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91.
Delineation of groundwater protection zones by the backward particle tracking method: theoretical background and GIS-based stochastic analysis 总被引:1,自引:0,他引:1
Konstadinos N. Moutsopoulos Alexandra Gemitzi Vassilios A. Tsihrintzis 《Environmental Geology》2008,54(5):1081-1090
The backward particle tracking method, an effective and powerful tool that can be used to delineate groundwater protection
zones, is presented. The theoretical background and insights on the applicability of this method are provided. Moreover, the
present work enriches the backward particle tracking method with an uncertainty analysis concerning the porosity values, applying
a Monte Carlo (MC) approach, coupled with the use of geographical information systems (GIS). As an application example, a
wellfield in the Komotini area, Greece, is investigated. The present study may serve as a potential guideline for wellfield
delineation, particularly in areas like Greece where lack of data related to the hydrogeological system is often a problem. 相似文献
92.
The largest karst cave discovered in a tunnel during motorway construction in Slovenia’s Classical Karst (Kras) 总被引:1,自引:0,他引:1
Karst researchers of the Karst Research Institute ZRC SAZU are regularly consulted during the planning of Slovenia’s motorways
and invited to observe and monitor construction in the karst areas. More than 350 caves have been discovered in the course
of building 60 km of new motorways over the past decade. Access to the most important caves is preserved by concrete tubes
closed with metal covers at the roadside. The largest cave system in a tunnel, named LC-S647, is almost entirely preserved.
The protection of this cave will serve as a good example for the preservation of natural heritage in the future. Construction
work for the motorway uncovered a high degree of karstification. In particular, the discovery of this cave in the Kastelec
tunnel LC-S647 showed the existence of a major cave system in the geological and speleological past. A number of unconnected
passages have also been found. Caves discovered during highway construction have brought new knowledge about the cavernosity
and the geological history of this part of the karst. 相似文献
93.
Correlations between heavy metals and organic carbon extracted by dry oxidation procedure in urban roadside soils 总被引:1,自引:0,他引:1
Xue Song Wang 《Environmental Geology》2008,54(2):269-273
The organic fraction in soils has a significant influence on heavy metal transport. In this study, the organic carbon content
was measured by dry oxidation procedure from 21 Xuzhou urban roadside soils to assess the relationships between the concentrations
of heavy metals (Pb, Cu, Zn, and Cr) and the amount of organic carbon. The anthropogenic heavy metals (e.g. Pb, Cu, Zn) were
strongly correlated with organic carbon (denoted by Corg−c) extracted by dry oxidation while natural heavy metal (e.g. Cr) showed no correlation to the Corg−c. The anthropogenic heavy metals were also strongly correlated with the amount of the total carbon. These results show that
the anthropogenic heavy metals are mainly enriched in the organic matter in the Xuzhou urban roadside soils. 相似文献
94.
Landslide susceptibility mapping for a landslide-prone area (Findikli,NE of Turkey) by likelihood-frequency ratio and weighted linear combination models 总被引:17,自引:0,他引:17
Landslides are very common natural problems in the Black Sea Region of Turkey due to the steep topography, improper use of
land cover and adverse climatic conditions for landslides. In the western part of region, many studies have been carried out
especially in the last decade for landslide susceptibility mapping using different evaluation methods such as deterministic
approach, landslide distribution, qualitative, statistical and distribution-free analyses. The purpose of this study is to
produce landslide susceptibility maps of a landslide-prone area (Findikli district, Rize) located at the eastern part of the
Black Sea Region of Turkey by likelihood frequency ratio (LRM) model and weighted linear combination (WLC) model and to compare
the results obtained. For this purpose, landslide inventory map of the area were prepared for the years of 1983 and 1995 by
detailed field surveys and aerial-photography studies. Slope angle, slope aspect, lithology, distance from drainage lines,
distance from roads and the land-cover of the study area are considered as the landslide-conditioning parameters. The differences
between the susceptibility maps derived by the LRM and the WLC models are relatively minor when broad-based classifications
are taken into account. However, the WLC map showed more details but the other map produced by LRM model produced weak results.
