Predicting quantiles of water quality from catchment characteristics     

Danlu Guo  Shuci Liu  Dhananjay Singh  Andrew W. Western 《水文研究》2021,35(1):e13996

Water quality is often highly variable both in space and time, which poses challenges for modelling the more extreme concentrations. This study developed an alternative approach to predicting water quality quantiles at individual locations. We focused on river water quality data that were collected over 25 years, at 102 catchments across the State of Victoria, Australia. We analysed and modelled spatial patterns of the 10th, 25th, 50th, 75th and 90th percentiles of the concentrations of sediments, nutrients and salt, with six common constituents: total suspended solids (TSS), total phosphorus (TP), filterable reactive phosphorus (FRP), total Kjeldahl nitrogen (TKN), nitrate-nitrite (NO_x), and electrical conductivity (EC). To predict the spatial variation of each quantile for each constituent, we developed statistical regression models and exhaustively searched through 50 catchment characteristics to identify the best set of predictors for that quantile. The models predict the spatial variation in individual quantiles of TSS, TKN and EC well (66%–96% spatial variation explained), while those for TP, FRP and NO_x have lower performance (37%–73% spatial variation explained). The most common factors that influence the spatial variations of the different constituents and quantiles are: annual temperature, percentage of cropping land area in catchment and channel slope. The statistical models developed can be used to predict how low- and high-concentration quantiles change with landscape characteristics, and thus provide a useful tool for catchment managers to inform planning and policy making with changing climate and land use conditions.  相似文献   

自然资源一体化政务服务系统及数据融合建设——以南京为例     

陈波  崔蓓  丁鑫 《测绘通报》2020,(12):75-78

自然资源部制定的信息化建设总体方案中，要求构建“互联网+自然资源政务服务”应用体系，实现“服务事项标准统一、整体联动、业务协同，自然资源政务服务和共享开放能力全面提高”。一体化政务服务系统作为政务服务应用体系的重点建设内容，也是落实自然资源管理“两统一”职责的重要支撑，如何整合各类数据资源、发挥系统作用，成为亟待研究的问题。本文在分析自然资源业务管理需求后，提出了一体化政务服务系统及数据融合的建设思路。  相似文献   

Smectite formation in metalliferous sediments near the East Pacific Rise at 13°N   总被引：1，自引：0，他引：1  

荣坤波  曾志刚  殷学博  陈帅  王晓媛  齐海燕  马瑶 《海洋学报(英文版)》2018,37(9):67-81

A 43 cm long E271 sediment core collected near the East Pacific Rise(EPR) at 13°N were studied to investigate the origin of smectite for understanding better the geochemical behavior of hydrothermal material after deposition.E271 sediments are typical metalliferous sediments. After removal of organic matter, carbonate, biogenic opal,and Fe-Mn oxide by a series of chemical procedures, clay minerals(2 μm) were investigated by X-ray diffraction,chemical analysis and Si isotope analysis. Due to the influence of seafloor hydrothermal activity and close to continent, the sources of clay minerals are complex. Illite, chlorite and kaolinite are suggested to be transported from either North or Central America by rivers or winds, but smectite is authigenic. It is enriched in iron, and its contents are highest in clay minerals. Data show that smectite is most likely formed by the reaction of hydrothermal Fe-oxyhydroxide with silica and seawater in metalliferous sediments. The Si that participates in this reaction may be derived from siliceous microfossils(diatoms or radiolarians), hydrothermal fluids, or detrital mineral phases. And their δ30 Si values are higher than those of authigenic smectites, which implies that a Si isotope fractionation occurs during the formation because of the selective absorption of light Si isotopes onto Feoxyhydroxides. Sm/Fe mass ratios(a proxy for overall REE/Fe ratio) in E271 clay minerals are lower than those in metalliferous sediments, as well as distal hydrothermal plume particles and terrigenous clay minerals. This result suggests that some REE are lost during the smectite formation, perhaps because their large ionic radii of REE scavenged by Fe-oxyhydroxides preclude substitution in either tetrahedral or octahedral lattice sites of this mineral structure, which decreases the value of metalliferous sediments as a potential resource for REE.  相似文献   

基于SODA资料的南海表层风能输入的空间分布与长期趋势研究     

杨倩  崔超然  张宇  刘志宇  管玉平  黄瑞新 《热带海洋学报》2018,37(6):41-48

海面风不仅是驱动上层海洋运动的主要动力, 其能量也是维持海洋表层流动的主要机械能来源。为了分析南海表层流风能输入的变化, 用SODA(Simple Ocean Data Assimilation)(1901—2010)资料估算了风向南海表层流(表层地转流+表层非地转流)的能量输入。结果表明, 风向南海表层流、表层地转流和表层非地转流输入的能量总体均呈减少趋势, 110年间分别减小了约56%、65%和49%。导致风能输入减小的最主要因素是风应力的减弱(减小了35%)。由于南海受季风系统的控制, 风向表层流及其各成分输入的能量呈现出显著的季节性变化。冬季风能输入最强, 高值区位于南海西部及北部区域, 呈一个显著的“回力镖”状结构。这些结果对深入认识南海环流具有理论意义。  相似文献   

