检索结果-南通市图书馆

Spatiotemporal Variation of Riverine Nutrients in a Typical Hilly Watershed in Southeast China Using Multivariate Statistics Tools

引用

Journal of Mountain Science 2015年第4期12卷 983-998页

作者： NIE Xiao-fei LI Heng-peng JIANG Jia-hu DIAO Ya-qin LI Peng-cheng State key laboratory of lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences University of Chinese Academy of Sciences

The water quality of lakes can be degraded by excessive riverine *** water quality generally varies depending on region and season because of the spatiotemporal variations in natural factors and anthropogenic *** water quality measurements of eight water quality variables were analyzed for two years at 16 sites of the Tianmuhu *** variables were examined using hierarchical cluster analysis(HCA) and factor analysis/principal component analysis(FA/PCA) to reveal the spatiotemporal variations in riverine nutrients and to identify their potential *** revealed three geographical groups and three *** drainages comprising towns and large villages were the most polluted, six drainages comprising widely distributed tea plantations and orchards were moderately polluted, and eight drainages without the factors were the least *** river was most polluted in June when the first heavy rain(daily rainfall > 50 mm) occurs after fertilization and the number of rainy days is most(monthly number of rainy days > 20 days).Moderate pollution was observed from October to May, during which morethan 60% of the total nitrogen fertilizer and all of the phosphorus fertilizer are applied to the cropland, the total manure is applied to tea plantations and orchards, and a monthly rainfall ranging from 0 mm to 164 mm *** remaining months were characterized by frequent raining(i.e., number of rainy days per month ranged from 5 to 24) and little use of fertilizers, and were thus least ***/PCA identified that the greatest pollution sources were the runoff from tea plantations and orchards,domestic pollution and the surface runoff from towns and villages, and rural sewage, which had extremely high contributions of riverine nitrogen, phosphorus,and chemical oxygen demand, *** tea plantations and orchards promoted by the agricultural comprehensive development(ACD) were not environmentally *** nitrog

关键词： Nitrogen Phosphorus Chemical oxygen demand Spatial variation Temporal variation Water quality Fertilization Tianmuhu watershed

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

Role of localized phonon vibration in luminescence performance of Pr doped Ba(Mg_(0.28)Zr_(0.16)Ta_(0.56))O_(3)transparent ceramics

引用

Journal of Rare Earths 2022年第11期40卷 1728-1733,I0003页

作者： Zihao Wang Zicheng Wen Fei Tang Kangzhen Tian Chuandong Zuo Lizhen Zhang Jiangsu key laboratory of Advanced Laser Materials and Devices School of Physics and Electronic EngineeringJiangsu Normal UniversityXuzhou 221116China Songshan lake Materials laboratory.Dongguan 523808 China

Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg_(0.28)Zr_(0.16)Ta_(0.56))O_(3)transparent ceramic *** refinement of X-ray diffraction pattern was carried out to reveal the lattice parameters and crystal structural *** the blue-light excitation ofλ=473 nm,the phosphor exhibits a sharp intense red emission centered at645 nm,accompanied by several other weak *** evolution with temperature shows a significant luminescence quenching behavior,and the underlying multi-phonon interaction with optical center is revealed by proposing an unprecedent theoretical calculation *** a phonon effect is further confirmed from the red-shift of peak position with temperature,and the involved phonon energy of50.7 meV is determined from Raman scattering *** interestingly,the fitted results of transient-state PL spectra show a fluctuation of luminescence lifetime at various temperatures,further indicating a significant effect of phonon vibration in the system.

