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   

Book review     

B. Rick 《Rock Mechanics and Rock Engineering》1987,20(2):147-148

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Influence of diet on growth, condition and reproductive capacity in Newfoundland and Labrador cod (Gadus morhua): Insights from stable carbon isotopes (δC)     

Graham D. Sherwood  Rick M. Rideout  Susan B. Fudge  George A. Rose 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2794

Cod populations in Newfoundland and Labrador waters have shown differing growth, condition and recruitment since near-universal declines in these properties during the cold period of the late 1980s and early 1990s. To assess the influence of variable prey communities on these parameters, we compared cod energetics and diet in populations off Labrador and the northeast and south coasts of Newfoundland. Many properties were highest in the southern group(s) and lowest in the northern group(s), including growth, somatic condition, liver index and age-at-maturity. Most differences could be explained by variations in diet, as measured by stomach contents and stable carbon isotopes (δ¹³C). The diet of Labrador cod consisted almost entirely of northern shrimp (Pandalus borealis), and these cod displayed the most benthic δ¹³C signatures. Northeast cod had a more varied diet that included capelin and other fish, but still had mostly benthic δ¹³C signatures, suggesting the importance of benthic prey like shrimp in this population. South coast cod exhibited the most varied diet, including capelin (Mallotus villosus), zooplankton, crabs and other fish, and had the most pelagic δ¹³C signatures. Among and within populations, the benefits of a more pelagic diet in medium-sized (30–69 cm) cod included higher somatic condition, higher liver index (lipid stores) and greater spawning potential (decreased incidence of atresia). It is hypothesized that major rebuilding of Newfoundland and Labrador cod stocks will require a return to a system that supports mostly pelagic feeding (i.e. capelin) in cod.  相似文献   

Strategies for waveform processing in sparker data     

Mathieu J. Duchesne  Gilles Bellefleur  Mike Galbraith  Randy Kolesar  Rick Kuzmiski 《Marine Geophysical Researches》2007,28(2):153-164

A sparker is a marine seismic impulsive source used for high-resolution seismic surveys. Sparker sources were very popular during the late 1960s and 1970s before being supplanted by small volume airguns. However, in the last 10 years there has been renewed interest in sparker technology because (1) it can be easily deployed at relatively low costs and (2) in certain areas the use of small airguns is restricted for environmental purposes. In this study a sparker source was used to assess the seismic stratigraphy of Quaternary deposits and to image the sediment/bedrock interface. Three different inverse filtering methods were tested (i.e., spiking deconvolution, match-filtering and vertical seismic profile (VSP) deconvolution) to correct the poor shot-to-shot repeatability of the source and to compress its reverberations. Results show that the matched-filter and VSP deconvolution methods, which design and apply one operator for each shot, produced comparable results, whereas the spiking deconvolution that used the same operator on all traces failed to compress the source signature properly.  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