Geochemical Reactions During Biodegradation/Vapor-Extraction Remediation of Petroleum Contamination in the Vadose Zone     

Regina M. Capuano  Mark A. Johnson 《Ground water》1996,34(1):31-40

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Origin of Dissolved Organic Carbon Studied by UV‐vis Spectroscopy     

Snia Regina Giancoli Barreto  Jorge Nozaki  Wagner J. Barreto 《洁净——土壤、空气、水》2003,31(6):513-518

Dissolved organic carbon (DOC) distributions in water from Lake Ipê, MS, Brazil, were investigated. The samplings were performed monthly (surface, 1 m depth, and bottom) from June 1999 to June 2000. Absorbance at 285 nm and DOC concentrations in mg dm^—3, p(DOC), were highly correlated for the three depths. 77% of the surface, 85% for 1 m and bottom samples presented a variation between 20 dm³ g^—1 cm^—1 and 50 dm³ g^—1 cm^—1 of A(285 nm)/p(DOC), that characterizes the dissolved organic matter in lake water as essentially fulvic. The ratio A(254 nm)/p(DOC) was also sensitive for fulvic matter, and an A(250 nm)/A(365 nm) = 4 ratio was characteristic of strongly colored waters. The ratios A(436 nm)/p(DOC) for the three depths also showed a significant correlation. The predominance of fulvic acid is explained by environmental characteristics such as the tropical climate, temperatures above 18 °C, and the lake environment. It was demonstrated that the variation in the water carbon content due to different compartments in the lake can be monitored by UV‐vis spectroscopy ratios.  相似文献   

Hydrogen isotope fractionation factor for mixed-layer illite/smectite at 60° to 150°C: new data from the northeast Texas Gulf Coast     

Kiseong Hyeong  Regina M. Capuano 《Geochimica et cosmochimica acta》2004,68(7):1529-1543

The δD values of water and clay collected from 0.6 to 5.5 km deep wells in 9 oil and gas fields within the Houston salt basin located in the northeast Texas Gulf Coast were used to reevaluate the temperature dependence of hydrogen isotope fractionation between mixed layer illite/smectite (I/S) and water, and the equations of Yeh (1980), Geochim. Cosmochim. Acta, 42:140-143) and Capuano (1992), Geochim. Cosmochim. Acta, 56:2547-2554) for the calculation of αI/S-water, both of which are commonly cited in the literature. δD values of water and clay in the normally pressured and geopressured sections are different. In the normally pressured section (<2.6 km), δD_water is constant (−15 ± 1 (1σ)‰) while δD_clay increases linearly from −59 to −43‰ with increasing depth. In contrast, in the geopressured section δD_water decreases linearly from −7 to −26‰ with increasing depth while δD_clay is nearly constant (−36 ± 3 (1σ)‰). The opposite trends are a product of D/H exchange between clay and water in a water-dominated system within the normally pressured section and rock-dominated system in the geopressured section. Assuming hydrogen isotope equilibrium between sediments and enclosed pore water, the new δD_water and δD_clay data were used to calculate the hydrogen isotope fractionation factor between I/S and water (αI/S-water), which showed a good fit to the equation derived by Capuano (1992), but not to the equation derived by Yeh (1980), both for the normally and geopressured data despite that both data sets are strikingly different. This suggests that hydrogen isotope equilibrium has been achieved in these two different regimes and that the equation by Capuano (1992) is valid and has wider applicability.  相似文献   

Secondary Ca–Al silicates in plutonic rocks: implications for their cooling history     

Regina Freiberger  Lutz Hecht  Michel Cuney  Giulio Morteani 《Contributions to Mineralogy and Petrology》2001,141(4):415-429

