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Quantification of global forest change has been lacking despite the recognized importance of forest ecosystem services. In this study, Earth observation satellite data were used to map global forest loss (2.3 million square kilometers) and gain (0.8 million square kilometers) from 2000 to 2012 at a spatial resolution of 30 meters. The tropics were the only climate domain to exhibit a trend, with forest loss increasing by 2101 square kilometers per year. Brazil’s well-documented reduction in deforestation was offset by increasing forest loss in Indonesia, Malaysia, Paraguay, Bolivia, Zambia, Angola, and elsewhere. Intensive forestry practiced within subtropical forests resulted in the highest rates of forest change...
Categories: Publication; Types: Citation; Tags: Science
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Over the past 15 years, scientists and disaster responders have increasingly used satellite-based Earth observations for global rapid assessment of disaster situations. We review global trends in satellite rapid response and emergency mapping from 2000 to 2014, analyzing more than 1000 incidents in which satellite monitoring was used for assessing major disaster situations. We provide a synthesis of spatial patterns and temporal trends in global satellite emergency mapping efforts and show that satellite-based emergency mapping is most intensively deployed in Asia and Europe and follows well the geographic, physical, and temporal distributions of global natural disasters. We present an outlook on the future use...
Categories: Publication; Types: Citation; Tags: Science
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Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and...
Categories: Publication; Types: Citation; Tags: Science
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At least three great earthquakes occurred in the New Madrid seismic zone in 1811 and 1812. Estimates of present-day strain rates suggest that such events may have a repeat time of 1000 years or less. Paleoseismological data also indicate that earthquakes large enough to cause soil liquefaction have occurred several times in the past 5000 years. However, pervasive crustal deformation expected from such a high frequency of large earthquakes is not observed. This suggests that the seismic zone is a young feature, possibly as young as several tens of thousands of years old and no more than a few million years old.At least three great earthquakes occurred in the New Madrid seismic zone in 1811 and 1812. Estimates of...
Categories: Publication; Types: Citation; Tags: Science
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Rhenium and osmium concentrations and Os isotopic compositions of eight carbonaceous chondrites, one LL3 ordinary chondrite, and two iron meteorites were determined by resonance ionization mass spectrometry. Iron meteorite 187Re/186Os and 187OS/186Os ratios plot on the previously determined iron meteorite isochron, but most chondrite data plot 1 to 2 percent above this meteorite isochron. This suggests either that irons have significantly younger Re-Os closure ages than chondrites or that chondrites were formed from precursor materials with different chemical histories from the precursors of irons. Some samples of Semarkona (LL3) and Murray (C2M) meteorites plot 4 to 6 percent above the iron meteorite isochron,...
Categories: Publication; Types: Citation; Tags: Science
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A sample of lunar dust was examined for organic compounds. Carbon detected in concentrations of 157 micrograms per gram had a δ13C per mil (PDB) value of + 20. Treatment with hydrochloric acid yielded hydrocarbons of low molecular weight, suggesting the presence of carbides. The gas chromatogram of the acylated and esterified derivatives of the hydrolyzate was similar to that obtained for the Pueblito de Allende meteorite. There were no detectable amounts of extractable high-molecular-weight alkanes, aromatic hydrocarbons, isoprenoid hydrocarbons, normal alkanes, fatty acids, amino acids, sugars, or nucleic acid bases. Traces of porphyrins were found, perhaps arising from rocket exhaust materials.
Categories: Publication; Types: Citation; Tags: Science
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At least four active geyser-like eruptions were discovered in Voyager 2 images of Triton, Neptune's large satellite. The two best documented eruptions occur as columns of dark material rising to an altitude of about 8 kilometers where dark clouds of material are left suspended to drift downwind over 100 kilometers. The radii of the rising columns appear to be in the range of several tens of meters to a kilometer. One model for the mechanism to drive the plumes involves heating of nitrogen ice in a sub-surface greenhouse environment; nitrogen gas pressurized by the solar heating explosively vents to the surface carrying clouds of ice and dark particles into the atmosphere. A temperature increase of less than 4 kelvins...
Categories: Publication; Types: Citation; Tags: Science
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Pressure-volume-temperature relations for water at the depth of the magma chamber at 21°N on the East Pacific Rise suggest that the maximum subsurface temperature of the geothermal fluid is about 420°C. Both the chemistry of the discharging fluid and thermal balance considerations indicate that the effective water/rock ratios in the geothermal system are between 7 and 16. Such low ratios preclude effective metal transport at temperatures below 350°C, but metal solubilization at 400°C and above is effective even at such low ratios. It is proposed that the 420°C fluid ascends essentially adiabatically and in the process expands, cools, and precipitates metal sulfides within the upper few hundred meters of the sea...
Categories: Publication; Types: Citation; Tags: Science
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The Muddy Creek watershed, part of the Upper Colorado River watershed, is a semi-arid catchment in a sagebrush steppe ecosystem. A synoptic watershed assessment was conducted in 2010 to identify areas within the watershed that are more susceptible to mobilization of trace elements that occur in soils forming on marine shale. Samples of soil, stream sediment, and water were collected and assayed for major elements and a suite of trace elements. Formation waters discharged from two wells within the watershed were sampled in 2011 to evaluate their potential contribution of organic carbon, nitrogen (N) species, and trace elements to surface waters. In FY2012, analyses of the soil, rock, and water samples collected...
