| 1 | History and evaluation of national-scale geochemical data sets for the United States显示文摘六国家规模,或近国家规模,为土壤的 geochemical 数据集合或溪流沉积为美国存在。这些最早,这里称为 Shacklette 数据集合,被从 1961 ~ 1975 进行的一个美国地质的调查(USGS ) 工程产生。这个工程使用了在整个有共同边界的美国在 1323 个地点作为采样媒介从大约 20 厘米的深度收集的土壤美国能源部的国家的铀资源评估 Hydrogeochemical 和流沉积侦察( NURE-HSSR )程序从 1975~1984 被进行并且收集了任何一个流沉积,在在有共同边界的美国和阿拉斯加的超过 378,000 个地点的湖沉积,或土壤。取样的区域代表了大约 65% 国家。从 1978 ~ 1982,自然资源保存服务(NRCS ) 在这个数据设置了的有共同边界的美国的主要成长庄稼的区域以内在地点从多重土壤地平线收集了样品包含超过 3000 件样品的分析。国家 Geochemical 调查,从 1997 ~ 2009 进行,把 NURE-HSSR 档案的样品的一个子集用作它的起点然后首先收集了溪流沉积的一个 USGS 工程与偶尔的土壤,在没被 NURE-HSSR 盖住的美国的部分编程序。这个数据集合为超过 70,000 件样品包含化学分析。与墨西哥地质的调查和加拿大的地质的调查合作, USGS 在 2007 为北美的土壤 Geochemical 风景工程开始了土壤采样。在在美国的超过 4800 个地点的三根地平线或深度的采样在 2010 被完成,并且化学分析当前是进行中的。NRCS 在 1990 年代开始了一个工程全部从选择 pedons 分析各种各样的土壤地平线这个数据设置了的美国当前从超过 1400 个地点包含数据。这份报纸(1 ) 以它的目的,样品收集协议,和分析方法讨论每个数据集合;并且(2 ) 为印射的国家规模的 geochemical 作为一个国家规模的 geochemical 数据库和它的实用性以它的适当评估每个数据集合。 | David B.Smith Steven M.Smith John D.Horton | 2013 | Geoscience Frontiers2013，4，2： | 8 |
| 2 | History and Progress of the North American Soil Geochemical Landscapes Project,2001-2010显示文摘In 2007,the U.S.Geological Survey,the Geological Survey of Canada,and the Mexican Geological Survey initiated a low-density(1 site per 1600 km2,13323 sites) geochemical and mineralogical survey of North American soils(North American Soil Geochemical Landscapes Project).Sampling and analytical protocols were developed at a series of workshops in 2003-2004 and pilot studies were conducted from 2004-2007.The ideal sampling protocol at each site includes a sample from 0-5 cm depth,a composite of the soil A horizon,and a sample from the soil C horizon.The <2-mm fraction of each sample is analyzed for Al,Ca,Fe,K,Mg,Na,S,Ti,Ag,Ba,Be,Bi,Cd,Ce,Co,Cr,Cs,Cu,Ga,In,La,Li,Mn,Mo,Nb,Ni,P,Pb,Rb,Sb,Sc,Sn,Sr,Te,Th,Tl,U,V,W,Y,and Zn by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry following a near-total digestion in a mixture of HCl,HNO3,HClO4,and HF.Separate methods are used for As,Hg,Se,and total C on this same size fraction.The major mineralogical components are determined by a quantitative X-ray diffraction method.Sampling in the conterminous U.S.was completed in 2010(c.4800 sites) with chemical and mineralogical analysis currently underway.In Mexico,approximately 66% of the sampling(871 sites) had been done by the end of 2010 with completion expected in 2012.After completing sampling in the Maritime provinces and portions of other provinces(472 sites,7.6% of the total),Canada withdrew from the project in 2010.Preliminary results for a swath from the central U.S.to Florida clearly show the effects of soil parent material and climate on the chemical and mineralogical composition of soils.A sample archive will be established and made available for future investigations. | David B.Smith William F.Cannon Laurel G.Woodruff Francisco Moreira Rivera Andrew N.Rencz Robert G.Garrett | 2012 | 地学前缘2012，19，3： | 7 |
| 3 | The IUGS/IAGC Task Group on Global Geochemical Baselines显示文摘The Task Group on Global Geochemical Baselines,operating under the auspices of both the International Union of Geological Sciences(IUGS) and the International Association of Geochemistry(IAGC),has the long-term goal of establishing a global geochemical database to document the concentration and distribution of chemical elements in the Earth's surface or near-surface environment.The database and accompanying element distribution maps represent a geochemical baseline against which future human-induced or natural changes to the chemistry of the land surface may be recognized and quantified.In order to accomplish this long-term goal,the activities of the Task Group include:(1) developing partnerships with countries conducting broad-scale geochemical mapping studies;(2) providing consultation and training in the form of workshops and short courses;(3) organizing periodic international symposia to foster communication among the geochemical mapping community;(4) developing criteria for certifying those projects whose data are acceptable in a global geochemical database;(5) acting as a repository for data collected by those projects meeting the criteria for standardization;(6) preparing complete metadata for the certified projects;and(7) preparing,ultimately,a global geochemical database.This paper summarizes the history and accomplishments of the Task Group since its first predecessor project was established in 1988. | David B.Smith Shaun Reeder Alecos Demetriades | 2012 | 地学前缘2012，19，3： | 5 |
您所在的机构暂未开通此部分的功能，请联系管理员