日照市土壤地球化学元素分布规律及成因探讨          下载免费PDF全文

庞绪贵  宋娟娟  代杰瑞  喻超  张华平  陈磊  任天龙  王红晋 《山东国土资源》2018,34(4)

在日照市开展多目标区域地球化学调查，获取了表层土壤和深层土壤地球化学数据，通过对获得的地球化学参数进行统计分析，确定了日照市土壤地球化学基准值和背景值，认为日照市除部分元素或指标外，大部分元素或指标土壤地球化学基准值和背景值与全省土壤地球化学基准值和背景值接近。研究发现，日照市As，Cd，Cr，Cu，Hg，Ni，Pb，Zn等8种重金属元素背景值含量低于国家土壤环境质量标准的土壤一级标准限值，日照市土壤质量基本保持自然背景水平；而受工业化生产和城市化建设等后期人为活动影响，日照市表层土壤中Cd，C，Hg，N，P，S，Se，Corg等元素或指标出现明显富集，应引起重视。  相似文献   

自然资源全要素自适应野外调查框架设计     

刘立  刘娟  陈宏宇  李维庆 《测绘通报》2020,(1):107

针对自然资源全要素调查工作中分类标准不同、调查口径不同、调查方法不同，造成的各部门调查软件平台重复开发建设和调查数据结果地理信息特征表达不清晰等问题，本文结合自然资源全要素野外调查工作的实际需要，以山水林田湖草生命共同体为统一对象，构建了自然资源语义化特征模型，提出了表征不同自然资源类型的自适应野外调查方法，实现了灵活性高、性能优异的自然资源调查技术平台，形成了统一的自然资源全要素野外调查框架，可以有效提升多门类自然资源基础调查、专业调查、动态调查的能力与水平，为自然资源治理能力现代化提供了可靠技术保障。  相似文献   

基于MODIS数据的湖北省地级以上城市城区地表温度变化分析     

李韶颖  车风  邵军  陈涛  周婧娟 《测绘与空间地理信息》2020,(2):76-78

基于MODIS数据,以湖北省地级以上城市城区为研究对象,通过对湖北省13个地级以上城市城区边界矢量数据与地表温度因子进行套合处理,采用叠置分析方法对2000、2015、2017年湖北省地级以上城市城区的地表温度进行统计,并分析城镇化建设对城区地表温度产生的影响。  相似文献   

贵州夜郎湖表层水体地球化学昼夜变化及其影响因素     

王家录  任娟  王勇  李维杰  娄昭  陈佳 《热带地理》2020,40(2):335-345

为探究岩溶水库水文地球化学行为过程,对贵州普定夜郎湖表层水体进行了为期3 d的高分辨率昼夜监测。结果表明：1）多变的天气和水文条件叠加导致水体离子指标昼夜变化不显著,规律性较差。而水温、DO、pH值、SpC、SIc、pCO₂等常规理化指标受水温变化和生物作用表现出明显的昼夜波动。2）利用亨利常数和主成分分析,得到温度变化、生物作用、人类活动、水库的蓄水与放水对夜郎湖水库水文地球化学特征变化的贡献率分别为21.66%、17.28%、14.08%和10.22%,说明作用于水库水文地球化学行为的因子具有多元性。3）δ ¹⁸O表现出与DO一致的波动趋势,即白天上升,晚上下降,反映在短时间尺度上,氢氧稳定同位素变化受控于生物过程（主要是呼吸作用过程）;而对比水库水体和大气降水的d-excess（d值）发现,水库水体的d值（8.21‰）显著偏低于当地大气降水的d值（9.64‰）,说明在长时间尺度上,主要受蒸发效应引起的不平衡分馏影响。  相似文献   

On the orthogonality of surface wave eigenfunctions in cylindrical coordinates     

M. G. Bostock 《Geophysical Journal International》1990,103(3):763-767

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Characteristics of Spatial and Temporal Variations of Monthly Mean Surface Air Temperature over Qinghai-Tibet Plateau   总被引：1，自引：0，他引：1  

ZHANG Qianggong KANG Shichang YAN Yuping 《中国地理科学(英文版)》2006,16(4):351-358

1 Introduction The Qinghai-Tibet Plateau, known as the highest plateau with the most complex topography in the world, covers an area of more than 200km2, with a mean elevation of more than 4000m a.s.l. (Ye and Gao, 1979). Surrounded by the Earth’s highest mountains, such as the Himalayas, Pamir, Kunlun Mountains, the plateau plays a significant role in climate change in China even in the world, thus attracted great attention of researchers. Up to now, many achievements have been gained by…  相似文献