Secondary Ca-Al silicates are used to constrain the P-T-x conditions of the very early post-magmatic stage of the intermediate to basic Hercynian plutonic complexes of Charroux-Civray (NW Massif Central, France) and Fichtelgebirge (NE Bavaria, Germany). The secondary Ca-Al silicates hydrogarnet, prehnite, pumpellyite, epidote and laumontite form lenses within unaltered or only slightly chloritized biotite. Hydrogarnet as the first occurring Ca-Al silicate phase crystallizes at temperatures above 340 °C. The common paragenesis prehnite + pumpellyite post-dates hydrogarnet and indicates rather narrow ranges of temperature (200-280 °C) and pressure (2-3 kbar). Laumontite is formed at the end of Ca-Al silicate crystallization (180-260 °C, 1-3 kbar), mostly in small fractures in association with prehnite and adularia. The observed crystallization sequence of the Ca-Al silicates and their stabilities define a retrograde alteration path for the plutonic rocks. The Ca-Al silicate assemblage results from an early pervasive alteration of the plutonic rocks by low X_CO2 fluids during post-magmatic cooling. Subsolidus cooling starts at about 4 kbar at solidus temperatures as indicated by magmatic epidote stability, hornblende barometry and fluid inclusion data, and continues under slightly decreasing pressure (uplift) down to 2-3 kbar at 200-280 °C (prehnite-pumpellyite paragenesis). This shows that Ca-Al silicate assemblages may be a unique tool to constrain the P-T conditions of the subsolidus cooling of intermediate to basic plutonic bodies.  相似文献   

Bioassay‐directed fractionation for analyzing estrogens in surface waters of the German Baltic Sea     

Iris‐Constanze Beck  Regina Bruhn  Juergen Gandrass 《洁净——土壤、空气、水》2006,34(6):560-567

A reversed‐phase fractionation method with subsequent biological and chemical analysis has been developed to estimate the contributions of the most potent estrogens to observed estrogenic effect potentials. Surface water samples were taken in the German Baltic Sea (Inner Wismar Bay and Darss Peninsula, sampling campaign July 2003) and were separated into seven individual fractions. Three fractions showed significant estrogenic activities and clear dose‐dependant responses were obtained in the yeast estrogen screen (YES). In the 2nd fractions liquid chromatographic‐electrospray‐tandem mass spectrometric (LC‐ESI‐MS‐MS) analyses showed the presence of bisphenol A (Inner Wismar Bay: 4.8 ng L^–1 and 6 ng L^–1; Darss Peninsula: 0.91 ng L^–1 and 1.7 ng L^–1) and ethinylestradiol (Inner Wismar Bay: 2.0 ng L^–1 and 6.0 ng L^–1; Darss Peninsula: < MDL and 1.7 ng L^–1), whereas estrogenic activities in the YES were only around 10% of the positive control E2. Although not identified prior in the total extract the natural hormones estradiol (Inner Wismar Bay: 0.13 ng L^–1 and 0.19 ng L^–1; Darss Peninsula: 0.12 ng L^–1 and 0.16 ng L^–1) and estriol (Inner Wismar Bay: < MDL and 0.33 ng L^–1; Darss Peninsula: < MDL) could be detected in the 3rd fractions, where high estrogenic potentials could be observed. The 4th fractions showed high responses as well and estrone were herein quantified with concentrations of 0.16 ng L^–1 and 0.18 ng L^–1 (Darss Peninsula) up to 0.37 ng L^–1 (Inner Wismar Bay). Measured and calculated estradiol equivalents for individual fractions correlated very well (R² = 0.78), when disregarding results of the 2nd fraction, where high deviations occurred.  相似文献   

Probabilities in climate policy advice: a critical comment     

Gregor Betz 《Climatic change》2007,85(1-2):1-9

This essay explores as to whether probabilistic climate forecasting is consistent with the prerequisites of democratic scientific policy advice. It argues that, given the boundaries of our current knowledge, it is highly problematic to assign exact, unconditional probabilities to possible values of climate sensitivity. The range of possible–instead of probable–future climate scenarios is what climate policy should be based on.  相似文献   