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Limits on the time and financial resources available for monitoring efforts, coupled with the complexities of natural resources and stakeholders, are challenges in resource monitoring. To help address these and related challenges, the USGS Monitoring Team (MT) has linked conceptual monitoring specialists with habitat and wildlife biologists to inform and develop creative, scientifically defensible approaches for monitoring the status and trends of populations and habitats across the WLCI region. This collaboration has led to spatially balanced monitoring designs that will make it possible to interpret conditions across the WLCI region and a mechanism for integrating species’ distributions and population responses...
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Regional-scale studies, such as those being conducted for the WLCI, are well suited for the use of remote-sensing techniques. Derivative products from remote-sensing instruments, such as Landsat, have been used successfully for decades in studies of geology, vegetation, environmental change, and many other types of scientific research. The continuous coverage of Landsat data since 1972 makes it possible to establish baseline conditions in areas affected by renewable and nonrenewable energy development. In this study, various Landsat datasets are being used to map current and pre-development conditions in the WLCI study area for a selected set of scientific interests. Landsat scenes have been mosaicked to produce...
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The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes’ induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite...
Categories: Publication; Types: Citation; Tags: Science
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Pollen analysis of pond deposits in the upper reaches of a stream from northeastern Iowa, an area beyond the last glacial margin, provides a nearly complete record of vegetational changes during the last 12.5 thousand years. Sixty-one radiocarbon dates provide good chronological control. Spruce forest was replaced by deciduous forest before 9 1 thousand years ago, followed by prairie from 5.4 to 3.5 thousand years ago, and oak savanna from 3.5 thousand years ago until presettlement times. The prairie invasion was nearly 3 thousand years later here than at other sites in Iowa and Minnesota, documenting a late Holocene, rather than an early-middle Holocene, period of maximum warmth and dryness for the southern part...
Categories: Publication; Types: Citation; Tags: Science
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Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity...
Categories: Publication; Types: Citation; Tags: Science
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In the WLCI region, the quality and condition of sagebrush steppe is a concern given the extent of rangewide land-use change, habitat conversion, and rapid energy development in sagebrush systems. Three migratory songbird species are considered near-obligates of sagebrush shrublands: Brewer’s and sagebrush sparrows and sage thrasher, all of which are designated Species of Great Conservation Need in Wyoming (Wyoming Game and Fish Department, 2010) and nest in Green River Basin. In collaboration with the WGFD, we initiated this multiphase project to address the WLCI management need to identify the condition and distribution of sagebrush songbird habitats and key drivers of change in those habitats. In Phase I (2008...
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Muddy Creek, a tributary to the Little Snake River, is a semi-arid catchment that drains about 1,200 mi2 in south-central Wyoming. The drainage basin is characterized as a sagebrush steppe ecosystem. The area is undergoing energy exploration and development, including conventional natural gas wells and coalbed natural gas wells. Geologic formations that underlie the drainage basin include soluble marine shales, which are a natural source of dissolved solids (for example, sodium, chloride, and sulfate) and Se. As a result, the water quality of Muddy Creek is naturally high in dissolved constituents, including Se. The WDEQ has listed chloride and Se as impairments to aquatic life for Muddy Creek. Dissolved solids...
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Theory predicts that higher biodiversity in the tropics is maintained by specialized interactions among plants and their natural enemies that result in conspecific negative density dependence (CNDD). By using more than 3000 species and nearly 2.4 million trees across 24 forest plots worldwide, we show that global patterns in tree species diversity reflect not only stronger CNDD at tropical versus temperate latitudes but also a latitudinal shift in the relationship between CNDD and species abundance. CNDD was stronger for rare species at tropical versus temperate latitudes, potentially causing the persistence of greater numbers of rare species in the tropics. Our study reveals fundamental differences in the nature...
Categories: Publication; Types: Citation; Tags: Science
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Labeled DDD [ 1,1-dichlor-o-2,2-bis(p-chlorophenyl)-ethane] was formed from C14-labeled DDT in the presence of yeast. The formation of DDD from DDE [1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene] was not observed, indicating that a reductive dechlorination of DDT occurs.
Categories: Publication; Types: Citation; Tags: Science
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Brains of juvenile gray bats, Myotis grisescens, found dead beneath maternity roosts in two Missouri caves contained lethal concentrations of dieldrin. One colony appeared to be abnormally small, and more dead bats were found a year after the juvenile bats had been collected. This is the first report to link the field mortality of bats directly to insecticide residues acquired through the food chain.
Categories: Publication; Types: Citation; Tags: Science
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[No abstract available]
Categories: Publication; Types: Citation; Tags: Science


map background search result map search result map High-resolution global maps of 21st-century forest cover change High-resolution global maps of 21st-century forest cover change