Smithsonian Institution's Global Volcanism Network     

Rick Wunderman 《Bulletin of Volcanology》2002,64(8):564-565

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A Geostatistically Based Ground Water Monitoring Study of Nonpoint Source No₃^--N Concentrations     

Rick A. Carlson  James L. Osiensky 《Ground Water Monitoring & Remediation》2002,22(4):109-115

Geostatistical interpretations of ground water monitoring data are presented to define the spatial distributions of NO₃^--N in the ground water at two demonstration test sites in the Idaho Snake River Plain. Sequential Gaussian simulation was used to delineate monthly ground water NO₃^--N changes during and after implementation of a prescribed crop rotation at test site 1. Trend surface analyses were used to illustrate monthly ground water NO₃^--N changes during and after a prescribed irrigation practice was implemented at test site 2. These evaluations suggest that geostatistically based ground water monitoring can be effective in the delineation of changes in ground water quality in shallow, unconfined aquifers in agricultural areas such as those in southern Idaho. Geostatistical methods showed spatial and temporal changes in ground water NO₃^--N inferred to be a result of the agricultural practices implemented.  相似文献   

Ground-Water Contaminant Plume Differentiation and Source Determination Using BTEX Concentration Ratios     

Y. Jeffrey Yang  Rick D. Spencer  Mark A. Mersmann  Todd M. Gates 《Ground water》1995,33(6):927-935

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The groundwater management plan: in praise of a neglected ‘tool of our trade’     

Stephen Foster  Rick Evans  Oscar Escolero 《Hydrogeology Journal》2015,23(5):847-850

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Developing interactive geospatial holograms for spatial decision-making     

Sven Fuhrmann  Mark E. Holzbach  Rick Black 《制图学和地理信息科学》2015,42(4):27-33

Spatial decision-making in time-critical situations requires effective and usable two-dimensional and three-dimensional (3D) cartographic products. Holographic displays allow decision makers to work with auto-stereoscopic maps without the hassle of interacting with complex user interfaces or additional vision hardware. Holographic production processes have advanced greatly in a short period and now support timely and full integration of digital 3D models in geospatial holograms. George Mason University’s and Zebra Imaging’s research on interactive holographic motion displays showcases the leadership in moving cartography and geovisualization research in the US forward. In close cooperation with academic researchers, decision makers, and domain experts, the usability and usefulness of these cartographic products is tested and design guidelines for effective geospatial holograms are being developed.  相似文献   

Fluvial processes and environmental change A.G. BROWN and T.A. QUINE (eds) Publisher John Wiley & Sons,Chichester 1999 (413 pp) $160 ISBN 0‐471‐98548‐1     

Rick Shakesby 《第四纪科学杂志》2000,15(5):562-563

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The White Angel: A unique wollastonite‐bearing,mass‐fractionated refractory inclusion from the Leoville CV3 carbonaceous chondrite     

Catherine L. V. Caillet Komorowski  Ernst K. Zinner  Kevin D. McKeegan  Rick Hervig  Peter R. Buseck 《Meteoritics & planetary science》2007,42(7-8):1159-1182

Abstract— We report the study of an unusual compact type A refractory inclusion, named the White Angel, from the Leoville CV3 meteorite. The petrologic, mineral chemical, isotopic, and trace‐element signatures of this once‐molten Ca‐Al‐rich inclusion (CAI), which contains large, equant wollastonite crystals, indicate a short multistage history that occurred very early, before substantial decay of ²⁶Al. Magnesium in the inclusion is isotopically heavy, with F_Mg reaching 18‰/amu, in the range of fractionated and with unidentified nuclear effects (FUN) inclusions. However, the absence of any nuclear anomalies in Ca and Ti and an inferred ²⁶Al/²⁷Al ratio of (5.5 ± 0.9) × 10^?5 indicate that the White Angel belongs to the F inclusions. Silicon and oxygen are also mass fractionated in favor of the heavy isotopes, but to a lesser extent. The O isotopes show a range in ¹⁶O excesses. On an O three‐isotope plot, data points lie on a line parallel and to the right of the carbonaceous chondrite anhydrous mineral mixing line, with wollastonite being the most ¹⁶O‐rich phase. The chondrite‐normalized rare earth and trace‐element pattern of the whole inclusion is the complement of an ultrarefractory pattern indicating that precursor phases of the CAI must have condensed in an Al‐, heavy rare earth element (HREE)‐depleted reservoir. Melting of those precursor phases in an ¹⁶O‐rich environment and evaporation led to mass‐dependent isotopic fractionation of Mg, Si, and O. Partial isotopic exchange with a reservoir containing unfractionated Mg took place at a later stage but before any measurable decay of ²⁶Al. Some minerals (melilite and perovskite) in the White Angel equilibrated oxygen isotopes with a relatively ¹⁶O‐poor reservoir that was also mass‐fractionated toward the heavy isotopes, different from that with which the normal or FUN inclusions interacted.  相似文献   

