检索结果-南通市图书馆

temporal variation of soil water and its influencing factors in hilly area of Chongqing,China

International Journal of Agricultural and Biological Engineering 2014年第4期7卷 47-59页

作者： Zhong Shouqin Zhang Weihua Lv Jiake Wei Chaofu College of Resources and Environment Southwest UniversityChongqing 400700China School of Computer and Information Science Southwest UniversityChongqing 400700China

The paper studied the temporal variation of soil water content and its influencing factors in hilly area of Chongqing by the yearly data of 2006 and *** to precipitation anomaly percentage,the year 2006 was a dry year and 2007 a normal *** the dry year 2006,the variations of soil moisture in all three layers(0-10 cm,10-20 cm,20-40 cm)were medium(10%variation in the layer of 0-10 cm was strong(CV>30%),and those of the two deeper layers were weak(CVvariation of soil moisture in the humid area was large in the dry year and small in the wet *** probability distributions of soil moisture in all three layers in both dry and normal years showed single-peak ***,peak locations and values varied with different layers and *** factors affecting the temporal variation of soil moisture in the 0-10 cm layer,during March to May,the meteorological factors including temperature,sunshine and precipitation were all inversely correlated with soil water content *** correlations with average temperature and accumulated temperature were both highly significant P<0.01(P=0.00).The inverse correlations with sunshine and precipitation were significant P<0.05(P=0.01).Among soil physical properties,except for bulk density which was inversely correlated with soil moisture,all other properties were positively *** material was positively correlated with soil moisture,which suggested that organics had the sponge effect and contributed to soil water storage and *** the period of June to September,there was no significant correlation between soil water content and total *** meteorological factors of temperature,accumulated temperature and sunshine were all inversely and highly significantly correlated with soil water content P<0.01(P=0.00).

关键词： soil water temporal variation influencing factors hilly area

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

temporal variation and Source Identification of Black Carbon at Lin'an and Longfengshan Regional Background Stations in China

引用

Journal of Meteorological Research 2017年第6期31卷 1070-1084页

作者： Siyang CHENG Yaqiang WANG Xingqin AN State Key Laboratory of Severe Weather/Key Laboratory of Atmospheric Chemistry of China Meteorological Administration Chinese Academy of Meteorological SciencesBeijing 100081

Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at background stations in China and its source area identification are lacking. In this paper, we use 2-yr BC observations from two background stations, Lin＇an （LAN） and Longfengshan （LFS）, to perform the investigation. The results show that the mean diurnal variation of BC has two significant peaks at LAN while different characteristics are found in the BC vari- ation at LFS, which are probably caused by the difference in emission source contributions. Seasonal variation of monthly BC shows double peaks at LAN but a single peak at LFS. The annual mean concentrations of BC at LAN and LFS decrease by 1.63 and 0.26 μg m 3 from 2009 to 2010, respectively. The annual background concentration of BC at LAN is twice higher than that at LFS. The major source of the LAN BC is industrial emission while the source of the LFS BC is residential emission. Based on transport climatology on a 7-day timescale, LAN and LFS stations are sensitive to surface emissions respectively in belt or approximately circular area, which are dominated by summer monsoon or colder land air flows in Northwest China. In addition, we statistically analyze the BC source regions by using BC observation and FLEXible PARTicle dispersion model （FLEXPART） simulation. In summer, the source regions of BC are distributed in the northwest and south of LAN and the southwest of LFS. Low BC concentration is closely related to air mass from the sea. In winter, the source regions of BC are concentrated in the west and south of LAN and the northeast of the threshold area of stot at LFS. The cold air mass in the northwest plays an important role in the purification of atmospheric BC. On a yearly scale, sources of BC are approximately from five provinces in the northwest/southeast of LAN and the west of LFS. These f

关键词： black carbon temporal variation source region atmospheric background station

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

temporal variation of atmospheric CH_4 and the potential source regions at Waliguan, China

引用

Science China Earth Sciences 2013年第4期56卷 727-736页

作者： ZHANG Fang ZHOU LingXi XU Lin College of Global Change and Earth System Science Beijing Normal University Chinese Academy of Meteorological Sciences (CAMS) China Meteorological Administration (CMA)

