Spatial and temporal predictions of soil moisture dynamics,runoff, variable source areas and evapotranspiration for plynlimon,mid-wales     

P. F. Quinn  K. J. Beven 《水文研究》1993,7(4):425-448

For many years hydrologists have tried to build physically realistic models which are still simple enough to be fitted to a range of observations made in the field. This is an ongoing process which will become even more difficult as the quality and variety of field and remotely sensed data improves. Hence models must be able to predict soil moisture patterns in time and in space as well as the outflow hydrograph. The model presented here (TOPMODEL) aims to predict the nature of variable source areas in a way that reflects their dynamics over space and time. All component processes are described and shown in operation. As TOPMODEL and similar models have a growing popularity, this paper can be seen as a demonstration of the model's predictive capabilities. The model is applied to the catchments of Plynlimon, mid-Wales for 1984, 1985 and 1986 data sets. The model has been thoroughly tested and cross-validated against independent data sets for different time periods, for a separate catchment, for internal gauges and for wet and dry periods. The resulting predicted soil moisture patterns show a small, semi-permanent variable source area that has the ability during large storms to expand dynamically over short time periods. Spatial predictions of evapotranspiration are also shown which reflect the influence of soil moisture patterns on this process. The weakest component of the model is the representation of root zone evaporation and how this pre-sets the antecedent condition of the catchment during long dry periods.  相似文献   

Simulations of gaseous disc-embedded planet interaction     

Graeme Lufkin †  Thomas Quinn  James Wadsley  Joachim Stadel  Fabio Governato 《Monthly notices of the Royal Astronomical Society》2004,347(2):421-429

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Rates and patterns of thermal mixing at a small stream confluence under variable incoming flow conditions          下载免费PDF全文

Quinn W. Lewis  Bruce L. Rhoads 《水文研究》2015,29(20):4442-4456

Confluences are important locations for river mixing within drainage networks, yet few studies have examined in detail the dynamics of mixing within confluences. This study examines the influence of momentum flux ratio, the scale of the flow (cross‐sectional area) and the density differences between incoming flows on thermal mixing at a small stream confluence. Results reveal that rates and patterns of thermal mixing depend on event‐specific combinations of the three factors. The mixing interface at this confluence is generally distorted towards the mouth of the lateral tributary by strong helical motion associated with curvature of flow from the lateral tributary as it aligns with the downstream channel. As the momentum flux from the lateral tributary increases, mixing is enhanced because helical motion from the curving tributary flow expands over the width of the downstream channel. The cross‐sectional area of the flow is negatively correlated with mixing rates, suggesting that the amount of mixing over a fixed distance downstream of the confluence is inversely related to the scale of the flow. Density differences are not strongly related to rates of mixing. Results confirm that mixing rates within the region of confluent flow interaction can be highly variable among flow events with different incoming flow conditions, but that, in general, length scales of mixing are short, and rates of mixing are high at this small confluence compared with those typically documented at large‐river confluences. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Effects of the pharmaceuticals gemfibrozil and diclofenac on the marine mussel (Mytilus spp.) and their comparison with standardized toxicity tests     

Schmidt W  O'Rourke K  Hernan R  Quinn B 《Marine pollution bulletin》2011,62(7):1389-1395

Human pharmaceuticals, like the lipid lowering agent gemfibrozil and the non-steroidal anti-inflammatory drug diclofenac are causing environmental concern. In this study, the marine mussel (Mytilus spp.) was exposed by injection to environmentally relevant and elevated (1 μg/L and 1000 μg/L) concentrations of both compounds and biomarker expression was observed. Gemfibrozil exposure induced biomarkers of stress (glutathione S-transferase and metallothionein) at both concentrations 24 h and 96 h after exposure, respectively. Biomarkers of damage (lipid peroxidation (LPO) and DNA damage) were significantly affected, as well as the biomarker for reproduction, alkali-labile phosphate assay, indicating the potential oxidative stress and endocrine disrupting effect of gemfibrozil. Diclofenac significantly induced LPO after 96 h indicating tissue damage. Additionally standard toxicity tests using the marine species Vibrio fischeri, Skeletonema costatum and Tisbe battagliai showed differences in sensitivity to both drugs in the mg/L range. Results indicate a suite of tests should be used to give accurate information for regulation.  相似文献   

Detection and characterization of oxidizing acids in the Atacama Desert using the Mars Oxidation Instrument     

R.C. Quinn  A.P. Zent  P. Ehrenfreund  J.R.C. Garry 《Planetary and Space Science》2005,53(13):1376-1388

