Methane in an acidic bog lake: The influence of peat in the catchment on the biogeochemistry of methane   总被引：3，自引：0，他引：3  

Peter Casper  On Chim Chan  Andre L. S. Furtado  Donald D. Adams 《Aquatic Sciences - Research Across Boundaries》2003,65(1):36-46

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An evaluation of the role played by remote sensing technology following the World Trade Center attack     

Charles?K.?HuyckEmail author  Beverley?J.?Adams  David?I.?Kehrlein 《地震工程与工程振动(英文版)》2003,2(1):159-168

Remote sensing technology has been widely recognized for contributing to emergency response efforts after the World Trade Center attack on September 11th, 2001. The need to coordinate activities in the midst of a dense, yet relatively small area, made the combination of imagery and mapped data strategically useful. This paper reviews the role played by aerial photography, satellite imagery, and LIDAR data at Ground Zero. It examines how emergency managers utilized these datasets, and identifies significant problems that were encountered. It goes on to explore additional ways in which imagery could have been used, while presenting recommendations for more effective use in future disasters and Homeland Security applications. To plan adequately for future events, it was important to capture knowledge from individuals who responded to the World Trade Center attack. In recognition, interviews with key emergency management and geographic information system (GIS) personnel provide the basis of this paper. Successful techniques should not be forgotten, or serious problems dismissed. Although widely used after September 11th, it is important to recognize that with better planning, remote sensing and GIS could have played an even greater role. Together with a data acquisition timeline, an expanded discussion of these issues is available in the MCEER/NSF report “Emergency Response in the Wake of the World Trade Center Attack; The Remote Sensing Perspective” (Huyck and Adams, 2002)  相似文献   

Application of matrix analysis in delineating sinkhole risk areas along highway (I-70 near Frederick,Maryland)     

Wanfang?ZhouEmail author  Barry?F.?Beck  Angela?L.?Adams 《Environmental Geology》2003,44(7):834-842

Sinkhole collapse in the area of Maryland Interstate 70 (I-70) and nearby roadways south of Frederick, Maryland, has been posing a threat to the safety of the highway operation as well as other structures. The occurrence of sinkholes is associated with intensive land development. However, the geological conditions that have been developing over the past 200 million years in the Frederick Valley control the locations of the sinkholes. Within an area of approximately 8 km², 138 sinkholes are recorded and their spatial distribution is irregular, but clustered. The clustering indicates the existence of an interaction between the sinkholes. The point pattern of sinkholes is considered to be a sample of a Gibbsian point process from which the hard-core Strauss Model is developed. The radius of influence is calculated for the recorded sinkholes which are most likely to occur within 30 m of an existing sinkhole. The stochastic analysis of the existing sinkholes is biased toward the areas with intensive land use. This bias is adjusted by considering (1) topography, (2) proximity to topographic depressions, (3) interpreted rock formation, (4) soil type, (5) geophysical anomalies, (6) proximity to geologic structures, and (7) thickness of overburden. Based on the properties of each factor, a scoring system is developed and the average relative risk score for individual 30-m segments of the study area is calculated. The areas designated by higher risk levels would have greater risk of a sinkhole collapse than the areas designated by lower risk levels. This risk assessment approach can be updated as more information becomes available.  相似文献   

Development of a coupled surface-groundwater-pipe network model for the sustainable management of karstic groundwater   总被引：1，自引：0，他引：1  

R. Adams  G. Parkin 《Environmental Geology》2002,42(5):513-517

This paper considers the hydrogeological simulation of groundwater movement in karstic regions using a hydrological modelling system (SHETRAN) which has been adapted for modelling flow in karstic aquifers. Flow and transport through karstic aquifers remains poorly understood, yet quantitative hydrogeological models are essential for developing and implementing groundwater protection policies. The new model has been developed and used within the STALAGMITE (Sustainable Management of Groundwater in Karstic Environments) project, funded by the European Commission. The SHETRAN model is physically based insofar as most of the parameters have some physical meaning. The SHETRAN model represents all of the key processes in the hydrological cycle, including subsurface flow in the saturated and unsaturated zones, surface flow over the ground surface and in channels, rainfall interception by vegetation canopies, evapotranspiration, snow-pack development and snowmelt. The modifications made to SHETRAN to simulate karstic aquifers are (1) the coupling of a pipe network model to a variably saturated, three-dimensional groundwater component (the VSS-NET component), to simulate flow under pressure in saturated conduits; (2) the coupling of surface water features (e.g. sinking streams or "ponors", and spring discharges) to the conduit system; (3) the addition of a preferential "bypass" flow mechanism to represent vertical infiltration through a high-conductivity epikarst zone. Lastly, a forward particle tracking routine has been developed to trace the path of hypothetical particles with matrix and pipe flow to springs or other discharge points. This component allows the definition of groundwater protection zones around a source for areas of the catchment (watershed) which are vulnerable to pollution from non-point sources (agriculture and forestry).  相似文献   