关键词： Luminescence quenching Phonon vibration Oxygen-assisted sintering PBMZT transparent ceramics Rare earths

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

Geochronology and geochemistry of lithium-rich tuffs in the Sichuan basin,western Yangtze:Implication for the magmatic origin and final closure of eastern Paleo-Tethys

引用

Geoscience Frontiers 2023年第1期14卷 272-285页

作者： Yuan Peng Mianping Zheng Yongsheng Zhang Enyuan Xing Baoling Gui Fanfan Zuo MNR key laboratory of Saline lake Resources and Environments Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China

The felsic volcanogenic tuffs named"green-bean rocks"(GBRs),characterized by a green or yellowish green color,are widely distributed in the western Yangtze platform and have a high lithium content(286-957 ppm).This paper studies the ages,origin and tectonic setting of the GBRs in the Sichuan basin on the western margin of the Yangtze platform through the whole-rock geochemistry and zircon trace elements by using U-Pb dating and Hf-O *** GBR samples from the Quxian and Beibei sections yielded zircon U-Pb ages of 245.5±1.8 Ma and 244.8±2.2 *** samples can be used as the isochronous stratigraphic marker of the Early-Middle Triassic boundary(EMTB)for regional *** whole-rock and zircon geochemistry,and zircon Hf-O isotopes exhibited S-type geochemical affinities with high positiveδ^(18)0 values(9.28‰-11.98‰),low negativeε_(Hf)(t)values(-13.87 to-6.79),and T_(DM)^(2)ages of 2150-1703 Ma,indicating that the lithium-rich GBRs were generated by the remelting of the pre-existing ancient Paleoproterozoic layer without mantle source contamination in the arcrelated/orogenic tectonic *** results of this study demonstrate that the lithium-rich GBRs in the western Yangtze platform were derived from arc volcanic eruptions along the Sanjiang orogen,triggered by the closure of the eastern Paleo-Tethys Ocean and the syn-collision between the continental Indochina and Yangtze blocks at ca.247 *** was marked by a major shift from I-type magmas with intermediateε_(Hf)(t)values to S-type magmas with low negativeε_(Hf)(t)***,our results provide new insights into the origin of the GBRs and decodes the closure of the eastern Paleo-Tethys.

关键词： Green-bean rock Lithium-rich Sichuan basin Western Yangtze platform Magmatic source Eastern Paleo-Tethys

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

Source Analysis of Lithium Deposit in Dong-Xi-Taijinaier Salt lake of Qaidam Basin,Qinghai-Tibet Plateau

引用

Journal of Earth Science 2023年第4期34卷 1083-1094页

作者： Jibin Han Hongchen Jiang Jiubo Liu Jianxin Xu Wenhua Han Haiyun Zhang key laboratory of Comprehensive and Highly Efficient Utilization of Salt lake Resources Qinghai Provincial Key Laboratory of Geology and Environment of Salt LakesQinghai Institute of Salt LakesChinese Academy of SciencesXining 810008China State key laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China Qinghai Provincial key laboratory of Exploration Research of Salt lake Resources in Qaidam Basin Qaidam Comprehensive Geological and Mineral Exploration Institute of Qinghai ProvinceGolmud 816099China

The Dong-Xi-Taijinaier Salt lake(DXTSL) of Qaidam Basin is known as one of rich lithium reserves in ***,the source of lithium deposits in this region remains *** hydrochemistry and lithium isotopes(δ7Li) of water and solid samples along the Nalenggele River catchment were studied in combination with rock leaching *** results showed the hot springs in the upstream contained high content of lithium and ratio of Li × 1 000/total dissolved solids(1.5–3.5),but the lower δ7Li values(4.33‰–11.59‰),meaning that it is one important lithium *** leaching experiments by the rich-lithium volcanic rocks(average content of 474.7 mg/kg) showed that under temperature of 20–80 ℃ and long time duration(24–96 h),the concentration of lithium released by leaching of the sampled volcanic rocks increased from 0.58 to 1.49 mg/L,with the leaching rate decreasing from 0.024 to 0.015 mg/(L·h) and the corresponding lithium release rate increasing from 29% to 74%.Calculation based on water-salt balance showed that the total amount of lithium contribution from hydrothermal fluids and volcanic rock weathering is about 4.99 and 0.29 Mt since 13.1 ka,***,hot springs and leaching of volcanic rocks are main contributors to lithium deposit in DXTSL.