We used a revised dataset of the atmospheric CH4 mixing ratios that were continuously measured at Mount Waliguan Baseline Observatory of western China during 2002-2006 to study the temporal variations and the potential sources regions of ambient CH4 . Approximately 58% observed values were filtered as background data by applying a robust local regression mathematic procedure. The median, 10% and 90% percentiles of CH4 background mixing ratios were 1831.8, 1820.7 and 1843.5 ppb (109molmol1 ), respectively; the atmospheric CH4 time series showed large variations with a fluctuation of 200 ppb (maximum minus minimum), but the background CH4 exhibited a much smaller variation (about 38 ppb), indicating strong impacts from local or regional sources and sinks. Ambient CH4 displayed significant diurnal variations in different seasons during 2002-2006, as was the combined result of changes of nearby sources/sinks and local meteorological circulation. The averaged CH4 seasonal cycle showed minimum in spring and winter, maximum in summer (from June to August), as is completely opposite to that observed at Mauna Loa and Niwot Ridge. The incongruous variation should be attributed to enhancing regional/local sources (e.g., herd) around the site as well as the dominant air flow from the polluted north/northeastern region (e.g., Xining and Lanzhou city) in summer. Another possible reason is, compared to Mauna Loa and Niwot Ridge, the photochemical reaction at Waliguan is weaker. An analysis of 5 d back-trajectory (500 hPa) showed that the episode of high CH 4 mixing ratios was associated with advection from the heavily populated regions east or southeast (e.g., Xining and Lanzhou) of Waliguan and northwest of Qinghai via Ge'ermu urban area where growing industrial activities as well as crops residue burning provide large sources of CH4 , suggesting a large source area; the low values were observed most frequently when air masses originated from the sparsely populated Tibet and sout

关键词： background atmosphere methane (CH4) temporal variation sourcessinks trajectory analysis

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Spatio-temporal variation of spring phenology in Tibetan Plateau and its linkage to climate change from 1982 to 2012

引用

Journal of Mountain Science 2016年第1期13卷 83-94页

作者： DING Ming-jun LI Lan-hui NIE Yong CHEN Qian ZHANG Yi-li Key Laboratory of Poyang Lake Wetland and Watershed Research Ministry of Education and School of Geography and EnvironmentJiangxi Normal UniversityNanchang 330022China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

The influence of climate change on vegetation phenology is a heated issue in current climate change *** used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season(SGS) over the Tibetan Plateau(TP) from 1982 to 2012 and to analyze its relationship with temperature and *** significant trend was observed in the SGS at the regional scale during the study period(R^2 = 0.03,P = 0.352).However,there were three time periods(1982-1999,1999-2008 and 2008-2012) with identifiable,distinctly different *** with a significant advancing trend were mainly scattered throughout the humid and semi-humid areas,whereas the regions with a significant delaying trend were mostly distributed throughout the semi-arid *** analysis showed that the response of the SGS to climate change varies *** SGS was significantly correlated with the spring temperature and the start of the thermal growth season(STGS) in the relatively humid *** increasing aridity,theimportance of the spring temperature for the SGS gradually ***,the influences of precipitation and winter temperature on the SGS were complicated across the plateau.

关键词： Spring phenology Spatial pattern temporal variation Climate change CorrelationTibetan Plateau (TP)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Spatio-temporal variation of trace elements distributed over surface water of Upper Ganga River Basin in Western Himalayan Region

引用

Journal of Mountain Science 2023年第1期20卷 145-162页

作者： Deepika DIMRI Ambika KUMAR DeepakKumar MISHRA Archana SHARMA Doon University Dehradun248012India Bhagalpur National College Bhagalpur812007India

