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981.
982.
D.?H.?PhillipsEmail author A.?O.?Thomas K.?Forde K.?Dickson S.?Plant G.?Norris B.?Bone R.?M.?Kalin 《Environmental Geology》2007,52(6):1117-1131
Volatile organic compound (VOC) contamination of subsurface geological material and groundwater was discovered on the Nortel
Monkstown industrial site, Belfast, Northern Ireland. The objectives of this study were to (1) investigate the characteristics
of the geological material and its influences on contaminated groundwater flow across the site using borehole logs and hydrological
evaluations, and (2) identify the contaminants and examine their distribution in the subsurface geological material and groundwater
using chemical analysis. This report focuses on the eastern car park (ECP) which was a former storage area associated with
trichloroethene (TCE) degreasing operations. This is where the greatest amount of volatile organic compounds (VOCs), particularly
TCE, were detected. The study site is on a complex deposit of clayey glacial till with discontinuous coarser grained lenses,
mainly silts, sands and gravel, which occur at 0.45–7.82 m below ground level (bgl). The lenses overall form an elongated
formation that acts as a small unconfined shallow aquifer. There is a continuous low permeable stiff clayey till layer beneath
the lenses that performs as an aquitard to the groundwater. Highest concentrations of VOCs, mainly TCE, in the geological
material and groundwater are in these coarser lenses at ∼4.5–7 m bgl. Highest TCE measurements at 390,000 μg L−1 for groundwater and at 39,000 μg kg−1 at 5.7 m for geological material were in borehole GA19 in the coarse lens zone. It is assumed that TCE gained entrance to
the subsurface near this borehole where the clayey till was thin to absent above coarse lenses which provided little retardation
to the vertical migration of this dense non-aqueous phase liquid (DNAPL) into the groundwater. However, TCE is present in
low concentrations in the geological material overlying the coarse lens zone. Additionally, VOCs appear to be associated with
poorly drained layers and in peat <3.0 m bgl in the ECP. Some indication of natural attenuation as VOCs degradation products
vinyl chloride (VC) and dichloromethane (DCM) also occur on the site. 相似文献
983.
Liquid Immiscibility and the Evolution of Basaltic Magma 总被引:9,自引:0,他引:9
Veksler Ilya V.; Dorfman Alexander M.; Borisov Alexander A.; Wirth Richard; Dingwell Donald B. 《Journal of Petrology》2007,48(11):2187-2210
This experimental study examines relationships between alternativeevolution paths of basaltic liquids (the so-called Bowen andFenner trends), and silicate liquid immiscibility. Syntheticanalogues of natural immiscible systems exhibited in volcanicglasses and melt inclusions were used as starting mixtures.Conventional quench experiments in 1 atm gas mixing furnacesproved unable to reproduce unmixing of ferrobasaltic melts,yielding instead either turbid, opalescent glasses, or crystallizationof tridymite and pyroxenes. In contrast, experiments involvingin situ high-temperature centrifugation at 1000g (g = 9·8m/s2) did yield macroscopic unmixing and phase separation. Centrifugationfor 3–4 h was insufficient to complete phase segregation,and resulted in sub-micron immiscible emulsions in quenchedglasses. For a model liquid composition of the Middle Zone ofthe Skaergaard intrusion at super-liquidus temperatures of 1110–1120°C,centrifugation produced a thin, silicic layer (64·5 wt%SiO2 and 7·4 wt% FeO) at the top of the main Fe-richglass (46 wt% SiO2 and 21 wt% FeO). The divergent compositionsat the top and bottom were shown in a series of static runsto crystallize very similar crystal assemblages of plagioclase,pyroxene, olivine, and Fe–Ti oxides. We infer from theseresults that unmixing of complex aluminosilicate liquids maybe seriously kinetically hampered (presumably by a nucleationbarrier), and thus conventional static experiments may not correctlyreproduce it. In the light of our centrifuge experiments, immiscibilityin the Skaergaard intrusion could have started already at thetransition from the Lower to the Middle Zone. Thus, magma unmixingmight be an important factor in the development of the Fe-enrichmenttrend documented in the cumulates of the Skaergaard LayeredSeries. KEY WORDS: liquid immiscibility; Skaergaard; layered intrusions; experimental petrology 相似文献
984.
VILLIGER SAMUEL; ULMER PETER; MUNTENER OTHMAR; THOMPSON ALAN BRUCE 《Journal of Petrology》2004,45(12):2369-2388
Two series of anhydrous experiments have been performed in anend-loaded piston cylinder apparatus on a primitive, mantle-derivedtholeiitic basalt at 1·0 GPa pressure and temperaturesin the range 10601330°C. The experimental data provideconstraints on phase equilibria, and solid and liquid compositionsalong the liquid line of descent of primary basaltic magmasdifferentiating in storage reservoirs located at the base ofthe continental crust. The first series are equilibrium crystallizationexperiments on a single basaltic bulk composition; the secondseries are fractionation experiments where near-perfect fractionalcrystallization was approached in a stepwise manner using 30°Ctemperature steps and starting compositions corresponding tothe liquid composition of the previous, higher-temperature glasscomposition. Liquids in the fractional crystallization experimentsevolve with progressive SiO2 increase from basalts to dacites,whereas the liquids in the equilibrium crystallization experimentsremain basaltic and display only a moderate SiO2 increase accompaniedby more pronounced Al2O3 enrichment. The principal phase equilibriacontrols responsible for these contrasting trends are suppressionof the peritectic olivine + liquid = opx reaction and earlierplagioclase saturation in the fractionation experiments comparedwith the equilibrium experiments. Both crystallization processeslead to the formation of large volumes of ultramafic cumulatesrelated to the suppression of plagioclase crystallization relativeto pyroxenes at high pressures. This is in contrast to low-pressurefractionation of tholeiitic liquids, where early plagioclasesaturation leads to the production of troctolites followed by(olivine-) gabbros at an early stage of differentiation. KEY WORDS: liquid line of descent; tholeiitic magmas; equilibrium crystallization; fractional crystallization 相似文献
985.
