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排序方式: 共有161条查询结果,搜索用时 46 毫秒
91.
Optimizing the Environmental Performance of In Situ Thermal Remediation Technologies Using Life Cycle Assessment 总被引:3,自引:0,他引:3
Gitte Lemming Steffen G. Nielsen Klaus Weber Gorm Heron Ralph S. Baker Jacqueline A. Falkenberg Mads Terkelsen Carsten B. Jensen Poul L. Bjerg 《Ground Water Monitoring & Remediation》2013,33(3):38-51
In situ thermal remediation technologies provide efficient and reliable cleanup of contaminated soil and groundwater, but at a high cost of environmental impacts and resource depletion due to the large amounts of energy and materials consumed. This study provides a detailed investigation of four in situ thermal remediation technologies (steam enhanced extraction, thermal conduction heating, electrical resistance heating, and radio frequency heating) in order to (1) compare the life‐cycle environmental impacts and resource consumption associated with each thermal technology, and (2) identify options to reduce these adverse effects. The study identifies a number of options for environmental optimization of in situ thermal remediation. In general, environmental optimization can be achieved by increasing the percentage of heating supplied in off peak electricity demand periods as this reduces the pressure on coal‐based electricity and thereby reduces the environmental impacts due to electricity production by up to 10%. Furthermore, reducing the amount of concrete in the vapor cap by using a concrete sandwich construction can potentially reduce the environmental impacts due to the vapor cap by up to 75%. Moreover, a number of technology‐specific improvements were identified, for instance by the substitution of stainless steel types in wells, heaters, and liners used in thermal conduction heating, thus reducing the nickel consumption by 45%. The combined effect of introducing all the suggested improvements is a 10 to 21% decrease in environmental impacts and an 8 to 20% decrease in resource depletion depending on the thermal remediation technology considered. The energy consumption was found to be the main contributor to most types of environmental impacts; this will, however, depend on the electricity production mix in the studied region. The combined improvement potential is therefore to a large extent controlled by the reduction/improvement of energy consumption. 相似文献
92.
93.
Jacqueline Malarkey Nadine Wittig D. Graham Pearson Jon P. Davidson 《Contributions to Mineralogy and Petrology》2011,162(2):289-302
Clinopyroxene is a major host for lithophile elements in the mantle lithosphere, and therefore it is critical whether we are
to understand the constraints that this mineral puts on mantle evolution and melt generation. This study presents a detailed
in situ trace element and Sr isotope study of clinopyroxene, amphibole and melt from two spinel lherzolites from the Middle
Atlas Mountains, Morocco. The results show that there is limited, but discernable, Sr isotopic variation between clinopyroxene
crystals within these xenoliths [87Sr/86Sr ranging from 0.703416 (±11 2SE) to 0.703681 (±12 2SE)]. Trace element patterns show similar interelement fractionation
with LREE enrichment, but there is a considerable range in terms of elemental concentration (e.g. over 100 ppm in Sr concentrations).
Observed modal clinopyroxene is far more abundant than that predicted from estimates of melt depletion. This along with isotope
and trace element variability found in these xenoliths supports a multistage metasomatic process in which clinopyroxene and
amphibole are recent secondary additions to the lithospheric mantle. Elemental systematics indicate that the metasomatic mineral
assemblage has most recently equilibrated with a carbonatitic melt prior to inclusion in the host basalt. The clinopyroxene
from this study is typical of global off-craton clinopyroxene in terms of Sr isotope composition, suggesting that the majority
of clinopyroxene in off-craton settings may have a recent metasomatic origin. These findings indicate that caution is required
when using peridotite xenoliths to estimate the degree of elemental enrichment in the subcontinental lithosphere. 相似文献
94.
Nara Somaratne Keith Smettem Jacqueline Frizenschaf 《Environmental Earth Sciences》2014,72(6):2141-2151
There is a broad variety of methods to estimate groundwater recharge, but tools to assess the reliability of particular methods are not available. This paper introduces three distinct criteria to assess the reliability of recharge: applicability of the method used, availability of reliable data, and spatial coverage. Weightings of each criterion are assigned using key attributes present to total attributes required under each criterion. A reliability assessment was applied to two point-recharge and two diffuse-recharge dominated groundwater basins in South Australia. We show that the use of groundwater age based on chlorofluorocarbon and the conventional chloride mass balance method gives unreliable estimates of recharge in karstic aquifers, primarily due to inappropriate assumptions concerning the nature of recharge in these systems. Among the methods evaluated, watertable fluctuation, numerical groundwater modelling, Darcy flow calculation and the water budget method are applied to both point and diffuse recharge dominant groundwater basins. The reliability of these methods depends primarily on the quality of data and spatial coverage of the basin. Once the reliability level is known, water resources planners and managers assess the level of risk to aquifers, the environment, and the socio-economic development required for sustainable management of groundwater. 相似文献
95.
