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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
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Journal ArticleDOI
TL;DR: No clear pattern of how strongly PAHs were bound to differentBiochars was found based on the biochars' physicochemical properties, and total concentrations were below existing environmental quality standards for concentrations of PAhs in soils.
Abstract: Biochar soil amendment is advocated to mitigate climate change and improve soil fertility. A concern though, is that during biochar preparation PAHs and dioxins are likely formed. These contaminants can possibly be present in the biochar matrix and even bioavailable to exposed organisms. Here we quantify total and bioavailable PAHs and dioxins in a suite of over 50 biochars produced via slow pyrolysis between 250 and 900 °C, using various methods and biomass from tropical, boreal, and temperate areas. These slow pyrolysis biochars, which can be produced locally on farms with minimum resources, are also compared to biochar produced using the industrial methods of fast pyrolysis and gasification. Total concentrations were measured with a Soxhlet extraction and bioavailable concentrations were measured with polyoxymethylene passive samplers. Total PAH concentrations ranged from 0.07 μg g–1 to 3.27 μg g–1 for the slow pyrolysis biochars and were dependent on biomass source, pyrolysis temperature, and time. Wi...

500 citations

Journal ArticleDOI
TL;DR: In this article, the authors invert Global Positioning System and InSAR data to infer fault geometry and slip distribution associated with the Wenchuan earthquake and show that the geometry of the fault changes along its length.
Abstract: The disastrous 12 May 2008 Wenchuan earthquake in China took the local population as well as scientists by surprise Although the Longmen Shan fault zone—which includes the fault segments along which this earthquake nucleated—was well known, geologic and geodetic data indicate relatively low (<3 mm yr−1) deformation rates Here we invert Global Positioning System and Interferometric Synthetic Aperture Radar data to infer fault geometry and slip distribution associated with the earthquake Our analysis shows that the geometry of the fault changes along its length: in the southwest, the fault plane dips moderately to the northwest but becomes nearly vertical in the northeast Associated with this is a change in the motion along the fault from predominantly thrusting to strike-slip Peak slip along the fault occurs at the intersections of fault segments located near the towns of Yingxiu, Beichuan and Nanba, where fatalities and damage were concentrated We suggest that these locations represent barriers that failed in a single event, enabling the rupture to cascade through several fault segments and cause a major moment magnitude (Mw) 79 earthquake Using coseismic slip distribution and geodetic and geological slip rates, we estimate that the failure of barriers and rupture along multiple segments takes place approximately once in 4,000 years The devastating Wenchuan earthquake in 2008 struck along a fault zone that showed low rates of deformation Analysis of GPS and InSAR data suggests that, as structural barriers failed during a single earthquake, the rupture cascaded across multiple fault segments, which may explain the high magnitude of the event

500 citations

OtherDOI
01 Jan 1987
TL;DR: The most common types of mass movements that form landslide dams are rock and debris avalanches, rock and soil slumps and slides; and mud, debris, and earth flows as discussed by the authors.
Abstract: Of the numerous kinds of dams that form by natural processes, dams formed from landslides, glacial ice, and late-neoglacial moraines present the greatest threat to people and property. Landslide dams form in a wide range of physiographic settings. The most common types of mass movements that form landslide dams are rock and debris avalanches; rock and soil slumps and slides; and mud, debris, and earth flows. The most common initiation mechanisms for dam-forming landslides are excessive rainfall and snowmelt and earthquakes. Landslide dams can be classified into six categories based on their relation with the valley floor. Type I dams (11% of 184 landslide dams from around the world that we were able to classify) do not reach from one valley side to the other. Type II dams (44%) span the entire valley floor, in some cases depositing material high on opposite valley sides. Type III dams (41%) move considerable distances both upstream and downstream from the landslide failure. Type IV dams (<1%) are rare and involve the contemporaneous failure of material from both sides of a valley. Type V dams (<1%) also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river. Type VI dams (3%) involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side. Many landslide dams fail shortly after formation. In our sample of 73 documented landslide-dam failures, 27% of the landslide dams failed less than 1 day after formation, and about 50% failed within 10 days. Over-topping is by far the most common cause of failure. The timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry; material characteristics of the blockage; rate of inflow to the impoundment; size and depth of the impoundment; bedrock control of flow; and engineering controls such as artificial spill-ways, diversions, tunnels, and planned breaching by blasting or conventional excavation. Glacial-ice dams can produce at least nine kinds of ice-dammed lakes. The most dangerous are lakes formed in main valleys dammed by tributary glaciers. Failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam. Cold polar-ice dams generally drain supraglacially or marginally by downmelting of an outlet channel. Warmer, temperate-ice dams tend to fail by sudden englacial or subglacial breaching and drainage. Late-neoglacial moraine-dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries. These late-neoglacial dams pose hazards because (1) they are sufficiently young that vegetation has not stabilized their slopes, (2) many dam faces are steeper than the angle of repose, (3) these dams and lakes are immediately downslope from steep crevassed glaciers and near-vertical rock slopes, and (4) downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks. The most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls, rockfalls, or snow or rock avalanches. Melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms. Natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam. Although data are few, for the same potential energy at the dam site, ownstream flood peaks from the failure of glacier-ice dams are smaller than those from landslide, moraine, and structed earth-fill and rock-fill dam failures. Moraine-dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011-1012 joules. Differences in flood peaks natural-dam failures appear to be controlled by dam characteristics and failure mechanisms.

499 citations

Journal ArticleDOI
TL;DR: In this article, the authors used electrum-tarnish to determine the fugacity of sulfur relative to the ideal diatomic gas at 1 atm, the mol fraction of FeS in pyrrhotite (in the system FeS-S2), and the absolute temperature.

498 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
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202367
2022224
20212,132
20202,082
20191,914
20181,920