Institution
United States Geological Survey
Government•Reston, Virginia, United States•
About: United States Geological Survey is a government organization based out in Reston, Virginia, United States. It is known for research contribution in the topics: Population & Groundwater. The organization has 17899 authors who have published 51097 publications receiving 2479125 citations. The organization is also known as: USGS & US Geological Survey.
Topics: Population, Groundwater, Volcano, Aquifer, Fault (geology)
Papers published on a yearly basis
Papers
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Ohio State University1, Pennsylvania State University2, University of Colorado Boulder3, University of Massachusetts Amherst4, United States Geological Survey5, Old Dominion University6, Geological Survey of Canada7, University of Copenhagen8, Cooperative Institute for Research in Environmental Sciences9, Stockholm University10, McGill University11, James Madison University12, British Antarctic Survey13
TL;DR: In this article, the history of Arctic sea-ice conditions through the geologic past is investigated using proxy records from the Arctic Ocean floor and from the surrounding coasts, which indicate that sea ice became a feature of the Arctic by 47-Ma, following a pronounced decline in atmospheric pCO2 after the Paleocene-Eocene Thermal Optimum, and consistently covered at least part of the arctic Ocean for no less than the last 13-14 million years.
382 citations
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TL;DR: In this paper, the compositional differences between fulvic acids and humic acids from soil, stream and marine environments by five different methods (1H and 13C NMR spectroscopy, 14C age and δ13C isotopic analyses, amino acid analyses, pyrolysis-mass spectrometry).
381 citations
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01 Jan 2003TL;DR: The RockJock program as mentioned in this paper is a computer program that determines quantitative mineralogy in powdered samples by comparing the integrated X-ray diffraction (XRD) intensities of individual minerals in complex mixtures to the intensity of an internal standard.
Abstract: RockJock is a computer program that determines quantitative mineralogy in powdered samples by comparing the integrated X-ray diffraction (XRD) intensities of individual minerals in complex mixtures to the intensities of an internal standard. This manual discusses how to prepare and X-ray samples and standards for this type of analysis and describes the operation of the program. Carefully weighed samples containing an internal standard (zincite) are ground in a McCrone mill. Randomly oriented preparations then are X-rayed, and the X-ray data are entered into the RockJock program. Minerals likely to be present in the sample are chosen from a list of standards, and the calculation is begun. The program then automatically fits the sum of stored XRD patterns of standard, pure minerals (the calculated pattern) to the measured pattern by varying the fraction of each standard pattern, using the Solver function in Microsoft Excel to minimize the degree of fit parameter between the calculated and measured pattern. The calculation normally analyses the full pattern (usually 20 to 65 degrees two-theta) to find integrated intensities for the minerals, but it also has the option to carry out an extended clay analysis, in which a smaller region of the XRD pattern (usually 58 to 65 degrees two-theta) is analyzed to find intensities for the clay minerals. Integrated intensities for each mineral then are determined from the proportion of each standard pattern required to give the best fit. These integrated intensities then are compared to the integrated intensity of the internal standard, and the weight percentages of the minerals are calculated. The results are presented as a list of minerals with their corresponding weight percent. To some extent, the quality of the analysis can be checked because each mineral is analyzed independently, and, therefore, the sum of the analysis should approach 100 percent. Also, the method has been shown to give good results with artificial mixtures. The program is easy to use, but does require an understanding of mineralogy, of X-ray diffraction practice, and an elementary knowledge of the Excel program.
381 citations
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TL;DR: The first phase of intensive data collection for the National Water Quality Assessment (NAWQA) was completed during 1993−1995 in 20 major hydrologic basins of the United States as mentioned in this paper.
Abstract: The first phase of intensive data collection for the National Water-Quality Assessment (NAWQA) was completed during 1993−1995 in 20 major hydrologic basins of the United States. Groundwater land-use studies, designed to sample recently recharged groundwater (generally within 10 years) beneath specific land-use and hydrogeologic settings, are a major component of the groundwater quality as sessment for NAWQA. Pesticide results from the 41 land-use studies conducted during 1993−1995 indicate that pesticides were commonly detected in shallow groundwater, having been found at 54.4% of the 1034 sites sampled in agricultural and urban settings across the United States. Pesticide concentrations were generally low, with over 95% of the detections at concentrations less than 1 μg/L. Of the 46 pesticide compounds examined, 39 were detected. The compounds detected most frequently were atrazine (38.2%), deethylatrazine (34.2%), simazine (18.0%), metolachlor (14.6%), and prometon (13.9%). Statistically significant rel...
381 citations
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Lawrence Livermore National Laboratory1, United States Naval Research Laboratory2, United States Geological Survey3, Universities Space Research Association4, California Institute of Technology5, University of Colorado Boulder6, Centre National D'Etudes Spatiales7, RAND Corporation8, University of Hawaii at Manoa9, Brown University10, Stanford University11, Goddard Space Flight Center12, AlliedSignal13, Science Applications International Corporation14, Johns Hopkins University15
TL;DR: In the course of 71 days in lunar orbit, from 19 February to 3 May 1994, the Clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths, enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the Lunar polar regions and the lunar far side.
Abstract: In the course of 71 days in lunar orbit, from 19 February to 3 May 1994, the Clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths. These data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side. In addition, laser-ranging measurements provided the first view of the global topographic figure of the moon. The topography of many ancient impact basins has been measured, and a global map of the thickness of the lunar crust has been derived from the topography and gravity.
381 citations
Authors
Showing all 18026 results
Name | H-index | Papers | Citations |
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Derek R. Lovley | 168 | 582 | 95315 |
Steven Williams | 144 | 1375 | 86712 |
Thomas J. Smith | 140 | 1775 | 113919 |
Jillian F. Banfield | 127 | 562 | 60687 |
Kurunthachalam Kannan | 126 | 820 | 59886 |
J. D. Hansen | 122 | 975 | 76198 |
John P. Giesy | 114 | 1162 | 62790 |
David Pollard | 108 | 438 | 39550 |
Alan Cooper | 108 | 746 | 45772 |
Gordon E. Brown | 100 | 454 | 32152 |
Gerald Schubert | 98 | 614 | 34505 |
Peng Li | 95 | 1548 | 45198 |
Vipin Kumar | 95 | 614 | 59034 |
Susan E. Trumbore | 95 | 337 | 34844 |
Alfred S. McEwen | 92 | 624 | 28730 |