Seasonal variation of polychlorinated biphenyl concentrations in the southern part of the Baltic Sea   总被引：3，自引：0，他引：3  

Bruhn R  McLachlan MS 《Marine pollution bulletin》2002,44(2):156-163

The impact of seasonal fluctuations in forcing factors such as atmospheric concentration, temperature, and biological productivity on the concentration of polychlorinated biphenyls (PCBs) in the surface water of the southern part of the Baltic Sea was investigated. Water samples were collected on eight cruises over 2 years. A clear seasonal variability in dissolved PCB concentrations was observed with higher levels in summer than in winter and spring. This was attributed to changes in atmospheric concentrations and water temperature, based on measurements showing the PCB levels in the atmosphere and surface water to be close to a partitioning equilibrium. Concentrations in the suspended particulate material (SPM) fraction were also variable, and when the quotient of the organic carbon normalised concentration in SPM and the dissolved concentration was calculated (i.e., the bioaccumulation factor (BAF)), a seasonal pattern was observed which was consistent with kinetic limitations on partitioning into particles caused by plankton growth. However, seasonal variability in the partitioning properties of the SPM may also contribute to this variability.  相似文献   

Adsorption of thorium and protactinium onto different particle types: experimental findings     

Walter Geibert  Regina Usbeck 《Geochimica et cosmochimica acta》2004,68(7):1489-1501

Here we present the results of experiments investigating the adsorption of Protactinium and Thorium onto different particle types in natural seawater. Particle types studied were smectite as a representative of clay, biogenic opal from a cleaned diatom culture, manganese dioxide precipitate, and calcium carbonate. The particles were added to three different types of natural seawater (0.5 mg/L) which were first 0.2 μm-filtered, and the distribution of Pa and Th between dissolved and particulate phase (>0.2 μm) was monitored for 4 to 5 d at increasing time intervals. The tracers applied were the β-emitters ²³³Pa and ²³⁴Th. The measurement technique via β-counting for both nuclides in the same sample is reported here for the first time.The observed recoveries during the experiment range from 40 to 99 (±5) % for Th and from 51 to 105 (±6) % for Pa. The distribution coefficients (K_d) after establishment of an equilibrium cover a wide range for Th from 0.5 to 107 × 10⁶ ml/g, and from 0.03 to 166 × 10⁶ ml/g for Protactinium, depending on particle type and on the type of seawater used.Thorium revealed a specific affinity for all particle types investigated, with varying degree and adsorption kinetics. The results suggest that all particle types investigated may serve as Th carrier phases in the sediment. Pa was found to be less particle reactive than Th in most cases. Th/Pa fractionation factors (F_Th/Pa) were also obtained. Weakest fractionation was found on MnO₂ (F_Th/Pa=1), followed by the chemically cleaned biogenic opal (2.8) and smectite (5.4). The results for calcium carbonate were highly variable. Our experimental results imply that particle composition is indeed playing a role in the differing marine geochemistry of Th and Pa. We conclude that experiments with filtered natural seawater using particle concentrations on a natural level are a helpful approach when investigating the geochemical behaviour of strongly particle-reactive elements like Th and Pa in the marine environment.  相似文献   

An arietitid ammonite from Gower: its palaeogeographical and geomorphological significance     

Regina SmithD.Q. Bowen  John C.W. CopeA. Reid 《Proceedings of the Geologists' Association. Geologists' Association》2002,113(3):217-222

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High-resolution teleseismic tomography of upper-mantle structure using an a priori three-dimensional crustal model   总被引：2，自引：1，他引：2  

Felix Waldhauser  Regina Lippitsch  Edi Kissling  Jörg Ansorge 《Geophysical Journal International》2002,150(2):403-414

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Optical absorption and electron spin resonance in blue and green natural beryl: A reply     

Ana Regina Blak  Sadao Isotani  Shigueo Watanabe 《Physics and Chemistry of Minerals》1983,9(6):279-280

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Fluid-mineral equilibria in a hydrothermal system,Roosevelt hot springs,Utah     

Regina M. Capuano  David R. Cole 《Geochimica et cosmochimica acta》1982,46(8):1353-1364

