European VOC Emission Estimates Evaluated by Measurements and Model Calculations     

øystein Hov  Asgeir Sorteberg  Norbert Schmidbauer  Sverre Solberg  Frode Stordal  David Simpson  Anne Lindskog  Hans Areskoug  Pedro Oyola  Heikki Lättilä  Niels Z. Heidam 《Journal of Atmospheric Chemistry》1997,28(1-3):173-193

Observations and model calculations of the concentration of hydrocarbonsat five Scandinavian rural sites during March–June 1993are reported.Decreasing concentrations from March to June are observedat all sites. The highest concentrations of hydrocarbons were found in air massescoming in from the southwest to southeast, indicating that long rangetransport fromcontinental Europe and the U.K. is important in pollution episodes. An episode of elevated concentrations of hydrocarbons observed at three of the sites in the middle of Marchis described and discussed in relation to the synoptic situation and thepresenceof other chemical compounds (NO₂, PAN, total nitrate andozone).A Lagrangian numerical model is used to calculate the concentrations of theindividual hydrocarbons at the fivesites and comparison with observations is made.The calculated concentrations for nonmethane hydrocarbons with quite longchemicallifetimes agree well with the observations.For the sum of observed and calculated hydrocarbons the correlationcoefficientsare in the range of 0.65–0.88 for the five sitesand the ratio between calculated and measured concentrations was0.72–0.97, indicating thatthe European VOC emission inventory is quite well estimated.  相似文献   

Carboxylic Acids: Seasonal Variation and Relation to Chemical and Meteorological Parameters   总被引：1，自引：0，他引：1  

K. Granby  A. H. Egeløv  T. Nielsen  C. Lohse 《Journal of Atmospheric Chemistry》1997,28(1-3):195-207

Formic and acetic acid measured as daily averages in 1993–1994show equal and highly correlated concentrations up to 3 ppb in the summer(May–August). In the winter (October–March) the formicacid/acetic acid ratio was 0.6 and the formic acid concentrations wereusually below 1 ppb. In winter the carboxylic acids correlate withO_x, NO_y, SO₂ and particulatesulphur. The main sources are suggested to be ozonolysis of anthropogenicalkenes and reactions between peroxyacetyl radicals and RO₂radicals. In spring–summer the carboxylic acids correlate withO₃, O_x, HNO₃, PAN,NO_y, SO₂, particulate sulphur and temperature.In addition to the sources of the winter a contribution from ozonolysis ofbiogenic alkenes is likely. Quite similar formic acid/acetic acid ratios forall wind directions suggest that the source(s) are atmospheric oxidationprocesses distributed over large areas. The highest concentrations occurringfor winds from east to south and the correlation with e.g., particulatesulphur indicate chemical production in polluted air masses during longrange transport.  相似文献   

Environmental isotopes (18O, 2H, and 87Sr/86Sr) as a tool in groundwater investigations in the Keta Basin, Ghana     

Niels O. Jørgensen  Bruce K. Banoeng-Yakubo 《Hydrogeology Journal》2001,9(2):190-201

Analyses of environmental isotopes (¹⁸O, ²H, and ⁸⁷Sr/⁸⁶Sr) are applied to groundwater studies with emphasis on saline groundwater in aquifers in the Keta Basin, Ghana. The ⁸⁷Sr/⁸⁶Sr ratios of groundwater and surface water of the Keta Basin primarily reflect the geology and the mineralogical composition of the formations in the catchments and recharge areas. The isotopic compositions of ¹⁸O and ²H of deep groundwater have small variations and plot close to the global meteoric water line. Shallow groundwater and surface water have considerably larger variations in isotopic compositions, which reflect evaporation and preservation of seasonal fluctuations. A significant excess of chloride in shallow groundwater in comparison to the calculated evaporation loss is the result of a combination of evaporation and marine sources. Groundwaters from deep wells and dug wells in near-coastal aquifers are characterized by relatively high chloride contents, and the significance of marine influence is evidenced by well-defined mixing lines for strontium isotopes, and hydrogen and oxygen stable isotopes, with isotopic compositions of seawater as one end member. The results derived from environmental isotopes in this study demonstrate that a multi-isotope approach is a useful tool to identify the origin and sources of saline groundwater. Electronic Publication  相似文献   

Analytical transmission electron microscopy of oscillatory zoned grandite garnets     

Kilian Pollok  Bjørn Jamtveit  Andrew Putnis 《Contributions to Mineralogy and Petrology》2001,141(3):358-366

Oscillatory zoned grandite garnets from skarns of the Oslo rift region (southern Norway) have been studied using analytical transmission electron microscopy (ATEM). Our results show lamellae with a width varying from about 10 nm to more than 500 nm in both periodic and non-periodic sequences, which represent oscillatory zoning at a very fine scale. The compositions of adjacent lamellae alternate bimodally from X_and=0.55-0.75 to X_and=0.95-1.0. High resolution (HRTEM) images show that the compositional interfaces are sharp and coherent. Oscillatory zoning at the nm-scale puts constrains on the origin of oscillatory zoning in grandites and underlines the dynamic nature of the crystal growth process. The influence of growth rate is discussed against the background of local growth dynamics and external forcing at different length scales. This study emphasises the importance of adequate spatial resolution in analysing chemical variations in grandite garnets and shows that commonly applied methods (e.g. optical microscopy, backscattered electron imaging and electron or ion microprobe) are not sufficient to detect 'real' zonation patterns. Finally, proposed hypotheses on the origin of birefringence of grandite garnets with intermediate compositions are reviewed and discussed on the basis of the observed microstructure.  相似文献   

