Absorption and fluorescence properties of rainwater during the cold season at a town in Western Portugal   总被引：1，自引：0，他引：1  

Patrícia S. M. Santos  Regina M. B. O. Duarte  Armando C. Duarte 《Journal of Atmospheric Chemistry》2009,62(1):45-57

This study aims at evaluating the variability of the optical properties of chromophoric dissolved organic matter (CDOM) of rainwater during the cold season, specifically between Autumn and Winter periods. The spectroscopic characteristics of rainwater samples collected at a town (Aveiro) in western Portugal were assessed by UV-Vis absorbance and three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopies. Rainwater samples showed similar characteristics to those of natural humic substances when analysed by UV-Vis absorbance spectroscopy, but a significant difference was observed in the volume weight average (VWA) of absorbances between Autumn and Winter. In general, the EEM fluorescence spectra of the Autumn and Winter samples disclosed the presence of six fluorophores with different VWA specific fluorescence intensities: three humic-like (λ _excitation/λ _emission ≈ 230/415 nm; 290/415 nm; and 340/415 nm) and three protein-like (λ _excitation/λ _emission ≈ 230/350 nm; 280/340 nm; and 225/300 nm), but one of the humic-like peaks (≈340/415 nm) does not always appear in the EEM fluorescence spectra of the Winter samples. During the cold season, chromophoric compounds are important constituents of rainwater dissolved organic matter and the presence of these highly absorbing and fluorescing compounds may exert a determining effect in atmospheric absorption of solar radiation.  相似文献   

Strike-slip tectonics within the SW Baltic Sea and its relationship to the inversion of the Mid-Polish Trough—evidence from high-resolution seismic data     

Piotr Krzywiec  Regina Kramarska  Piotr Zientara 《Tectonophysics》2003,373(1-4):93

The SW Baltic Sea occupies an area where crustal-scale regional tectonic zones of different age merge and overlap, creating a complex tectonic pattern. This pattern influenced the evolution of the Mesozoic sedimentary basin in this area. We present an interpretation of new high-resolution seismic data from the SW Baltic Sea which provided new information both on modes of the Late Cretaceous inversion of this part of the Danish–Polish Mesozoic basin system as well as on relationship between tectonic processes and syn-tectonic depositional systems. Within the Bornholm–Dar owo Fault Zone, located between the Koszalin Fault and Christiansø Block, both strike-slip and reverse faulting took place during the inversion-related activity. The faulting was related to reactivation of extensional pre-Permian fault system. Syn-tectonic sedimentary features include a prominent, generally S- and SE-directed, progradational depositional system with the major source area provided by uplifted basement blocks, in particular by the Bornholm Block. Sediment progradation was enhanced by downfaulting along a strike-slip fault zone and related expansion of accommodation space. Closer to the Christiansø Block, some syn-tectonic deposition also took place and resulted in subtle thickness changes within the hinge zones of inversion-related growth folds. Lack of significant sediment supply from the inverted and uplifted offshore part of the Mid-Polish Trough suggests that in this area NW–SE-located marginal trough parallel to the inversion axis of the Mid-Polish Trough did not form, and that uplifted Bornholm Block played by far more prominent role for development of syn-inversion depositional successions.  相似文献   

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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Field and geochemical data bearing on the development of a mesozoic volcano-tectonic rift zone and back-arc basin in southernmost South America     

Ronald L. Bruhn  Charles R. Stern  Maarten J. De Wit 《Earth and Planetary Science Letters》1978,41(1):32-46

A broad zone of dominantly subaerial silicic volcanism associated with regional extensional faulting developed in southern South America during the Middle Jurassic, contemporaneously with the initiation of plutonism along the present Pacific continental margin. Stratigraphic variations observed in cross sections through the silicic Jurassic volcanics along the Pacific margin of southernmost South America indicate that this region of the rift zone developed as volcanism continued during faulting, subsidence and marine innundation. A deep, fault-bounded submarine trough formed near the Pacific margin of the southern part of the volcano-tectonic rift zone during the Late Jurassic. Tholeiitic magma intruded within the trough formed the mafic portion of the floor of this down-faulted basin. During the Early Cretaceous this basin separated an active calc-alkaline volcanic arc, founded on a sliver of continental crust, from the then volcanically quiescent South American continent. Geochemical data suggest that the Jurassic silicic volcanics along the Pacific margin of the volcano-tectonic rift zone were derived by crustal anatexis. Mafic lavas and sills which occur within the silicic volcanics have geochemical affinities with both the tholeiitic basalts forming the ophiolitic lenses which are the remnants of the mafic part of the back-arc basin floor, and also the calc-alkaline rocks of the adjacent Patagonian batholith and their flanking lavas which represent the eroded late Mesozoic calc-alkaline volcanic arc. The source of these tholeiitic and calc-alkaline igneous rocks was partially melted upper mantle material. The igneous and tectonic processes responsible for the development of the volcano-tectonic rift zone and the subsequent back-arc basin are attributed to diapirism in the upper mantle beneath southern South America. The tectonic setting and sequence of igneous and tectonic events suggest that diapirism may have been initiated in response to subduction.  相似文献   

Mechanics of low-angle normal faulting: An example from Roosevelt Hot Springs geothermal area, Utah     

Ronald L. Bruhn  Michael R. Yusas  Fernando Huertas 《Tectonophysics》1982,86(4):343-361

Roosevelt Hot Springs geothermal area is located in the Mineral Mountains of southern Utah. The geothermal reservoir is formed by systems of faults and joints in Cenozoic plutonic and Precambrian metamorphic rocks. Low-angle denudation faults, dipping between 5° and 35° to the west, form an important component of the reservoir's structure. These faults developed simultaneously with steeply dipping faults that dissect the low-angle fault plates and merge into denudation faults at depth.Gently westward dipping joints provided planes of weakness along which the denudation faults nucleated. The average coefficient of sliding friction along the faults was less than 0.5 and probably ranged between 0.15 and 0.4. The maximum depth for formation of the denudation faults was estimated as 5 km. Hydrothermally altered cataclasite preserved in the fault zones indicates that faulting occurred under brittle conditions in the presence of chemically reactive fluids. The hydrothermal alteration may have significantly reduced friction in the fault zones.Hydrothermal alteration along fractures in the present geothermal reservoir is similar to that observed in the exhumed denudation faults, indicating that the frictional resistance along faults and joints in the reservoir could be significantly lower than along similar structures in unaltered granitic rock. Studies of the structural stability of the reservoir as a consequence of fluid withdrawal and reinjection should consider possible mechanical effects of this hydrothermal alteration.  相似文献   

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