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Six national-scale, or near national-scale, geochemical data sets for soils or stream sediments exist for the United States. The earliest of these, here termed the ‘Shacklette’ data set, was generated by a U.S. Geological Survey (USGS) project conducted from 1961 to 1975. This project used soil collected from a depth of about 20 cm as the sampling medium at 1323 sites throughout the conterminous U.S. The National Uranium Resource Evaluation Hydrogeochemical and Stream Sediment Reconnaissance (NURE-HSSR) Program of the U.S. Department of Energy was conducted from 1975 to 1984 and collected either stream sediments, lake sediments, or soils at more than 378,000 sites in both the conterminous U.S. and Alaska. The sampled area represented about 65% of the nation. The Natural Resources Conservation Service (NRCS), from 1978 to 1982, collected samples from multiple soil horizons at sites within the major crop-growing regions of the conterminous U.S. This data set contains analyses of more than 3000 samples. The National Geochemical Survey, a USGS project conducted from 1997 to 2009, used a subset of the NURE-HSSR archival samples as its starting point and then collected primarily stream sediments, with occasional soils, in the parts of the U.S. not covered by the NURE-HSSR Program. This data set contains chemical analyses for more than 70,000 samples. The USGS, in collaboration with the Mexican Geological Survey and the Geological Survey of Canada, initiated soil sampling for the North American Soil Geochemical Landscapes Project in 2007. Sampling of three horizons or depths at more than 4800 sites in the U.S. was completed in 2010, and chemical analyses are currently ongoing. The NRCS initiated a project in the 1990s to analyze the various soil horizons from selected pedons throughout the U.S. This data set currently contains data from more than 1400 sites. This paper (1) discusses each data set in terms of its purpose, sample collection protocols, and analytical methods; and (2) evaluates each data set in terms of its appropriateness as a national-scale geochemical database and its usefulness for national-scale geochemical mapping. 相似文献
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《国际地震动态》编辑部 《国际地震动态》2009,(10):40-40
中国地震台网中心和美国地质调查局（USGS）公布的该地震的参数如下：
1 中国地震台网中心
发震时间：北京时间2009年9月30日18时16分; 相似文献
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引言
美国国家科学基金会（NSF）、美国地质调查局（USGS）和美国国家航空与航天局（NASA）在2001年联合发起了地球透镜（Earthscope）计划,该计划旨在通过分布式、多用途仪器和观测台网的组合使用,来加深对北美大陆结构、演化和动力学特征的理解。 相似文献
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机载激光雷达已经成为世界陆地测绘的主要手段之一.但是,目前中国还缺乏全国范围内统一、协调的机载激光雷达采集数据,导致数据重复采集、资金浪费或大片区域缺乏高质量数据.美国和欧洲一些国家已经开展了全国范围的机载激光雷达数据采集工作,其中的代表是美国三维高程计划(3D Elevation Program,3DEP).保守估计... 相似文献
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美国地质调查局(USGS)不同时期财政预算拨款数额和结构的变化,不仅反映其工作重点的变化,更深层次是反映出USGS围绕国家重大需求做出的战略调整。2015年USGS优先项目预算提案中增资内容主要包括生态环境修复、水资源管理、与非常规天然气开发相关的水力压裂影响研究、数据更新与制图、可持续能源开发等几个方面。在分析近20年来美国地质调查局重点工作变化的基础上,提出了中国地质调查工作应紧密围绕我国经济新常态形势下的国家需求,以生态文明建设为核心,加强对清洁能源、矿产和地下水资源的调查力度,为保障经济社会发展需求服务。 相似文献
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日前,美国地质调查局公布了2010财年预算报告：预算总数为10.978亿美元,与2009财年已批准拨款10.438亿美元相比,增加了5400万美元,工作重点较以往更加倾向于环境和生态保护方面。 相似文献