Biomass Burning in Southern Africa: Individual Particle Characterization of Atmospheric Aerosols and Savanna Fire Samples   总被引：2，自引：0，他引：2  

Xiande Liu  Piet Van Espen  Freddy Adams  Jan Cafmeyer  Willy Maenhaut 《Journal of Atmospheric Chemistry》2000,36(2):135-155

Ambient atmospheric aerosols and savanna fireparticulate emission samples from southern Africa werecharacterised in terms of particle classes and theirnumber abundance by electron probe X-ray microanalysis(EPXMA). About ten particle classes were identifiedfor each sample. The major classes werealuminosilicates and sea salts for ambient coarse(2–10 m equivalent aerodynamic diameter (EAD))samples, and K-S and S-only particles for ambient fine(<2 m EAD) samples. The K-S particles are oneof the major products of biomass burning. The EPXMAresults were found to be consistent with the resultsfrom bulk analyses on a sample by sample basis. Forsavanna fire fine samples, quantitative EPXMA revealedthat many particles had a composition of simple saltssuch as KCl. Some particles had a deviatingcomposition in the sense that more ionic species wereinvolved in sustaining the balance between cations andanions, and they were composite or mixed salts.Because of extensive processing during the atmospherictransport, the composition of the K-S particles in theambient samples was different from K₂SO₄,and such particles were enriched with S. The finepyrogenic KCl particles and the fine sea-saltparticles were much depleted in chlorine.  相似文献   

Carbon sources of fish in an Amazonian floodplain lake     

A. Cristina B. Oliveira  M. Gercilia M. Soares  L. Antonio. Martinelli  M. Zacarias. Moreira 《Aquatic Sciences - Research Across Boundaries》2006,68(2):229-238

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Discovery of Precambrian rocks in New Zealand: Age relations of the Greenland Group and Constant Gneiss,West Coast,South Island     

C.J.D. Adams 《Earth and Planetary Science Letters》1975,28(1):98-104

Rb-Sr whole-rock analyses yield a Cambro-Ordovician (495 ± 11 m.y.) sedimentation age for the supposed Precambrian Greenland Group and a late Precambrian age, 680 ± 21 m.y., for parts of the Constant Gneiss, the first confirmation of Precambrian rocks in New Zealand. A Precambrian age for the Greenland Group is thus unlikely and the large area of Upper Cambrian-Lower Ordovician rocks now established can be considered as a lateral equivalent of the fossiliferous Lower Palaeozoic succession of northwest Nelson to the east. The Greenland Group, especially in the Paparoa Range has been affected subsequently by a thermal metamorphic overprint about 360 m.y. ago during the Tuhuan Orogeny. Although the Constant Gneiss must form the local basement to the Greenland Group in north Westland, the former does not appear to be the source of the sediments and the true provenance must lie elsewhere.  相似文献   

A thermal tool for direct investigation of the interior of the earth     

Wm. Mansfield Adams 《Pure and Applied Geophysics》1965,61(1):113-122

Summary Direct access to the crust and the upper portion of the mantle may be achieved by letting a high temperature (>1100°C) reactor core melt the rock in which it is placed and fall through the resulting magma. Data gathering and retrieval seem feasible. A schematic design of the proposed instrument is given.There are many problems concerning the composition and conditions of the interior of the earth which will not be solved upon completion of the projectedMohole Project. Comparison of the continental crust with the oceanic crust, relative distribution of radioactivity under continents and oceans, and the investigation of the mantle itself require access to greater depths than the present drilling techniques permit. To achieve these aims, it is recommended that a dense, heatgenerating object (such as a nuclear reactor core) be placed in the top of a salt dome. The hot object would melt the salt and fall downward through the moten salt. The sinking object would pass out of the source salt bed into rock at such a depth, say 35 000 feet, that if a few percent of H₂O is present at that depth, then a granitic rock would melt at about 700°C. However, encounter with SiO₂ containing no water would require a much higher temperature of about 1700°C. The type of rock that actually exists immediately below the source salt bed is unknown, but it is probably not a granitic rock.Thermal considerations indicate that the hole will freeze shut after downward passage of the tool, leaving the tool inside a liquid bubble. If the tool can generate heat long enough to melt its way up, as well as down, it may be possible to obtain magma samples. Instrumentation for control and telemetry purposes appears extremely difficult. Initial emphasis is placed on attaining the depth of interest.  相似文献   