关键词： hydrothermal supplement volcanic rock lithium source 'Li isotope Dong-Xi-Taijinaier Saltlake.

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

Effects of Water-table Depth and Soil Moisture on Plant Biomass, Diversity, and Distribution at a Seasonally Flooded Wetland of Poyang lake, China

引用

Chinese Geographical Science 2015年第6期25卷 739-756页

作者： XU Xiuli ZHANG Qi TAN Zhiqiang LI Yunliang WANG Xiaolong key laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and Limnology Chinese Academy of Sciences University of Chinese Academy of Sciences key laboratory of Poyang lake Wetland and Watershed Research Ministry of Education Jiangxi Normal University

Hydrological regime has been widely recognized as one of the major forces determining vegetation distribution in seasonally flooded wetland. Poyang lake, the largest freshwater lake in China, has been encountering dramatic changes in hydrological conditions in last decade, which greatly influenced the wetland vegetations. To explore the relationships between hydrology and vegetation distri- bution, water-table depth, soil moisture, species composition, diversity and biomass were measured at a seasonally flooded wetland section at Wucheng National Nature Reserve. Three plant communities, Artemisia capillaris, Phragmites australis and Carex cineras- cens communities, were examined which are zonally distributed from upland to lakeshore with decreasing elevation. Canonical corre- spondence analysis （CCA）, spearmen correlation and logistic regression were adopted to analyze the relationships between vegetation characteristics and hydrological variables of water-table depth and soil moisture. Results show that significant hydrological gradient exist along the wetland transect. Water-table demonstrates a seasonal variation and is consistently deepest in A. capillaris community （ranging from q）.5 m above ground to ＋10.3 m below ground）, intermediate in P. australis community （-2.6 m to ＋7.8 m） and shallow- est in C. cinerascens community （-4.5 m to ＋6.1 m）. Soil moisture is lowest and most variable in A. capillaris community, highest and least variable in P. australis community, and intermediate and moderate variable in C. cinerascens community. The CCA ordination indicated that variables of water-table depth and soil moisture are strongly related to community distribution, which explained 81.7% of the vegetation variations. Species diversity indices are significantly positively correlated with soil moisture and negatively correlated with moisture variability, while above- and belowground biomass are positively correlated with moisture. Above- and belowground biomass presen

关键词： water-table depth soil moisture species diversity biomass Gaussian model Poyang lake wetland

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

Spatial changes and driving factors of lake water quality in Inner Mongolia, China

引用

Journal of Arid Land 2023年第2期15卷 164-179页

作者： REN Xiaohui YU Ruihong LIU Xinyu SUN Heyang GENG Yue QI Zhen ZHANG Zhuangzhuang LI Xiangwei WANG Jun ZHU Penghang GUO Zhiwei WANG Lixin XU Jifei Inner Mongolia key laboratory of River and lake Ecology School of Ecology and EnvironmentInner Mongolia UniversityHohhot 010021China key laboratory of Mongolian Plateau Ecology and Resource Utilization Ministry of EducationHohhot 010021China

lakes play important roles in sustaining the ecosystem and economic development in Inner Mongolia Autonomous Region of China,but the spatial patterns and driving mechanisms of water quality in lakes so far remain *** study aimed to identify the spatial changes in water quality and the driving factors of seven lakes(Juyanhai lake,Ulansuhai lake,Hongjiannao lake,Daihai lake,Chagannaoer lake,Hulun lake,and Wulannuoer lake)across the longitudinal axis(from the west to the east)of Inner ***-scale research was conducted using the comprehensive trophic level index(TLI(Σ)),multivariate statistics,and spatial analysis *** results showed that most lakes in Inner Mongolia were weakly *** dissolved solids and salinity of lake water showed obvious zonation *** and phosphorus were identified as the main pollutants in lakes,with high average concentrations of total nitrogen and total phosphorus being of 4.05 and 0.21 mg/L,*** values of TLI(Σ)ranged from 49.14 to 71.77,indicating varying degrees of lake eutrophication,and phosphorus was the main driver of lake *** lakes of Inner Mongolia could be categorized into lakes to the west of Daihai lake and lakes to the east of Daihai lake in terms of salinity and TLI(Σ).The salinity levels of lakes to the west of Daihai lake exceeded those of lakes to the east of Daihai lake,whereas the opposite trend was observed for lake trophic *** intensity and mode of anthropogenic activities were the driving factors of the spatial patterns of lake water *** is recommended to control the impact of anthropogenic activities on the water quality of lakes in Inner Mongolia to improve lake ecological *** findings provide a more thorough understanding of the driving mechanism of the spatial patterns of water quality in lakes of Inner Mongolia,which can be used to develop strategies for lake ecosystem protection and water resources management i