The availability of fluids and drill cuttings from the active hydrothermal system at Roosevelt Hot Springs allows a quantitative comparison between the observed and predicted alteration mineralogy, calculated from fluid-mineral equilibria relationships. Comparison of all wells and springs in the thermal area indicates a common reservoir source, and geothermometer calculations predict its temperature to be higher ($\text{288°C ± 10°}$) than the maximum measured temperature of 268°C.The composition of the deep reservoir fluid was estimated from surface well samples, allowing for steam loss, gas release, mineral precipitation and ground-water mixing in the well bore. This deep fluid is sodium chloride in character, with approximately 9700 ppm dissolved solids, a pH of 6.0, and gas partial pressures of O₂ ranging from 10^?32 to 10^?35 atm, CO₂ of 11 atm, H₂S of 0.020 atm and CH₄ of 0.001 atm.Comparison of the alteration mineralogy from producing and nonproducing wells allowed delineation of an alteration pattern characteristic of the reservoir rock. Theoretical alteration mineral assemblages in equilibrium with the deep reservoir fluid, between 150° and 300°C, in the system Na₂O-K₂O-CaO-MgO-FeO-Fe₂O₃-Al₂O₃-H₄SiO₄-H₂O-H₂S-CO₂-HCl, were calculated. Minerals theoretically in equilibrium with the calculated reservoir fluid at $\text{>240°C}$ include sericite, K-feldspar, quartz, chalcedony, hematite, magnetite and pyrite. This assemblage corresponds with observed higher-temperature ($\text{>210°C}$) alteration assemblage in the deeper parts of the producing wells. The presence of montmorillonite and mixed-layer clays with the above assemblage observed at temperatures <210°C corresponds with minerals predicted to be in equilibrium with the fluid below 240°C.Alteration minerals present in the reservoir rock that do not exhibit equilibrium with respect to the reservoir fluid include epidote, anhydrite, calcite and chlorite. These may be products of an earlier hydrothermal event, or processes such as boiling and mixing, or a result of errors in the equilibrium calculations as a result of inadequate thermochemical data.  相似文献   

Chemical Characterisation of NIST Silicate Glass Certified Reference Material SRM 610 by ICP-MS, TIMS, LIMS, SSMS, INAA, AAS and PIXE   总被引：2，自引：0，他引：2  

Alexander B.E. Rocholl  Klaus Simon  Klaus Peter Jochum  Frank Bruhn  Roland Gehann  Utz Kramar  Werner Luecke  Michael Molzahn  Ernst Pernicka  Michael Seufert  Bernhard Spettel  Jens Stummeier 《Geostandards and Geoanalytical Research》1997,21(1):101-114

National Institute of Science and Technology (NIST) silicate glass SRM 610 is widely used as a certified reference material for various micro-analytical techniques such as SIMS or laser ablation ICP-MS. SRM 610 has been nominally doped with sixty one trace elements at the 500 μg g⁻¹ level, but certified concentration data exist for only a few of these elements. This study reports concentration data for fifty nine trace elements obtained by ICP-MS, SSMS, LIMS, TIMS, INAA, AAS, and PIXE analyses of two different SRM 610 wafers. Most elements fall within a 10% band around a median value of about 440 μg g⁻¹. The REE concentrations are shown to be constant to 3% (1 σ), thus emphasizing the value of SRM 610 as a reference material for REE analyses.
Comparison of our values with published data suggests that different SRM 610 wafers are, within errors, chemically identical for most elements. Exceptions to this general rule appear to be restricted to elements which were partly lost during the production of the glass, e.g. Ag and Br. On the basis of six independent determinations of Rb concentrations, which are systematically lower by a few percent than the reported NIST value, we argue that the certified Rb concentration may not be representative for all distributed SRM 610 wafers.  相似文献   

Geophysical Characterization of Smelting Wastes: A Case History     

Karl J. Ellefsen  Regina M. Bochicchio 《Ground Water Monitoring & Remediation》1995,15(2):169-176