Future extreme events in European climate: an exploration of regional climate model projections   总被引：7，自引：0，他引：7  

Martin Beniston  David B. Stephenson  Ole B. Christensen  Christopher A. T. Ferro  Christoph Frei  Stéphane Goyette  Kirsten Halsnaes  Tom Holt  Kirsti Jylhä  Brigitte Koffi  Jean Palutikof  Regina Schöll  Tido Semmler  Katja Woth 《Climatic change》2007,81(1):71-83

This paper compares how well satellite versus weather station measurements of climate predict agricultural performance in Brazil, India, and the United States. Although weather stations give accurate measures of ground conditions, they entail sporadic observations that require interpolation where observations are missing. In contrast, satellites have trouble measuring some ground phenomenon such as precipitation but they provide complete spatial coverage of various parameters over a landscape. The satellite temperature measurements slightly outperform the interpolated ground station data but the precipitation ground measurements generally outperform the satellite surface wetness index. In India, the surface wetness index outperforms station precipitation but this may be reflecting irrigation, not climate. The results suggest that satellites provide promising measures of temperature but that ground station data may still be preferred for measuring precipitation in rural settings.  相似文献   

GGR Critical Review of Analytical Developments in 2008–2009: An Introduction     

Janet M. Hergt  Ricardo Arevalo Jr  L. Paul Bèdard  Jeremy Bellucci  Jacinta Enzweiler  Klaus Peter Jochum  Kathryn L. Linge  William F. McDonough  Regina Mertz-Kraus  Michael Wiedenbeck  Xiaohong Wang  Jon D. Woodhead 《Geostandards and Geoanalytical Research》2010,34(4):325-326

This collection of articles represents the fourth in a series of reviews in which authors have aimed at capturing the key advances in a range of analytical fields ( Hergt et al. 2005, 2006, 2008 ). The publication period under review is 2008–2009 and the intention here is to provide readers with a summary of the most influential developments published during this period, across a broad range of topics appropriate to the Earth and environmental sciences. Most authors comment on the ways in which the emphases of research in their specific fields of examination have changed over time. All note an increase in rigour and focus on data quality. Whether advances have taken place in instrumentation, sample manipulation or data deconvolution, there are a large number of dedicated scientists out there contributing to the high quality of geochemical data employed in geological and environmental research.  相似文献   

Employing turbulent and meandering time scales to modeling the contaminants enhanced horizontal dispersion     

Andra Ucker Timm  Gervsio Annes Degrazia  Dbora Regina Roberti  Domenico Anfossi 《Atmospheric Research》2009,93(4):811-817

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Attitude stability of artificial satellites subject to gravity gradient torque     

Rodolpho Vilhena de Moraes  Regina Elaine Santos Cabette  Maria Cecília Zanardi  Teresinha J. Stuchi  Jorge Kennety Formiga 《Celestial Mechanics and Dynamical Astronomy》2009,104(4):337-353

The stability of the rotational motion of artificial satellites is analyzed considering perturbations due to the gravity gradient torque, using a canonical formulation, and Andoyer’s variables to describe the rotational motion. The stability criteria employed requires the reduction of the Hamiltonian to a normal form around the stable equilibrium points. These points are determined through a numerical study of the Hamilton’s equations of motion and linear study of their stability. Subsequently a canonical linear transformation is used to diagonalize the matrix associated to the linear part of the system resulting in a normalized quadratic Hamiltonian. A semi-analytic process of normalization based on Lie–Hori algorithm is applied to obtain the Hamiltonian normalized up to the fourth order. Lyapunov stability of the equilibrium point is performed using Kovalev and Savchenko’s theorem. This semi-analytical approach was applied considering some data sets of hypothetical satellites, and only a few cases of stable motion were observed. This work can directly be useful for the satellite maintenance under the attitude stability requirements scenario.  相似文献