Evidence from U–Pb zircon and ⁴⁰Ar/³⁹Ar muscovite detrital mineral ages in metasandstones for movement of the Torlesse suspect terrane around the eastern margin of Gondwanaland     

C.J. Adams  M.E. Barley  I.R. Fletcher  & A.L. Pickard 《地学学报》1998,10(4):183-189

New U–Pb detrital zircon ages from Triassic metasandstones of the Torlesse Terrane in New Zealand are compared with ⁴⁰Ar/³⁹Ar muscovite data and together, reveal four main source components: (i) major, Triassic–Permian (210–270 Myr old) and (ii) minor, Permian–Carboniferous (280–350 Myr old) granitoids (recorded in zircon and muscovite data); (iii) minor, early middle Palaeozoic, metamorphic rocks, recorded mainly by muscovite, 420–460 Myr old, and (iv) minor, Late Precambrian–Cambrian igneous and metamorphic complexes, 480–570 Myr old, recorded by zircon only. There are also Proterozoic zircon ages with no clear grouping (580–1270 Myr). The relative absence of late Palaeozoic (350–420 Myr old) components excludes granitoid terranes in the southern Lachlan Fold Belt (Australia) and its continuation into North Victoria Land (East Antarctica) and Marie Byrd Land (West Antarctica) as a potential source for the Torlesse. The age data are compatible with derivation from granitoid terranes of the northern New England Orogen (and hinterland) in NE Australia. This confirms that the Torlesse Terrane of New Zealand is a suspect terrane, that probably originated at the NE Australian, Permian–Triassic, Gondwanaland margin and then (200–120 Ma) moved 2500 km southwards to its present New Zealand position by the Late Cretaceous (90 Ma). This sense of movement is analogous to that suggested for Palaeozoic Mesozoic terranes at the North American Pacific margin.  相似文献   

Hydrologic characteristics of lake‐ and stream‐side riparian wetted margins in the McMurdo Dry Valleys,Antarctica     

Melissa L. Northcott  Michael N. Gooseff  John E. Barrett  Lydia H. Zeglin  Cristina D. Takacs‐Vesbach  John Humphrey 《水文研究》2009,23(9):1255-1267

Water is a limiting factor for life in the McMurdo Dry Valleys (MDV), Antarctica. The active layer (seasonally thawed soil overlying permafrost) accommodates dynamic hydrological and biological processes for 10–16 weeks per year. Wetted margins (visually wetted areas with high moisture content) adjacent to lakes and streams are potential locations of great importance in the MDV because of the regular presence of liquid water, compared with the rest of the landscape where liquid water is rare. At 11 plots (four adjacent to lakes, seven adjacent to streams), soil particle size distribution, soil electrical conductivity, soil water content and isotopic signature, width of the wetted margin, and active layer thaw depth were characterised to determine how these gradients influence physicochemical properties that determine microbial habitat and biogeochemical cycling. Sediments were generally coarse‐grained in wetted margins adjacent to both lakes and streams. Wetted margins ranged from 1·04 to 11·01 m in average length and were found to be longer at lakeside sites than streamside. Average thaw depths ranged from 0·12 to 0·85 m, and were found to be deepest under lake margins. Lake margins also had much higher soil electrical conductivity, steeper topographic gradients, but more gradual soil moisture gradients than stream margins. Patterns of soil water δ¹⁸O and δD distribution indicate capillary action and evaporation from wetted margins; margin pore waters generally demonstrated isotopic enrichment with distance from the shore, indicating evaporation of soil water. Lake margin pore waters were significantly more negative in D_XS (D_XS = δD‐8δ¹⁸O) than streamside pore waters, indicating a longer history of evaporation there. Differences between lake and stream margins can be explained by the more consistent availability of water to lake margins than stream margins. Differences in margin characteristics between lakes and streams have important consequences for the microbial habitat of these margins and their functional role in biogeochemical cycling at these terrestrial–aquatic interfaces. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献