The thicknesses of slag piles at a smelling site in Midvale. Utah, were determined using geophysical methods; this information was needed to estimate the cost of removing or isolating slag that has the potential to contaminate ground water. From a small-scale preliminary investigation that, included terrain-conductivity profiling, low-frequency resistivity measurements, and induction logging, the electrical resistivities of the slag and the underlying sediment were determined to be approximately 100 Ω-m and 15 Ω-m, respectively. Because electromagnetic measurements are affected by such significant contrasts, terrain-conductivity profiling and time-domain electromagnetic soundings were used to determine the thicknesses of the slag piles. Generally, the estimated thicknesses from both methods were consistent and geologically plausible. In some instances, reliable estimates of the thicknesses could not be obtained because, for example, the measurements were affected by buried metal objects.
In this case study, we emphasize three principles that might help investigators at other smelter sites. First, a small-scale preliminary investigation saves time and money because those geophysical methods that have the greatest likelihood of success can be determined. Second, when the results from several geophysical methods are consistent, the confidence in the interpretation increases. Third, geophysical characterization is not always successful. Nonetheless, because of its outstanding advantages, it should be used before other more expensive characterization methods arc tried.  相似文献   

Relations between climatic–geomorphological parameters and sediment yield in a mediterranean semi-arid area (Sicily,southern Italy)     

Sergio Grauso  Andrea Pagano  Grazia Fattoruso  Piero De Bonis  Filippo Onori  Pasquale Regina  Carlo Tebano 《Environmental Geology》2008,54(2):219-234

In the present work on-going research is discussed whose primary goal is to test some statistical methods to estimate the average yearly area-specific sediment yield (SSY). Using geomorphological and climatic parameters various multiple regression formulae have been set up based on SSY observed data from 16 catchments of Sicily. Three distinct techniques were adopted to select the parameters to be used in the equations: simple correlation, stepwise regression analysis and a supervised geomorphological–statistical correlation. The comparison of the results showed the effectiveness of the stepwise analysis, which led to a regression equation with a coefficient of determination (r ²) of 0.87. Nevertheless, even this methodology showed some elements of uncertainty that have caused, in some cases, appreciable differences between observed and predicted values (mean percentage error equal to 26%). These differences are likely either due to the hydraulic regime of most of Sicilian watercourses (typical of semi-arid regions) or to hidden factors (e.g., topography, human impact and concentrated erosion), which can greatly affect the processes of sediment production and transport. The study has pointed out the need to take into account a larger number of observations and to perform the analysis of relations between suitable variables and SSY at a more detailed time resolution.  相似文献   

Soil-erosion assessment at basin scale through 137Cs content analysis based on pedo-morphological units     

S. Grauso  F. Onori  M. Esposito  M. Neri  G. Armiento  P. Bartolomei  C. Crovato  F. Felici  M. Marcinnò  P. Regina  C. Tebano 《Environmental Geology》2008,54(2):235-247

Soil loss evaluation by means of radioisotopic content measurements represents a promising technique, half-way between field surveys and theoretical models, which still suffers from its practical limits when applied at basin scale. A main limit is represented by the costs of field investigations and laboratory investigations on the high number of soil samples required by a traditional sampling scheme, such as regular grid or transects. A non-conventional soil sampling scheme was tested with the aim to consider a relative scanty number of soil samples and to verify the feasibility of this technique on large areas. This scheme was based on the hypothesis that land analysis and classification could point out areas characterised by homogeneous behaviour with respect to the ¹³⁷Cs deposition and transmission model. A Geographic Information System (GIS)-aided procedure allowed to classify the selected basin area in pedo-morphological units, representative of the different pedologic, morphologic and land-use conditions, to locate few sampling points for each unit. Outcomes pointed out a low correlation between ¹³⁷Cs contents and soil physical and compositional characteristics. Nevertheless, the isotopic methodology allowed to estimate a total soil loss value at basin scale almost consistent with both observed data, given by reservoir sedimentation measurements and estimates from the application of the RUSLE model. Thus, the results can be considered encouraging and they allow to deem that the isotopic methodology can be refined in order to account for erosion and deposition processes even at river basin scale and with a limited number of soil samples.  相似文献