关键词： salinity lake eutrophication lake water quality comprehensive trophic level index anthropogenic activities Daihai lake Inner Mongolia

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

Controlling cyanobacterial blooms by managing nutrient ratio and limitation in a large hypereutrophic lake: lake Taihu, China

引用

Journal of Environmental Sciences 2015年第1期27卷 80-86页

作者： Jianrong Ma Boqiang Qin Pan Wu Jian Zhou Cheng Niu Jianming Deng Hailin Niu State key laboratory of lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences key laboratory of Reservoir Aquatic Environment Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences College of Ecological and environmental Engineering Qinghai University

Excessive nitrogen（N） and phosphorus（P） loading of aquatic ecosystems is a leading cause of eutrophication and harmful algal blooms worldwide, and reducing nutrient levels in water has been a primary management objective. To provide a rational protection strategy and predict future trends of eutrophication in eutrophic lakes, we need to understand the relationships between nutrient ratios and nutrient limitations. We conducted a set of outdoor bioassays at the shore of lake Taihu. It showed that N only additions induced phytoplankton growth but adding only P did not. Combined N plus P additions promoted higher phytoplankton biomass than N only additions, which suggested that both N and P were deficient for maximum phytoplankton growth in this lake（TN：TP = 18.9）. When nutrients are present at less than 7.75–13.95 mg/L TN and 0.41–0.74 mg/L TP, the deficiency of either N or P or both limits the growth of phytoplankton. N limitation then takes place when the TN：TP ratio is less than 21.5–24.7（TDN：TDP was 34.2–44.3）, and P limitation occurs above this. Therefore, according to this ratio, controlling N when N limitation exists and controlling P when P deficiency is present will prevent algal blooms effectively in the short term. But for the long term, a persistent dual nutrient（N and P） management strategy is necessary.

关键词： Eutrophication Cyanobacterial blooms Nutrient ratio Nitrogen Phosphorus Limitation

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

Variation in Short-term Temperature Fluctuations Across China During the Past 60 Years

引用

Chinese Geographical Science 2022年第4期32卷 563-579页

作者： HE Yunchuan DENG Jianming ZHANG Yunlin DING Yanqing QIN Boqiang Taihu lake laboratory Ecosystem Research Station State Key Laboratory of Lake Science and EnvironmentNanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China School of Resource and Geosciences China University of Mining and TechnologyXuzhou 221116China

Short-term temperature fluctuations(STFs),including amplitude and frequency fluctuations,are one of the main features of weather and play vital roles in determining the type of ecosystem *** temperature fluctuations at different time scales have been extensively discussed,the research on week-scale STFs is *** this study,we developed a method,that can quantify the amplitude and frequency of STFs by the thresholds from all *** used this method to quantify the amplitude and frequency of the 7-d STFs from 1951 to 2019 across *** results indicate that the amplitude of the STF was much higher in the eastern part of China than in the western part,while the frequency of the STF was higher in the middle part than in the southern and northern parts;further-more,the STF was highly dependent on internal factors such as *** long-term STF mainly showed a decreasing trend before 1990,which implies that temperature became increasingly stable from the 1950s to the *** main influencing factors were related to topography since the trends were relatively consistent in space.A case study in Taihu lake showed that an unstable STF in winter and summer resulted in a smaller bloom area in the following spring and *** method could eliminate seasonal effects and is capable of analyzing STFs at scales ranging from days to *** of the amplitude and frequency also make the STF indicators more ***,the STF increased significantly across most of China after 1990,which implies that temperature is becoming increasingly *** drivers of these STFs are related to human impacts since the trends are different in space.

