A GIS-Based Ground Water Contamination Risk Assessment Tool for Pesticides   总被引：4，自引：0，他引：4  

Michael G. Sinkevich Jr  .  M. Todd Walter  Arthur J. Lembo Jr  .  Brian K. Richards  Natalia Peranginangin  Sunnie A. Aburime  Tammo S. Steenhuis 《Ground Water Monitoring & Remediation》2005,25(4):82-91

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Digital Photogrammetric Monitoring of River Bank Erosion     

C. J. Pyle  K. S. Richards  J. H. Chandler 《The Photogrammetric Record》1997,15(89):753-764

Detailed understanding of the processes which control river bank erosion requires high resolution information concerning temporal changes in bank morphology. This paper describes the successful use of digital photogrammetry to extract high resolution digital elevation models (DEMs) from terrestrial oblique stereopairs of rapidly eroding river banks, using the commercial software package Erdas Imagine. This software was developed for use with aerial photography and satellite imagery; problems relating to the use of oblique terrestrial images are discussed and solutions presented. Photography was acquired using semi-metric cameras, mounted on tripods and positioned about 15m from the eroding bank. Data for DEM point spacings of 20mm were obtained, with accuracies of approximately ±12mm in depth. Digital photogrammetry can permit faster analysis, provide better accuracies and involve less ground disturbance than conventional methods of monitoring river channel change. Most importantly, DEM generation is considered to be more useful than traditionally acquired points or profiles for landform monitoring strategies.  相似文献   

Shellfish-associated enteric virus illness in the United States, 1934–1984     

Gary P. Richards 《Estuaries and Coasts》1987,10(1):84-85

The regulation of shellfish and their growing waters is based on total and fecal coliform standards. Application of these standards has reduced the incidence of shellfish-borne bacterial illnesses in humans, but outbreaks of viral diseases, such as hepatitis A, Norwalk illness, and viral gastroenteritis, prevail. Hepatitis A virus contributed to 1,395 cases of shellfish-associated illness since 1961. An additional 6,049 cases of shellfish-associated gastroenteritis were reported over the past 50 years, 75% of which (4,609 cases) occurred since 1980. The alarming rate of disease outbreaks during the past 5 years may further increase as better reporting practices are initiated by health professionals and state and federal agencies. Actions necessary to reduce the incidence of shellfish-associated viral illness include development of methods for detecting viral pathogens in shellfish and harvest waters, correlation of levels of viral pathogens with potential viral and bacterial indicators, and acceleration of field monitoring and enforcement efforts.  相似文献   

Book review     

Paul G. Richards  James A. Carton  Pierre De Mey  James A. Carton 《Pure and Applied Geophysics》1985,123(4):646-672

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Krakatau 1883—The volcanic eruption and its effects,T. Simkin and R. S. Fiske,Smithsonian Institution Press,Washington DC, 1983. No. of pages: 464, 139 black and white, 49 colour plates and figures. Price: $15.00. ISBN 0-87474-841-0     

Keith Richards 《地球表面变化过程与地形》1985,10(1):90-91

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Some observations on suspended sediment dynamics in Storbregrova,Jotunheimen     

Keith Richards 《地球表面变化过程与地形》1984,9(2):101-112

Observations are reported of the dynamics of suspended sediment transport in the meltstream of Storbreen in the Jotunheimen. Fine sediment is transferred from the subglacial to the proglacial environment during low flow (meltdominated) periods, and then removed from the catchment during high flow (rainfall-controlled) events. Both diurnal and storm period sediment load-discharge relationships involve clockwise hysteresis, but separate multivariate rating curves define variations of load with streamflow according to (1) the relative importance of meltwater and rainfall runoff, and (2) changes in the sediment source areas contributing to the stream at different times. Particle size variations in the suspended sediment also reflect varying source area influences.  相似文献   

A numerical investigation of the formation and evolution of magnetospheric irregularities by the interchange of magnetic flux tubes     

P.G. Richards  K.D. Cole 《Planetary and Space Science》1979,27(11):1351-1360

The formation and evolution of magnetospheric irregularities by interchange of tubes of force, is studied through the solution of the electron and ion heat, and ion density equations. These calculations indicate that interchange of magnetic flux tubes may cause irregularities in the ionosphere and protonosphere. Ionospheric irregularities result from disturbance of the F-layer through electrodynamic movement vertically while the protonospheric irregularities result from variations in flux tube volume. It has been found that the temperature profile plays an important role in the variation of irregularity magnitude along flux tubes and that irregularities will persist for many hours at night. After several hours a small growth of the irregularities has been observed.  相似文献   