Anthropogenic disturbance history influences the temporal coherence of paleoproductivity in two lakes     

Biplob Das  Anita Narwani  Blake Matthews  Rick Nordin  Asit Mazumder 《Journal of Paleolimnology》2009,42(2):167-181

We investigated how the history of local disturbances in a watershed can influence the regional coherence of ecosystem properties in lakes that have similar morphometry and climatic conditions. We measured sedimentary δ¹³C, δ¹⁵N, C:N and %BSiO₂ in Sooke Lake Reservoir (SOL) and Shawnigan Lake (SHL), which are located within 4 km of each other on Vancouver Island, Canada. SOL is an impounded lake whose watershed has been fully protected over the last century, although the lake level has been raised 3 times via impoundment during this period. SHL has a similar limnological regime, but the surrounding watershed has been developed extensively for residential uses. We investigated how a pulse disturbance regime in SOL (i.e. repeated dam raising) and a press disturbance regime in SHL (i.e. persistent development) influenced the variability of paleoindicators in each system over time. We found that these contrasting disturbance regimes reduced the regional temporal coherence of aquatic productivity between the two lakes (indicated by %BSiO₂), but did not influence the regional coherence of nutrient status or the main carbon sources of the lakes (indicated by %C, %N and δ¹³C). In contrast, an indicator of the sources and cycling of nitrogen (δ¹⁵N) showed increased coherence. Local disturbances also affected the variability of the paleoindicators within each system over time. In SOL, impoundments led to both declines (%N, δ¹⁵N) and increases (δ¹³C) in the variability of paleoindicators. In SHL, persistent watershed development led to lower variability of two paleoindicators (%N, %BSiO₂). Overall, our data suggest that local disturbances can influence the %BSiO₂ and C:N ratio of lake sediments, but are less likely to alter the regional coherence of %C, %N and δ¹³C between lakes. Biplob Das and Anita Narwani contributed equally to this work.  相似文献   

Evolution of Bioreactor Technologies for High-Concentration Contaminant Mixes in Groundwater     

John Horst  Jon Forbort  Mark Klemmer  Jen Kao  Robert J. Stuetzle  Rick Wenzel 《Ground Water Monitoring & Remediation》2019,39(3):12-22

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Local Fractional Frequency Shifts Used as Tracers of Magnetic Activity     

Hindman  Bradley  Haber  Deborah  Toomre  Juri  Bogart  Rick 《Solar physics》2000,192(1-2):363-372

Using data from SOI-MDI (Haber et al., 2000), we compute the local frequencies of high-degree p modes and f modes. The frequencies are obtained through ring-diagram mode fitting. The Dense-Pack data set consists of a mosaic of 189 overlapping tiles, each tracked separately at the surface rotation rate over 1664-min time intervals during the Dynamics Programs. Each tile is 16° square and the tile centers are separated by 7.5° in latitude and longitude. For each sampling day and for each tile, we have computed the frequency shift measured relative to the temporal and spatial average of the entire set of frequencies. The motion of active regions as they rotate across the solar disk is vividly traced by these measurements. Active regions appear as locations of large positive frequency shifts. If the shifts are averaged over the solar disk and are scaled down to the appropriate wave number regime, the magnitude and frequency dependence of the shifts are consistent with the measured changes in global oscillation frequencies that occur over the solar cycle. As with the frequency shifts of low-degree global oscillations, the frequency dependence of the shifts indicates that the physical phenomena inducing the shifts is confined to the surface layers of the Sun.  相似文献