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Submarine alkalic and transitional basalts collected by submersible along Kilauea volcano's south flank represent early eruptive products from Earth's most active volcano. Strongly alkalic basalt fragments sampled from volcaniclastic deposits below the mid-slope Hilina Bench yield 40Ar/39Ar ages from 212±38 to 280±20 ka. These ages are similar to high-precision 234±9 and 239±10 ka phlogopite ages from nephelinite clasts in the same deposits. Above the mid-slope bench, two intact alkalic to transitional pillow lava sequences protrude through the younger sediment apron. Samples collected from a weakly alkalic basalt section yield 138±30 to 166±26 ka ages and others from a transitional basalt section yield 138±115...
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From September 1999 through April 2004, Shishaldin Volcano, Aleutian Islands, Alaska, exhibited a continuous and extremely high level of background seismicity. This activity consisted of many hundreds to thousands of long-period (LP; 1–2 Hz) earthquakes per day, recorded by a 6-station monitoring network around Shishaldin. The LP events originate beneath the summit at shallow depths (0–3 km). Volcano tectonic events and tremor have rarely been observed in the summit region. Such a high rate of LP events with no eruption suggests that a steady state process has been occurring ever since Shishaldin last erupted in April–May 1999. Following the eruption, the only other signs of volcanic unrest have been occasional...
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Large N2O emissions were observed from intertidal sediments in a coastal estuary, West Falmouth Harbor, MA, USA. Average N2O emission rates from 41 chambers during summer 2008 were 10.7 mol N2O m(-2) h(-1)±4.43 μmol N2O m(-2) h(-1) (standard error). Emissions were highest from sediments within a known wastewater plume, where a maximum N2O emission rate was 155 μmol N2O m(-2) h(-1). Intertidal N2O fluxes were positively related to porewater ammonium concentrations at 10 and 25 cm depths. In groundwater from 7 shoreline wells, dissolved N2O ranged from 488% of saturation (56 nM N2O) to more than 13000% of saturation (1529 nM N2O) and was positively related to nitrate concentrations. Fresh and brackish porewater underlying...
Categories: Publication; Types: Citation; Tags: Chemosphere
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To better understand the effects of partial cutting on arboreal lichen production within woodland caribou (Rangifer tarandus caribou) habitat, lichen was hand picked from 1228 branches on 307 subalpine fir (Abies lasiocarpa) trees in Idaho (ID), and in British Columbia (BC). Lichen biomass from partially cut stands was compared with biomass on trees from adjacent uncut stands at each site. Arboreal lichen biomass did not differ significantly between uncut and partially cut stands. Total number of branches per tree did not differ significantly between uncut and partially cut stands. Live branches had more lichen than dead branches. Species composition of arboreal lichen changed in partially cut stands compared with...
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The 2009 eruption of Redoubt Volcano included 20 tephra-producing explosions between March 15, 2009 and April 4, 2009 (UTC). Next-Generation radar (NEXRAD) data show that plumes reached heights between 4.6 km and 19 km asl and were distributed downwind along nearly all azimuths of the volcano. Explosions lasted between < 1 and 31 min based on the signal duration at a distal seismic station (86 km). From Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and field data, we estimate that over 80,000 km2 received at least minor ash fall (> 0.8 mm thick), including communities along the Kenai Peninsula (80–100 km) and the city of Anchorage (170 km). Trace ash (< 0.8 mm) was reported as far as Fairbanks, 550...
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Degradates of acetochlor and alachlor (ethanesulfonic acids, ESAs) were analyzed in both standards and in a groundwater sample using high-performance liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. The negative pseudomolecular ion of the secondary amide of acetochlor ESA and alachlor ESA gave average masses of 256.0750+/-0.0049 amu and 270.0786+/-0.0064 amu respectively. Acetochlor and alachlor ESA gave similar masses of 314.1098+/-0.0061 amu and 314.1153+/-0.0048 amu; however, they could not be distinguished by accurate mass because they have the same empirical formula. On the other hand, they may be distinguished using positive-ion electrospray because of different fragmentation...
Categories: Publication; Types: Citation; Tags: Journal of Chromatography A
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The volcanic islands making up the Azores Archipelago rise above sea from a prominent submarine topographic high (the “Azores Plateau”), marked by the 2000-m bathymetric contour. Specifically, the Azores Islands lie at the so-called “Azores Triple Junction” (ATJ), where the Eurasian, North American, and African (or Nubian) tectonic plates meet. In general terms, the ATJ is defined by the Mid-Atlantic Ridge (MAR) separating the North American plate from the other two, and the Azores–Gibraltar fault zone separating the Eurasian and African plates. In addition, the existence of a mantle plume (“hotspot) beneath Azores Plateau has been inferred in many previous investigations. Not surprisingly, because of its distinctive...
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The 18 papers herein report on new geodetic data that offer valuable insights into eruptive activity and magma transport; they present new models and modeling strategies that have the potential to greatly increase understanding of magmatic, hydrothermal, and volcano-tectonic processes; and they describe innovative techniques for collecting geodetic measurements from remote, poorly accessible, or hazardous volcanoes. To provide a proper context for these studies, we offer a short review of the evolution of volcano geodesy, as well as a case study that highlights recent advances in the field by comparing the geodetic response to recent eruptive episodes at Mount St. Helens. Finally, we point out a few areas that continue...
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The presence of endocrine-disrupting compounds (EDCs), particularly estrogenic compounds, in the environment has drawn public attention across the globe, yet a clear understanding of the extent and distribution of estrogenic EDCs in surface waters and their relationship to potential sources is lacking. The objective of the present study was to identify and examine the potential input of estrogenic EDC sources in North Carolina water bodies using a geographic information system (GIS) mapping and analysis approach. Existing data from state and federal agencies were used to create point and nonpoint source maps depicting the cumulative contribution of potential sources of estrogenic EDCs to North Carolina surface waters....
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Crayfish (Orconectes spp.), Asian clam (Corbicula fluminea), northern hog sucker (hog sucker; Hypentelium nigricans), and smallmouth bass (smallmouth; Micropterus dolomieu) from streams in southeastern Missouri (USA) were analyzed for total mercury (HgT) and for stable isotopes of carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) to discern Hg transfer pathways. HgT concentrations were generally lowest in crayfish (0.005-0.112 μg/g dw) and highest in smallmouth (0.093-4.041 μg/g dw), as was δ¹⁵N. HgT was also lower and δ¹⁵N was higher in all biota from a stream draining a more heavily populated historical lead-zinc mining area than from similar sites with mostly undeveloped forested watersheds. δ¹³C in biota was...