Precession‐induced flows in liquid‐filled containers and in the Earth's core     

M. A. Pais  J. L. Le Mouël 《Geophysical Journal International》2001,144(3):539-554

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Evolution of the skærgaard magma: evidence from crystallized melt inclusions     

Karen Hanghøj  Minik T. Rosing  C. Kent Brooks 《Contributions to Mineralogy and Petrology》1995,120(3-4):265-269

Polymineralic aggregates composed of clinopyroxene, Fe-Ti oxide minerals, apatite and accessory K-feldspar, biotite, and amphibole are enclosed in cumulus plagioclase grains in the Middle Zone of the Skærgaard intrusion. The chemistry of the minerals in the aggregates, and the textural relations between the aggregates and the host plagioclase grains indicate that they represent inclusions of the contemporaneous melt of the Skærgaard intrusion. Through mass balance calculations a quantitative estimate of the melt composition for this level in the intrusion can be obtained, and this estimate confirms that the silica content in the Middle Zone melt was similar to, or possibly even lower than, the silica content in the initial Skærgaard melt, and relatively enriched in iron.  相似文献   

Recent crustal movements and earthquakes in the area of the Tornquist Zone     

Søren Gregersen 《Studia Geophysica et Geodaetica》1995,39(3):257-261

Summary The present state of knowledge on recent crustal movements, stresses and earthquakes around the Tornquist Zone has been collected. It is found that the Tornquist Zone is neither geodetically nor seismically active, but it separates regions of different earthquake activity.Members of the working group on recent crustal movements around the Tornquist Zone: H. Lykke Andersen, M.C. Oncescu, V. Mocanu, E. and P. Bankwitz, G. Grünthal, and S. Gregersen.  相似文献   

Subsurface temperature measurements and terrestrial heat flow estimates in the Aswan region,Egypt     

J. Šafanda  M. Krešl  V. Čermák  A. R. G. Hasanean  H. A. Deebes  M. A. Abd-Alla  S. M. Moustafa 《Studia Geophysica et Geodaetica》1995,39(2):162-176

Summary The results of temperature measurements in six boreholes, drilled near the west shores of the Lake Nasser in the Aswan region in the Nubian Desert, are reported. Temperature-depth profiles, complemented by thermal conductivity determinations of surface rock samples, were used to calculate the existing range of heat flow density in the region as 40 ÷ 60 mWm⁻², which is consistent with the values from the adjacent areas, reported in the literature. The extrapolated mean annual ground surface temperatures amount, on the average, to 30°C, which is 3 K higher than the mean annual air temperature in the region.  相似文献   

Stress field in the earth's crust with curved boundaries     

Jiří Trešl  Jiří Mičke 《Studia Geophysica et Geodaetica》1993,37(2):125-140

Summary A two-dimensional theory of gravitational stresses in the Earth's crust with curved boundaries is presented. The crust is modelled by an elastic plate lying on an elastic half-space. The solution obtained in the case of periodically varying boundaries is shown to be very sensitive to the ratio of both elastic parameters. Moreover, the geometrical configuration of both boundaries and their phase shift are of great importance for the resulting stress pattern.  相似文献   

Sensitivity study and validation of a land surface parameterization using the HAPEX-MOBILHY data set   总被引：6，自引：0，他引：6  

Bruno Jacquemin  Joël Noilhan 《Boundary-Layer Meteorology》1990,52(1-2):93-134

A simple parameterization of land surface processes, amenable to the structure of a two-layer soil model, including a representation of the vegetation, has been designed for use in meteorological models. Prior to implementation in a mesoscale model, it is necessary to check the components and to verify the good working order of the parameterization as a whole. The aims of this paper then are: (i) evaluation and a sensitivity study of the various components of the model, specifying the needed accuracy for the parameters; (ii) micrometeorological validation of the model against the HAPEX-MOBILHY data set.First, we present the basic scheme. The focus is on the parameterization of surface resistance, and especially on its relationship with soil moisture.A sensitivity study is then performed through a set of one-dimensional simulations which allow a full interaction between the ground and the atmosphere. Above bare ground, it is shown that both soil texture and initial moisture greatly influence the outcome of the simulation. Latent heat flux ranges from that associated with potential evaporation through a switch-like behavior to that of dry soil. Next, the effects of transpiring vegetation canopies on the physical processes involved and the surface energy balance are examined. The sensitivity of the latent heat flux to changes in the soil and canopy parameters is emphazised; the major influence of the initial mean soil moisture and of the vegetation cover is pointed out. Finally, the evolution of the boundary layer in response to various surface conditions is studied.A validation of the land surface scheme is conducted through daily cycles during cloudless days. Simulated turbulent fluxes are successfully compared to micrometeorological measurements over a maize field at different growth stages. Over a pine forest, the correct simulation of the turbulent fluxes is obtained with an adequate parameterization of the surface resistance accounting for the atmospheric moisture deficit.  相似文献