New observations of the planetary nebula A 79 using selective interference filters (Δ λ ≤ 10 Å) are reported. Thanks to the large field of view (< 11″5) offered by the Observatoire de Haute Provence 120-cm telescope we were able to discover a new extended feature close to A 79. 相似文献
96.
Andrew J. Walsh Jacqueline F. Chapman Michael G. Burton Mark Wardle T. J. Millar 《Monthly notices of the Royal Astronomical Society》2007,380(4):1703-1714
We report on Australia Telescope Compact Array observations of the massive star-forming region G305.2+0.2 at 1.2 cm. We detected emission in five molecules towards G305A, confirming its hot core nature. We determined a rotational temperature of 26 K for methanol. A non-local thermodynamic equilibrium excitation calculation suggests a kinematic temperature of the order of 200 K. A time-dependent chemical model is also used to model the gas-phase chemistry of the hot core associated with G305A. A comparison with the observations suggest an age of between 2 × 104 and 1.5 × 105 yr . We also report on a feature to the south-east of G305A which may show weak Class I methanol maser emission in the line at 24.933 GHz. The more evolved source G305B does not show emission in any of the line tracers, but strong Class I methanol maser emission at 24.933 GHz is found 3 arcsec to the east. Radio continuum emission at 18.496 GHz is detected towards two H ii regions. The implications of the non-detection of radio continuum emission towards G305A and G305B are also discussed. 相似文献
97.
Janina Wiszniewska Stefan Claesson Holly Stein Jacqueline Vander Auwera Jean-Clair Duchesne 《地学学报》2002,14(6):451-460
ABSTRACT Deeply buried 1.5 Ga Polish anorthosites, accessible only by bore holes, reveal diagnostic features of some massif-type anorthosites (polybarism, jotunitic parent magma), diapirically emplaced in the mid crust together with the rapakivi granites of the EW-trending Mazury complex, intruded along a major crustal discontinuity. Geochemical modelling and isotope data corroborate recent experimental work on the basaltic system in dry conditions: the source rock of the parental magma is a gabbronorite, necessarily lying in the lower crust. Since no Archaean crust is known in the region, high initial 188 Os/187 Os ratios for sulphide-oxide isochrons and negative εNd values are best accounted for by melting a ∼ 2.0 Ga mafic crust. 相似文献
98.
99.
The FeOOH phase in Apollo 16 rocks is akaganéite. Other polymorphs of FeOOH, i.e. geothite and lepidocrocite, may exist but have not been identified by X-ray diffraction. Experiments performed during this study using akaganéite, geothite, and lepidocrocite placed at 135°C and under a pumping vacuum of 10?2 torr, demonstrate that these forms of FeOOH are not stable on the surface of the Moon, where daytime temperatures are about 140°C and pressures are about 10?7 torr. The effect of the vacuum is to strip off the water, and the temperature speeds up this dehydration process. These data lend support to the contention of Taylor et al. (1973) that the FeOOH in lunar rocks formed by the oxyhydration of lawrencite, FeCl2, due to contamination by terrestrial water vapor. 相似文献
100.
Bastiaan Wijnand Borsje Suzanne Jacqueline Marie Hélène Hulscher Peter Maria Jozef Herman Mindert Bareld de Vries 《Ocean Dynamics》2009,59(5):659-670
The bed of the North Sea is covered by sand waves and houses a great number of macrobenthic animals. These bio-engineers are
known to have a significant influence on the stability of the bed and thereby on the geomorphology of the seabed. This paper
proposes a parameterization of these bio-geomorphological interactions. Given the abundance of three dominant bio-engineers
on the Dutch Continental Shelf, the predicted occurrence of sand waves, in which the parameterization is included, shows significantly
better results, compared to the prediction for the default case without biology. Therefore, the inclusion of biological activity
could be important to predict the occurrence of sand waves. 相似文献