The rivers draining from the Himalayan range distribute enormous amount of fresh water to the people living in downstream *** metals flowed with river water can lead to serious impact on ecological system and human ***,the documentation on trace elements of Himalayan rivers is inadequately *** current study deals with the spatial and temporal variability of the major and trace elements of Ganga river water in epirhithron,metarhithron and hyporhithron zone belonging to Himalayan *** samples from nineteen monitoring locations were collected in pre-monsoon(May-June),monsoon(AugustSeptember)and post-monsoon(December)seasons and subjected to be assessed for 20 elements(Ag,Al,Ba,Cd,Ca,Cr,Cu,Fe,Ga,K,Mn,Mg,Na,Ni,Pb,Sr,Th,U,Zn,and Zr)using ICP-OES(Inductively Coupled Plasma-Optical Emission Spectrometer).Different water pollution indexes such as HPI(Heavy Metal Pollution Index),MI(Metal Index)and PI(Pollution Index)were used to describe current water quality status at each monitoring station under particular classified ecological *** studied stations in hyporhithron zone had the value of Metal Index(MI>1),indicating threshold of ***,the highest values of HPI in hyporhithron zone correspond to poor water quality *** with poor water quality were also found to be contaminated as per the Pollution Index(PI),exhibiting high concentrations for element(Fe).However,the epirhithron and metarhithron zone in Himalayan segment showed excellent water quality mainly contributed from natural *** Analysis(CA)and Principal Component Analysis(PCA)were applied to identify the main influential sources for Ganga river water *** Kriging interpolation method was also applied to prepare spatial distribution map of computed indexes(HPI,MI,and PI).With the help of index of local Moran’s I(LMI),identified spatial clusters and spatial outliers revealed the elevated concentration of most elements in hyporhithr

关键词： Trace elements Spatial variation temporal variation Surface water Ganga River Basin ICP-OES

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

MICROSTRUCTURES AND temporal variation CHARACTERISTICS DURING A SEA FOG EVENT ALONG THE WEST COAST OF THE TAIWAN STRAIT

引用

Journal of Tropical Meteorology 2017年第2期23卷 155-165页

作者：张悦樊曙先张舒婷魏锦成 Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and Technology Chongqing Institute of Meteorological Sciences Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science and Technology Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science and Technology Meteorological Bureau of Xiamen

Synoptic systems and microphysical properties associated with a sea fog event are analyzed based on the measurements of visibility, meteorological elements and fog droplet spectrum from a comprehensive field campaign in Xiamen, Fujian province during spring 2013. The influences of meteorological elements on the microstructures of the sea fog are also discussed. The results showed that the wind speed and direction changed suddenly during the intermittent and disperse phases of the sea fog. Liquid water content, number concentration and average diameter varied obviously in the development, mature and disperse phases of the sea fog. The burst re-enforcement of sea fog was accompanied by explosive broadening of fog droplet spectrum; average diameter, number concentration and liquid water content increased sharply; and background meteorological conditions also changed significantly. The microstructures fluctuated intensely due to changes in turbulence, radiation and meteorological conditions at different stages, including nucleation, condensation, coagulation, and evaporation, as well as the discontinuity of spatial distribution of droplets.

关键词： atmospheric physics sea fog meteorological elements microstructure temporal variation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The effects of temporal variation in soil carbon inputs on resource allocation in an annual plant

引用

Journal of Plant Ecology 2016年第1期9卷 30-39页

作者： Hagai Shemesh Uri Ben-Yosef Stav Livne Ofer Ovadia Department of Environmental Sciences Tel-Hai Academic CollegeUpper Galilee 12208Israel Department of Life Sciences Ben-Gurion University of the NegevPOB 653 Beer Sheva 8410501Israel

Aims Resource allocation in plants can be strongly affected by *** plant–plant interactions,terrestrial plants compete with the soil bacterial community over *** the bacterial communities cannot synthesize their own energy sources,they are dependent on external carbon *** the effect of overall amounts of carbon(added to the soil)on plant performance,the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely *** hypothesize that continuous carbon supply(small temporal variance)will result in a relatively constant bacterial biomass that will effectively compete with plants for *** the other hand,carbon pulses(large temporal variance)are expected to cause oscillations in bacterial biomass,enabling plants temporal escape from competition and possibly enabling increased *** thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive *** also expected this effect to be noticeable only when sufficient nutrients were present in the *** Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils,with or without slow-release fertilizer,subjected to one of the following six carbon treatments:daily(1.5mg glucose),every other day(3mg glucose),4 days(6mg glucose),8 days(12mg glucose),16 days(24mg glucose)and no carbon *** Findings Remarkably,carbon pulses(every 2–16 days)led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated *** with our prediction,these effects were noticeable only when sufficient nutrients were present in the ***,soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant *** interpret this to mean that when the amount of available nutrients is low,these nutrients are