关键词： short-term temperature fluctuation altitude effect global warming climate change China

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

A review of rock macro-indentation:Theories,experiments,simulations,and applications

引用

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2351-2374页

作者： Weiqiang Xie Xiaoli Liu Xiaoping Zhang Xinmei Yang Xiaoxiong Zhou State key laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing100084China Yunlong lake laboratory of Deep Underground Science and Engineering Xuzhou221116China State key laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China

Rock macro-indentation plays a fundamental role in mechanical rock breaking for various rock engineering application,such as drilling,tunneling,cutting,and *** the past decades,extensive research has been conducted to understand the indentation mechanisms and responses through various *** review aims to provide an overview of the current status and recent advancements in theories,experiments,numerical simulations,and applications of macro-indentation in rock *** starts with elaborating on the mechanisms of macro-indentation,followed by a discussion of the merits and limitations of commonly used *** factors and their effects on indentation test results are then *** numerical simulation methods for rock macro-indentation are highlighted,along with their advantages and ***,the applications of indentation tests and indentation indices in characterizing rock properties are *** reveals that compression-tension,compression-shear,and composite models are widely employed in rock *** the compression-tension model is straightforward to use,it may overlook the anisotropic properties of *** the other hand,the composite model provides a more comprehensive description of rock indentation but requires complex ***,factors,such as indentation rate,indenter geometry,rock type,specimen size,and confining pressure,can significantly influence the indentation *** methods for macro-indentation encompass continuous medium,discontinuous medium,and continuous-discontinuous medium methods,with selection based on their differences in ***,rock macro-indentation can be practically applied to mining engineering,tunneling engineering,and petroleum drilling *** indices serve as valuable tools for characterizing rock strength,brittleness,and *** review sheds light on the development of rock macro-inde

关键词： Rock macro-indentation Indentation test Indentation indices Mechanism Rock breaking

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

Atmospheric correction of ocean color imagery over turbid coastal waters using active and passive remote sensing

引用

Chinese Journal of Oceanology and Limnology 2009年第1期27卷 124-128页

作者：田礼乔陈晓玲张亭禄龚威陈莉琼陆建忠赵羲张伟于之锋 State key laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University The key Lab. of Poyang lake Environment and Resource Utilization Ministry of Education Nanchang University The key laboratory of Poyang lake Wetland and Watershed Research Ministry of Education Jiangxi Normal University laboratory of Ocean Remote Sensing Ministry of Education Ocean Remote Sensing Institute Ocean University of China

This paper demonstrates an atmospheric correction method to process MODIS/Aqua (Moderate-resolution Imaging Spectroradiometer) ocean color imagery over turbid coastal waters with the aid of concurrent CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) aerosol data, assuming that there exists "nonturbid" water in the study area where MODIS aerosol optical properties can be retrieved accurately. Aerosol properties from CALIOP measurements were obtained and related to those from MODIS. This relationship, combined with CALIOP aerosol data, was extended to turbid water to derive MODIS aerosol properties, where atmospheric correction using MODIS data alone often fails. By combining MODIS and CALIOP data, aerosol signals were separated from the total signals at the satellite level, and water-leaving radiances in turbid waters were subsequently derived. This method was tested on several MODIS/Aqua ocean color images over South China turbid waters. Comparison with field data shows that this method was effective in reducing the errors in the retrieved water-leaving radiance values to some extent. In the Zhujiang (Pearl) River Estuary, this method did not overestimate the aerosol effects as severely, and provided far fewer negative water-leaving radiance values than the NASA (National Aeronautics and Space Administration) default methods that used MODIS data alone.

关键词： Ocean color remote sensing atmospheric correction turbid coastal waters CALIOP MODIS

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

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：