Solid-state astrochemistry in star-forming regions     

Helen Fraser  David Williams  Ian Sims  Anita Richards  Jeremy Yates 《Astronomy& Geophysics》2003,44(4):4.29-4.33

Surface-catalysed chemical reactions, the molecules they form, and the implications for star formation were key themes in an international workshop on "Solid-state chemistry in star-forming regions" at the Lorentz Centre, Leiden University, the Netherlands from 14–17 April 2003. Helen Fraser, David Williams, Ian Sims, Anita Richards and Jeremy Yates report.  相似文献   

Contrasting magmas in metapelitic and metapsammitic migmatites in the Cooma Complex, Australia     

R. H. Vernon  W. J. Collins  S. W. Richards 《Visual Geosciences》2003,8(1):1-22

Metapelite-derived migmatites (“bedded migmatites”) formed in the low-pressure/high-temperature (LPHT) Cooma Complex, southeastern Australia, contain magma (neosome and leucosome) confined to the metapelitic beds in which they were generated. The metapsammitic beds were more ductile than the metapelitic beds (and the metapelitic parts of graded beds), which underwent fracture and boudinage, thereby providing space for the magma, though some also occurs in axial surface folia. Transitions from bedded to stromatic migmatites can be seen, but the magma mainly remained in the metapelites, even in the most strongly deformed stromatic migmatites. This, together with boudinage and transposition of the leucosome, as well as microstructural evidence of quartz recrystallization, suggest that much or most of the stromatic layering was formed by solid-state deformation. In contrast, magmas (neosomes) formed by partial melting of feldspathic metapsammites at Cooma moved out of their parent rocks, and coalesced into veins and small intrusions of diatexite, because (1) the host rocks deformed more homogeneously, and no interboudin space was made for the melts, and (2) the melt escape threshold was exceeded, probably with the assistance of deformation. Metapsammite melting occurred after solidification of the metapelite-derived magma, and the mobile metapsammite-derived magma (diatexite) disrupted and incorporated fragments of the metapelitic migmatites. The metapsammite-derived magma, together with this solid metapelitic material, locally coalesced into bodies closely resembling the Cooma Granodiorite.  相似文献   

Characteristics of deep groundwater flow in a basin marginal setting at Sellafield,Northwest England: Cl and halide evidence     

Richard Metcalfe  Mark B. Crawford  Adrian H. Bath  Anna K. Littleboy  Paul J. Degnan  Hugh G. Richards 《Applied Geochemistry》2007

A number of chemical and physical processes inside and outside a sedimentary basin (e.g. evaporite dissolution and topographic drive, respectively) affect groundwater flow near the basin’s margin. Contrasting formations at the margin, typically basinal sedimentary rocks and basement, are host to the interplay between these processes so that groundwater flows and compositions change within a relatively small volume. To interpret how groundwater flow and geochemistry have evolved, interactions between these processes must be understood. Such interactions were investigated near the margin of the East Irish Sea Basin in NW England, by sampling deep groundwaters (to 1500 m below sea level) from Ordovician volcanic basement rocks and Carboniferous to Triassic sedimentary cover rocks. Variable Br/Cl ratios and Cl concentrations in deep saline waters and brines indicate mixing patterns. Variations in ³⁶Cl/Cl constrain the timing of mixing. Relatively low Br/Cl ratios (ca. 1 × 10⁻³ by mass) characterise brine from the western sedimentary cover and reflect halite dissolution further west. Saline water with relatively high Br/Cl ratios (ca. 2 × 10⁻³ by mass) of uncertain origin occupies the eastern basement. These two waters mix across the area. However, mixing alone cannot explain variable ³⁶Cl/Cl ratios, which partly reflect differing in situ³⁶Cl production rates in different rock formations. Most ³⁶Cl/Cl ratios in groundwater sampled from the eastern metavolcanic basement (mean = 25 × 10⁻¹⁵) and western sedimentary cover (mean = 10 × 10⁻¹⁵) are at or close to equilibrium with in situ³⁶Cl production. These variations in ³⁶Cl/Cl across the site possibly took >1.5 Ma to be attained, implying that deep groundwater flow responded only slowly to the Quaternary glaciation of the site. Interplay between varied processes in basin marginal settings does not necessarily imply flow instability.  相似文献