关键词： resource allocation temporal variation soil carbon inputs immobilization microbial loop Triticum

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Precise Positioning Method for Seafloor Geodetic Stations Based on the temporal variation of Sound Speed Structure

引用

Journal of Geodesy and Geoinformation Science 2023年第2期6卷 81-92页

作者： Shuang ZHAO Zhenjie WANG Zhixi NIE Kaifei HE Huimin LIU Zhen SUN Chinese Academy of Surveying and Mapping Beijing 100036China College of Oceanography and Space Informatics China University of Petroleum(East China)Qingdao 266580China Qingdao Institute of Marine Geology China Geological SurveyQingdao 266237China

At present,GNSS-Acoustic(GNSS-A)combined technology is widely used in positioning for seafloor geodetic *** on Sound Velocity Profiles(SVPs)data,the equal gradient acoustic ray-tracing method is applied in high-precision position ***,because of the discreteness of the SVPs used in the forementioned method,it ignores the continuous variation of sound velocity structure in time domain,which worsens the positioning *** this study,the time-domain variation of Sound Speed Structure(SSS)has been considered,and the cubic B-spline function is applied to characterize the perturbed sound *** on the ray-tracing theory,an inversion model of“stepwise iteration&progressive corrections”for both positioning and sound speed information is proposed,which conducts the gradual correction of seafloor geodetic station coordinates and disturbed sound *** practical data was used to test the effectiveness of our *** results show that the Root Mean Square(RMS)errors of the residual values of the traditional methods without sound velocity correction,based on quadratic polynomial correction and based on cubic B-spline function correction are 1.43 ms,0.44 ms and 0.21 ms,*** inversion model with sound velocity correction can effectively eliminate the systematic error caused by the change of SSS,and significantly improve the positioning accuracy of the seafloor geodetic stations.

关键词： GNSS-Acoustic sound speed structure temporal variation seafloor positioning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

temporal variation of the Pelagic Copepod Community in Acapulco Bay, México

引用

Open Journal of Marine Science 2016年第1期6卷 40-48页

作者： Agustín A. Rojas-Herrera Juan Violante-González Sergio García-Ibáñez Salvador Villerías-Salinas Giovanni Moreno-Díaz Unidad Académica de Ecología Marina Universidad Autónoma de Guerrero Acapulco México Centro de Investigación y Posgrado en Estudios Socioterritoriales Universidad Autónoma de Guerrero Chilpancingo México

Between September 2009 and April 2010, superficial samples of plankton were collected in Acapulco Bay, using 150-μm mesh net, with the objective of studying the temporal variation in the abundance, species composition of the copepod community, and their relationship with some environmental parameters. Twenty-nine species of four orders were identified: 11 of Calanoida, 4 of Cyclopoida, 3 of Harpacticoida and 11 of Poecilostomatoida. A multivariate analysis (PCA) used to detect association between the abundance of copepod populations, and the environmental conditions through time, indicates a marked effect of the temperature and salinity parameters, on the abundance of the four copepod groups. The calanoids dominated numerically during most of the sampling months. The more important copepods genus were Corycaeus (7 species), andOithona (4 species). Nevertheless that the abundance of all copepod groups was affected temporarily by variations in the environmental conditions, the species composition inside the copepods community remained very stable.

关键词： Copepod Community temporal variation Acapulco Bay Mexico

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

temporal variation of some fundamental constants in the narrow nuclear transition

Temporal variation of some fundamental constants in the narr...

引用

第十三届全国核物理大会暨第八届会员代表大会

作者： Xiao-tao He~1 Zhong-zhou Ren~(1,2) (Department of PhysicS,Nanjing University,Nanjing 210093,China) (Center of Theoretical Nuclear Physics,National Laboratory of Heavy-Ion Accelerator,Lanzhou 730000,China)

The very low energy and narrow width in some nuclear transitions have inspired the idea that these transition might be used to measure the temporal variation of some fundamental physical constants with great enhanced ... 详细信息

关键词： fundamental physical constants nuclear isomer state temporal variation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：