We have performed field experiments to further develop and validate the Mars Oxidation Instrument (MOI) as well as measurement strategies for the in situ characterization of oxidation mechanisms, kinetics, and carbon cycling on Mars. Using the Atacama Desert as a test site for the current dry conditions on Mars, we characterized the chemical reactivity of surface and near-surface atmosphere in the dry core of the Atacama. MOI is a chemiresistor-based sensor array that measures the reaction rates of chemical films that are sensitive to particular types of oxidants or that mimic chemical characteristics of pre-biotic and biotic materials. With these sensors, the chemical reactivity of a planetary environment is characterized by monitoring the resistance of the film as a function of time. Our instrumental approach correlates reaction rates with dust abundance, UV flux, humidity, and temperature, allowing discrimination between competing hypotheses of oxidant formation and organic decomposition. The sensor responses in the Atacama are consistent with an oxidative attack by strong acids triggered by dust accumulation, followed by transient wetting due to an increase in relative humidity during the night. We conclude that in the Atacama Desert, and perhaps on Mars, low pH resulting from acid accumulation, combined with limited water availability and high oxidation potential, can result in oxidizing acid reactions on dust and soil surfaces during low-moisture transient wetting events (i.e. thin films of water). These soil acids are expected to play a significant role in the oxidizing nature of the soils, the formation of mineral surface coatings, and the chemical modification of organics in the surface material.  相似文献   

Dissolved copper and copper-organic complexes in the Narragansett Bay estuary     

Gary L. Mills  James G. Quinn 《Marine Chemistry》1984,15(2):151-172

The geochemistry of dissolved copper-organic complexes was investigated in the estuarine waters of Narragansett Bay. A transect survey was conducted in August 1980, while one mid-bay station was monitored from March through August of that year. The transect data indicated that most of the copper-organic complexes enter the bay via sewage effluent which is discharged into the Providence River at the head of the bay. Organic copper concentrations in the estuary ranged from 0.12 to 2.30 μg kg^?1 and comprised from 14 to 70% of the total dissolved copper. The concentration of copper-organic complexes was not directly related to the amount of dissolved organic matter; and recently generated organic material from phytoplankton production within the bay had a negligible influence on the fraction of dissolved copper which was organically bound.The major source of total copper to the bay is anthropogenic inputs from sewage effluents. Particulate and dissolved copper concentrations ranged from 0.06 to 2.42 and 0.23 to 16.4 μg kg^?1, respectively, giving average values of about 40% particulate and 60% dissolved copper. Particulate copper concentrations decreased rapidly from the upper to the lower bay as a result of both removal and dilution. About 75% of the dissolved copper entering the bay is rapidly removed in the Providence River and upper bay, and the remaining portion (which is largely organic copper) follows conservative mixing in the mid to lower bay. The data suggest that copper binding by dissolved organic matter may be an important control on the riverine flux of dissolved copper through estuaries into coastal and oceanic waters.  相似文献   

The effect of non-gravitational gas heating in groups and clusters of galaxies     

S. Borgani  F. Governato  J. Wadsley  N. Menci  P. Tozzi  T. Quinn  J. Stadel  G. Lake 《Monthly notices of the Royal Astronomical Society》2002,336(2):409-424

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The origin and properties of intracluster stars in a rich cluster     

Beth Willman  Fabio Governato †  James Wadsley  Thomas Quinn 《Monthly notices of the Royal Astronomical Society》2004,355(1):159-168

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The inner structure of ΛCDM haloes – II. Halo mass profiles and low surface brightness galaxy rotation curves     

E. Hayashi  J. F. Navarro  C. Power  A. Jenkins  C. S. Frenk  S. D. M. White  V. Springel  J. Stadel  T. R. Quinn 《Monthly notices of the Royal Astronomical Society》2004,355(3):794-812

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Far-Infrared/Submillimeter Astronomical Interferometry with Spaceborne Tether Formations     

Enrico Lorenzini  Claudio Bombardelli  Mario Cosmo  Martin Harwit  David Leisawitz  Rodger Farley  Stephen Rinehart  David Quinn  David Miller 《Astrophysics and Space Science》2006,302(1-4):225-239

Through the continuing development of improved detectors and detector arrays, far-infrared/submillimeter astronomical space missions have had enormous successes in recent years. Despite these advances, the diffraction-limited angular resolving power has remained virtually constant. The advent of telescopes with apertures of several meters will improve this capability, but will still leave image resolution many orders of magnitude poorer than in most other spectral ranges. Here we point out that the only foreseeable way to improve image quality to rival that of modern optical telescopes will be with interferometers whose light collectors are connected by tethers. After making the scientific case for high spatial resolution far-infrared/submillimeter imaging and the use of interferometry as the most immediate way of producing results, we discuss recent advances in dynamic analysis and control of tethered formations, and argue that the further development and testing of tethers in space is a first step toward providing improved far-infrared/submillimeter angular resolution and astronomical image quality.  相似文献