该文利用地基双频(22.235GHz(1.35cm)和35.3GHz(8mm))微波辐射计和热带降雨测量卫星微波成像仪(TRMM/TMI)两种被动微波遥感资料分别反演安徽寿县地区云中液态水含量,运用统计回归方法得到该地区云水含量的反演公式,揭示了该地区云中液态水含量存在一个阈值0.4mm,当云中液态水含量超过这一阈值时,该地区一般就会出现降水。在降水发生之前,水汽和云中液态水含量均会出现一个显著增加的过程,而在降水结束之后则会出现一个显著减少的过程。 相似文献
986.
In this paper, we investigated the effects of temperature, oxygen, antioxidants, and corn germ oil on the stability of astaxanthin from Haematococcus pluvialis under different storage conditions, and changes in the composition of astaxanthin esters during storage using high performance liquid chromatography and spectrophotometry. Oxygen and high temperatures (22-25~C) significantly reduced the stability of astaxanthin esters. Corn germ oil and antioxidants (ascorbic acid and vitamin E) failed to protect astaxanthin from oxidation, and actually significantly increased the instability of astaxanthin. A change in the relative composition of astaxanthin esters was observed after 96 weeks of long-term storage. During storage, the relative amounts of free astaxanthin and astaxanthin monoesters declined, while the relative amount of astaxanthin diesters increased. Thus, the ratio of astaxanthin diester to monoester increased, and this ratio could be used to indicate if astaxanthin esters have been properly preserved. If the ratio is greater than 0.2, it suggests that the decrease in astaxanthin content could be higher than 20%. Our results show that storing algal powder from H. pluvialis or other natural astaxanthin products under vacuum and in the dark below 4~C is the most economical and applicable storage method for the large-scale production of astaxanthin from H. pluvialis. This storage method can produce an astaxanthin preservation rate of at least 80% after 96 weeks of storage. 相似文献
987.
A complete and accurate simulation of two‐phase flow in porous media requires knowledge of all the controlling physics (and values of physical parameters) that play a relevant role and an understanding of the effects of each one on the solution. Of particular concern here is the effect of capillary pressure and the length scale over which it is relevant. The goal of this paper is to provide guidance onto when to include the effects of capillary pressure in the model, and onto what are the resulting length scale restrictions if those effects are to be included. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
988.
Uncertainty of snow water equivalent retrieved from AMSR‐E brightness temperature in northeast Asia 下载免费PDF全文
Accurate estimation of snow water equivalent (SWE) has been significantly recognized to improve management and analyses of water resource in specific regions. Although several studies have focused on developing SWE values based on remotely sensed brightness temperatures obtained by microwave sensor systems, it is known that there are still a number of uncertainties in SWE values retrieved from microwave radiometers. Therefore, further research for improving remotely sensed SWE values including global validation should be conducted in unexplored regions such as Northeast Asia. In this regard, we evaluated SWE through comparison of values produced by the Advanced Microwave Scanning Radiometer Earth Observing System (AMSR‐E) from December 2002 to February 2011 with in situ SWE values converted from snow‐depth observation data from four regions in the South Korea. The results from three areas showed similarities which indicated that the AMSR‐E SWE values were overestimated when compared with in situ SWE values, and their Mean Absolute Errors (MAE) by month were relatively small (1.1 to 6.5 mm). Contrariwise, the AMSR‐E SWE values of one area were significantly underestimated when compared with in situ SWE values and the MAE were much greater (4.9 to 35.2 mm). These results were closely related to AMSR‐E algorithm‐related error sources, which we analyzed with respect to topographic characteristics and snow properties. In particular, we found that snow density data used in the AMSR‐E SWE algorithm should be based on reliable in situ data as the current AMSR‐E SWE algorithm cannot reflect the spatio‐temporal variability of snow density values. Additionally, we derived better results considering saturation effect of AMSR‐E SWE. Despite the demise of AMSR‐E, this study's analysis is significant for providing a baseline for the new sensor and suggests parameters important for obtaining more reliable SWE. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
989.
Evaluation of a surface energy balance method based on optical and thermal satellite imagery to estimate root‐zone soil moisture 下载免费PDF全文
Various remote‐sensing methods are available to estimate soil moisture, but few address the fine spatial resolutions (e.g. 30‐m grid cells) and root‐zone depth requirements of agricultural and other similar applications. One approach that has been previously proposed to estimate fine‐resolution soil moisture is to first estimate the evaporative fraction from an energy balance that is inferred from optical and thermal remote‐sensing images [e.g. using the Remote Sensing of Evapotranspiration (ReSET) algorithm] and then estimate soil moisture through an empirical relationship to evaporative fraction. A similar approach has also been proposed to estimate the degree of saturation. The primary objective of this study is to evaluate these methods for estimating soil moisture and degree of saturation, particularly for a semi‐arid grassland with relatively dry conditions. Soil moisture was monitored at 28 field locations in south‐eastern Colorado with herbaceous vegetation during the summer months of 3 years. In situ soil moisture and degree of saturation observations are compared with estimates calculated from Landsat imagery using the ReSET algorithm. The in situ observations suggest that the empirical relationships with evaporative fraction that have been proposed in previous studies typically provide overestimates of soil moisture and degree of saturation in this region. However, calibrated functions produce estimates with an accuracy that may be adequate for various applications. The estimates produced by this approach are more reliable for degree of saturation than for soil moisture, and the method is more successful at identifying temporal variability than spatial variability in degree of saturation for this region. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
990.