The reason for this result is considered to be the fact that the majority of pixels in the LRM map have high values than the
WLC-derived susceptibility map. In order to validate the two susceptibility maps, both of them were compared with the landslide
inventory map. Although the landslides do not exist in the very high susceptibility class of the both maps, 79% of the landslides
fall into the high and very high susceptibility zones of the WLC map while this is 49% for the LRM map. This shows that the
WLC model exhibited higher performance than the LRM model. 相似文献
95.
Quick-look assessments to identify optimal CO2 EOR storage sites 总被引:1,自引:0,他引:1
Vanessa Núñez-López Mark H. Holtz Derek J. Wood William A. Ambrose Susan D. Hovorka 《Environmental Geology》2008,54(8):1695-1706
A newly developed, multistage quick-look methodology allows for the efficient screening of an unmanageably large number of
reservoirs to generate a workable set of sites that closely match the requirements for optimal CO2 enhanced oil recovery (EOR) storage. The objective of the study is to quickly identify miscible CO2 EOR candidates in areas that contain thousands of reservoirs and to estimate additional oil recovery and sequestration capacities
of selected top options through dimensionless modeling and reservoir characterization. Quick-look assessments indicate that
the CO2 EOR resource potential along the US Gulf Coast is 4.7 billion barrels, and CO2 sequestration capacity is 2.6 billion metric tons. In the first stage, oil reservoirs are screened and ranked in terms of
technical and practical feasibility for miscible CO2 EOR. The second stage provides quick estimates of CO2 EOR potential and sequestration capacities. In the third stage, a dimensionless group model is applied to a selected set
of sites to improve the estimates of oil recovery and storage potential using appropriate inputs for rock and fluid properties,
disregarding reservoir architecture and sweep design. The fourth stage validates and refines the results by simulating flow
in a model that describes the internal architecture and fluid distribution in the reservoir. The stated approach both saves
time and allows more resources to be applied to the best candidate sites. 相似文献
96.
On CO<Subscript>2</Subscript> fluid flow and heat transfer behavior in the subsurface,following leakage from a geologic storage reservoir 总被引:1,自引:0,他引:1
Karsten Pruess 《Environmental Geology》2008,54(8):1677-1686
Geologic storage of CO2 is expected to produce plumes of large areal extent, and some leakage may occur along fractures, fault zones, or improperly
plugged pre-existing wellbores. A review of physical and chemical processes accompanying leakage suggests a potential for
self-enhancement. The numerical simulations presented here confirm this expectation, but reveal self-limiting features as
well. It seems unlikely that CO2 leakage could trigger a high-energy run-away discharge, a so-called “pneumatic eruption,” but present understanding is insufficient
to rule out this possibility. The most promising avenue for increasing understanding of CO2 leakage behavior is the study of natural analogues. 相似文献
97.
Curtis M. Oldenburg 《Environmental Geology》2008,54(8):1687-1694
A screening and ranking framework (SRF) has been developed to evaluate potential geologic carbon dioxide (CO2) storage sites on the basis of health, safety, and environmental (HSE) risk arising from CO2 leakage. The approach is based on the assumption that CO2 leakage risk is dependent on three basic characteristics of a geologic CO2 storage site: (1) the potential for primary containment by the target formation; (2) the potential for secondary containment
if the primary formation leaks; and (3) the potential for attenuation and dispersion of leaking CO2 if the primary formation leaks and secondary containment fails. The framework is implemented in a spreadsheet in which users
enter numerical scores representing expert opinions or published information along with estimates of uncertainty. Applications
to three sites in California demonstrate the approach. Refinements and extensions are possible through the use of more detailed
data or model results in place of property proxies. 相似文献
98.
