scispace - formally typeset
Search or ask a question
Institution

United States Geological Survey

GovernmentReston, 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.


Papers
More filters
Journal ArticleDOI
TL;DR: Comparison of mass balance and stoichiometric approaches that constrain estimates of denitrification at large scales with point measurements (made using multiple methods), in multiple systems, is likely to propel more improvement in Denitrification methods over the next few years.
Abstract: Denitrification, the reduction of the nitrogen (N) oxides, nitrate (NO3-) and nitrite (NO2-), to the gases nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2), is important to primary production, water quality, and the chemistry and physics of the atmosphere at ecosystem, landscape, regional, and global scales. Unfortunately, this process is very difficult to measure, and existing methods are problematic for different reasons in different places at different times. In this paper, we review the major approaches that have been taken to measure denitrification in terrestrial and aquatic environments and discuss the strengths, weaknesses, and future prospects for the different methods. Methodological approaches covered include (1) acetylene-based methods, (2) 15N tracers, (3) direct N2 quantification, (4) N2:Ar ratio quantification, (5) mass balance approaches, (6) stoichiometric approaches, (7) methods based on stable isotopes, (8) in situ gradients with atmospheric environmental tracers, and (9) molecular approaches. Our review makes it clear that the prospects for improved quantification of denitrification vary greatly in different environments and at different scales. While current methodology allows for the production of accurate estimates of denitrification at scales relevant to water and air quality and ecosystem fertility questions in some systems (e.g., aquatic sediments, well-defined aquifers), methodology for other systems, especially upland terrestrial areas, still needs development. Comparison of mass balance and stoichiometric approaches that constrain estimates of denitrification at large scales with point measurements (made using multiple methods), in multiple systems, is likely to propel more improvement in denitrification methods over the next few years.

874 citations

Journal ArticleDOI
TL;DR: In this paper, the authors classify orogens into retreating and advancing types, based on their kinematic framework and resulting geological character, including the supra-subduction zone forearc, magmatic arc and back-arc components.
Abstract: Accretionary orogens form at intraoceanic and continental margin convergent plate boundaries. They include the supra-subduction zone forearc, magmatic arc and back-arc components. Accretionary orogens can be grouped into retreating and advancing types, based on their kinematic framework and resulting geological character. Retreating orogens (e.g. modern western Pacific) are undergoing long-term extension in response to the site of subduction of the lower plate retreating with respect to the overriding plate and are characterized by back-arc basins. Advancing orogens (e.g. Andes) develop in an environment in which the overriding plate is advancing towards the downgoing plate, resulting in the development of foreland fold and thrust belts and crustal thickening. Cratonization of accretionary orogens occurs during continuing plate convergence and requires transient coupling across the plate boundary with strain concentrated in zones of mechanical and thermal weakening such as the magmatic arc and back-arc region. Potential driving mechanisms for coupling include accretion of buoyant lithosphere (terrane accretion), flat-slab subduction, and rapid absolute upper plate motion overriding the downgoing plate. Accretionary orogens have been active throughout Earth history, extending back until at least 3.2 Ga, and potentially earlier, and provide an important constraint on the initiation of horizontal motion of lithospheric plates on Earth. They have been responsible for major growth of the continental lithosphere through the addition of juvenile magmatic products but are also major sites of consumption and reworking of continental crust through time, through sediment subduction and subduction erosion. It is probable that the rates of crustal growth and destruction are roughly equal, implying that net growth since the Archaean is effectively zero.

874 citations

Journal ArticleDOI
TL;DR: In this paper, a study of U(VI) adsorption by ferrihydrite was conducted over a wide range of U (VI) concentrations, pH, and at two partial pressures of carbon dioxide.

873 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide new unambiguous definitions of site classes and rigorous empirical estimates of site-dependent amplification factors in terms of mean shear-wave velocity and input ground-motion level.
Abstract: Recent borehole‐geotechnical data and strong‐motion measurements constitute a new empirical basis to account for local geological conditions in earthquake‐resistant design and site‐dependent, building‐code provisions. They provide new unambiguous definitions of site classes and rigorous empirical estimates of site‐dependent amplification factors in terms of mean shear‐wave velocity. A simple four‐step methodology for estimating site‐dependent response spectra is specified herein. Alternative techniques and commentary are presented for each step to facilitate application of the methodology for different purposes. Justification for the methodology is provided in terms of definitions for the new site classes and derivations of simple empirical equations for amplification as a function of mean shear‐wave velocity and input ground‐motion level. These new results provide a rigorous framework for improving estimates of site‐dependent response spectra for design, site‐dependent building‐code provisions, ...

872 citations

Journal ArticleDOI
01 Mar 1991-Nature
TL;DR: In this article, the failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission, and the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process.
Abstract: The failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission. As a result, the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process which normally would occur violently in a fraction of a second. Using a procedure originally developed to locate earthquakes, acoustic emission arrival-time data are inverted to obtain three-dimensional locations of microseisms. These locations provide a detailed view of fracture nucleation and growth.

870 citations


Authors

Showing all 18026 results

NameH-indexPapersCitations
Derek R. Lovley16858295315
Steven Williams144137586712
Thomas J. Smith1401775113919
Jillian F. Banfield12756260687
Kurunthachalam Kannan12682059886
J. D. Hansen12297576198
John P. Giesy114116262790
David Pollard10843839550
Alan Cooper10874645772
Gordon E. Brown10045432152
Gerald Schubert9861434505
Peng Li95154845198
Vipin Kumar9561459034
Susan E. Trumbore9533734844
Alfred S. McEwen9262428730
Network Information
Related Institutions (5)
Lamont–Doherty Earth Observatory
8K papers, 504.5K citations

93% related

University of Alaska Fairbanks
17K papers, 750.5K citations

91% related

Scripps Institution of Oceanography
7.8K papers, 487.4K citations

90% related

Woods Hole Oceanographic Institution
18.3K papers, 1.2M citations

89% related

Swiss Federal Institute of Aquatic Science and Technology
7.2K papers, 449.5K citations

89% related

Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202367
2022224
20212,132
20202,082
20191,914
20181,920