动分析     

林承灏  黎哲君  徐如刚  袁泉 《大地测量与地球动力学》2019,39(9):884-889

基于多期绝对重力与相对重力联测资料，获取不同时空尺度的郯庐断裂带苏皖段及周边地区重力场动态变化，采用小波多尺度分解方法计算不同深度的重力变化，结合区域地质构造，从深度层次的横向变化与时间尺度的纵向变化2个方面进行分析。结果表明，研究区重力变化主要由中、上地壳密度变化或断裂构造活动引起。沿郯庐断裂带苏皖段走向断裂活动分布不均，受周边深大断裂带交切作用的影响表现出明显的分段活动特征。淮阴-响水口断裂、滁河断裂等深大活动断裂带构造活动对局部重力变化具有一定的控制作用，沿断裂带走向分布有明显的重力变化梯度带；郯庐断裂带郯城-泗县段、大别山构造带霍山-六安及江苏溧阳-镇江地区在小波细节动态变化中存在重力变化梯度带异常区，但强度不高，考虑到多条深大断裂交切于此，后期需要重点关注。  相似文献   

A high-precision heuristic model to detect home and work locations from smart card data     

Nilufer Sari Aslam  Tao Cheng  James Cheshire 《地球空间信息科学学报》2019,22(1):1-11

Smart card-automated fare collection systems now routinely record large volumes of data comprising the origins and destinations of travelers. Processing and analyzing these data open new opportunities in urban modeling and travel behavior research. This study seeks to develop an accurate framework for the study of urban mobility from smart card data by developing a heuristic primary location model to identify the home and work locations. The model uses journey counts as an indicator of usage regularity, visit-frequency to identify activity locations for regular commuters, and stay-time for the classification of work and home locations and activities. London is taken as a case study, and the model results were validated against survey data from the London Travel Demand Survey and volunteer survey. Results demonstrate that the proposed model is able to detect meaningful home and work places with high precision. This study offers a new and cost-effective approach to travel behavior and demand research.  相似文献   

绿色空间对休闲性体力活动影响的社区分异 ——以广州市为例     

戴颖宜  朱战强  周素红 《热带地理》2019,39(2):237-246

以广州市20个典型社区为例，构建多元线性回归模型，探讨了绿色空间对居民休闲性体力活动的影响，并剖析绿色空间对不同类型社区居民休闲性体力活动影响的作用机制。结果发现：1）不同类型社区居民的休闲性体力活动水平存在明显差异，低档社区的为782.99 MET-min/w，中档社区的为871.70 MET-min/w，高档社区的为1 227.91 MET-min/w；2）影响不同类型社区居民休闲性体力活动水平的绿色空间因素有所不同，低档社区、中档社区和高档社区的显著因子分别为“到最近公园广场距离”“邻里绿化覆盖率”和“健身活动设施数量”；3）绿色空间对休闲性体力活动水平影响的作用机制存在社区差异，低档社区居民休闲性体力活动主要受到成本作用的约束，中档社区居民主要受绿化环境作用影响，而高档社区居民主要受机会作用影响。  相似文献   

用日全食光谱探测太阳中低层大气对局部热动平衡的偏离          下载免费PDF全文

刘曦  屈中权  宋智明 《天文学报》2021,62(1):9-109

在太阳大气不同层次连续光谱中叠加有丰富的发射线或吸收线,对这些谱线轮廓进行反演分析可以探测太阳大气的化学成分和物理状态.太阳大气的色球及过渡区由于其密度低难以建立热动平衡,建立相应的大气模型需要采用非局部热动平衡(Non-Local Thermodynamic Equilibrium,N-LTE)理论.根据相对偏离因子计算来研究太阳中低层大气偏离局部热动平衡(Local Thermodynamic Equilibrium,LTE)分布的情况.首先对日全食观测过程中得到色球和过渡区不同高度形成的两条光谱数据进行反演,得到确定观测谱线的参数信息,如连续谱源函数、谱线源函数、多普勒宽度和由此推出的等效动力学温度;根据这些反演出的谱线参量计算出二维视场内每个空间采样点偏离LTE状态的定量结果;其次,根据用于观测的积分视场单元光纤排布阵列重构出辐射强度、等效动力学温度和相对偏离因子二维分布.结果显示:在局部小区域,温度分布和相对偏离因子的分布存在较强相关性,而与辐射强度分布无明显相关.从两条谱线导出的等效温度和相对偏离因子分布存在明显的差异.这两种二维分布揭示出太阳大气某些小尺度区域具有较强的结构性和复杂性,为进一步理解太阳中低层大气物理提供了一种新的视角.  相似文献   

利用跨断层形变资料研究天山中段断层现今活动特征     

韩桂红  滕海涛  高歌  李桂荣  张治广 《大地测量与地球动力学》2019,39(1):72-76

利用2001年以来天山中段多个跨断层形变场地的测量资料，从断层运动方向和断层平均速率2个方面分析天山中段3条断层现今活动特征。结果表明，霍玛吐断裂呼图壁段断层的活动性质为正、逆断和左、右旋交替活动；北轮台-辛格尔断裂库尔勒段断层表现为右旋运动特征，活动性质为逆断性；妖魔山F2断裂乌鲁木齐段的断层活动性质以逆断为主。妖魔山F2断裂乌鲁木齐段断层的活动程度最高，霍玛吐断裂呼图壁段最低。霍玛吐断裂、北轮台-辛格尔断裂、妖魔山F2断裂垂直方向上基本均处于张性变化，前两者水平向处于挤压状态；断层活动速率的时间进程具有阶段性特征，各个时间段转折点有较好的匹配性。  相似文献   

A shift towards wetter and windier conditions in southern Sweden around the prominent solar minimum 2750 cal a BP          下载免费PDF全文

ANETTE MELLSTRÖM  NATHALIE VAN DER PUTTEN  RAIMUND MUSCHELER  RIXT DE JONG  SVANTE BJÖRCK 《第四纪科学杂志》2015,30(3):235-244

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Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions          下载免费PDF全文

Xiong Zhang  Jean‐Louis Briaud 《国际地质力学数值与分析法杂志》2015,39(13):1369-1409

Shrink–swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil–foundation–building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro‐mechanical stress analysis is used to simulate the volume change of shrink–swell soils due to both mechanical stress and water content variations. Coupled hydro‐mechanical stress‐jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2‐year period is presented. Finally, a three‐dimensional simulation is made for a virtual residential building on shrink–swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献