Laura Chiaramonte Mark D. Zoback Julio Friedmann Vicki Stamp 《Environmental Geology》2008,54(8):1667-1675
This paper reports a preliminary investigation of CO2 sequestration and seal integrity at Teapot Dome oil field, Wyoming, USA, with the objective of predicting the potential risk
of CO2 leakage along reservoir-bounding faults. CO2 injection into reservoirs creates anomalously high pore pressure at the top of the reservoir that could potentially hydraulically
fracture the caprock or trigger slip on reservoir-bounding faults. The Tensleep Formation, a Pennsylvanian age eolian sandstone
is evaluated as the target horizon for a pilot CO2 EOR-carbon storage experiment, in a three-way closure trap against a bounding fault, termed the S1 fault. A preliminary geomechanical
model of the Tensleep Formation has been developed to evaluate the potential for CO2 injection inducing slip on the S1 fault and thus threatening seal integrity. Uncertainties in the stress tensor and fault
geometry have been incorporated into the analysis using Monte Carlo simulation. The authors find that even the most pessimistic
risk scenario would require ∼10 MPa of excess pressure to cause the S1 fault to reactivate and provide a potential leakage
pathway. This would correspond to a CO2 column height of ∼1,500 m, whereas the structural closure of the Tensleep Formation in the pilot injection area does not exceed
100 m. It is therefore apparent that CO2 injection is not likely to compromise the S1 fault stability. Better constraint of the least principal stress is needed to
establish a more reliable estimate of the maximum reservoir pressure required to hydrofracture the caprock. 相似文献
99.
Wenjun Yong E. Dachs A. C. Withers E. J. Essene 《Contributions to Mineralogy and Petrology》2008,155(2):137-146
The low-temperature heat capacity (C
p) of Si-wadeite (K2Si4O9) synthesized with a piston cylinder device was measured over the range of 5–303 K using the heat capacity option of a physical
properties measurement system. The entropy of Si-wadeite at standard temperature and pressure calculated from the measured
heat capacity data is 253.8 ± 0.6 J mol−1 K−1, which is considerably larger than some of the previous estimated values. The calculated phase transition boundaries in the
system K2O–Al2O3–SiO2 are generally consistent with previous experimental results. Together with our calculated phase boundaries, seven multi-anvil
experiments at 1,400 K and 6.0–7.7 GPa suggest that no equilibrium stability field of kalsilite + coesite intervenes between
the stability field of sanidine and that of coesite + kyanite + Si-wadeite, in contrast to previous predictions. First-order
approximations were undertaken to calculate the phase diagram in the system K2Si4O9 at lower pressure and temperature. Large discrepancies were shown between the calculated diagram compared with previously
published versions, suggesting that further experimental or/and calorimetric work is needed to better constrain the low-pressure
phase relations of the K2Si4O9 polymorphs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
100.
H2O-undersaturated melting experiments of synthesized basalt (SiO2 = 50.7 wt.%, MgO = 8.3 wt.%, Mg# = 60) were conducted at fO2 corresponding to NNO+1 and NNO−1 to clarify the effects of pressure (2–7 kbar) and H2O on fractional crystallization in island arcs. H2O content was ranged from nominally anhydrous to 4.4 wt.%. Differentiation trends, namely the liquid lines of descent, change
sensitively according to pressure-H2O relations. Tholeiitic differentiation trends are reproduced with H2O ≤ ∼2 wt.% in primary magma. With such quantities of H2O, fractional crystallization is controlled by olivine + plagioclase at 2 kbar. Increasing the pressure from 2 to ≥4 kbar
induces early crystallization of orthopyroxene instead of olivine and therefore SiO2 enrichment in the residual melts is suppressed. Increasing H2O (≥ ∼2 wt.% in primary magma) stabilizes clinopyroxene relative to orthopyroxene and/or magnetite. Although the phase relations
and proportions strongly depend on fO2 and H2O content, differentiation trends are always calc-alkaline. 相似文献