Ground Based FTIR Measurements of Stratospheric Species from Harestua, Norway During Sesame and Comparison with Models     

B. Galle  J. Mellqvist  D.W. Arlander  I. Fløisand  M.P. Chipperfield  A.M. Lee 《Journal of Atmospheric Chemistry》1999,32(1):147-164

Vertical columns of HF, HCl, HNO3, ClONO2, N2O, ClO and COF2 were measured at Harestua, Norway (60.22° N, 10.75° E, Elevation 600 a.s.l.) beginning on 24 November 1994 and concluding on 1 May 1995 during Phase-III of the SESAME (Second European Stratospheric Arctic and Mid-latitude Experiment) measurement campaign. The vertical columns of HCl, HNO3 and ClONO2 measured on 81 days were compared with columns calculated by the 3-D Cambridge model SLIMCAT. In addition the results were also interpreted by comparison with a photochemical trajectory model. Good agreement was seen for HCl while the nitrogen compounds showed larger discrepancies, especially for ClONO2. Evidence for chlorine activation was seen with 65% reduction of the chlorine reservoirs (HCl + ClONO2) while the levels of ClO were greatly enhanced. Interpretation of the loss with the trajectory model indicated condensation of chlorine on PSCs. The vertical column ratio of COF2 and HF was measured to 0.21 outside the vortex and a factor of two lower inside. The recovery of ClONO2 was seen to be much faster than that of HCl in the early spring.  相似文献   

Progress in the Study of Climatic Extremes in Northern and Central Europe   总被引：1，自引：0，他引：1  

R. Heino  R. Brázdil  E. Førland  H. Tuomenvirta  H. Alexandersson  M. Beniston  C. Pfister  M. Rebetez  G. Rosenhagen  S. Rösner  J. Wibig 《Climatic change》1999,42(1):151-181

A study of the long-term changes of various climatic extremes was made jointly by a number of European countries. It was found that the changes in maximum and minimum temperatures follow, in broad terms, the corresponding well-documented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have increased. As a result, the study confirms that the diurnal temperature range has mostly decreased during the present century in Northern and Central Europe. Frost has become less frequent. Two extreme-related precipitation characteristics, the annual maximum daily precipitation and the number of days with precipitation 10 mm, show no major trends or changes in their interannual variability. An analysis of return periods indicated that in the Nordic countries there were high frequencies of extraordinary 1-day rainfalls both in the 1930s and since the 1980s. There have been no long-term changes in the number of high wind speeds in the German Bight. Occurrences of thunderstorms and hails show a decreasing tendency in the Czech Republic during the last 50 years. Finally, using proxy data sources, a 500-year temperature and precipitation event graph for the Swiss Mittelland is presented. It shows large interdecadal variations as well as the exceptionality of the latest decade 1986-1995.  相似文献   

The distribution of trace metals in the western North Atlantic off Nova Scotia     

J.M. Bewers  Bjørn Sundby  P.A. Yeats 《Geochimica et cosmochimica acta》1976,40(6):687-696

The distributions of Fe, Mn, Zn, Cu, Ni, Cd and Co have been determined in a section across the Scotian Shelf into the Atlantic Slope water. Significant differences in concentration exist for most of the trace metals between the four water masses in the section. Depletions of trace metal concentration in the highly productive Atlantic Slope water relative to the underlying Central Atlantic water are thought to be due to biological activity.The distributions of Fe and Mn are strongly related to the distribution of suspended particulate matter. The concentrations of Fe and Mn, extracted from the suspended matter on the Scotian Shelf, are considerably higher than those in the non-detrital fraction of the underlying sediments. This suggests that post-depositional changes cause the loss of both elements from the non-detrital fraction of the particles. Whereas Mn shows major nearshore increases in concentration related to continental runoff, nearshore Fe concentrations are largely controlled by particulate matter distribution. Continental runoff does not appear to have much influence upon the distributions of the other trace metals.  相似文献   

Solved and unsolved problems in the chrysophyceae     

Jørgen Kristiansen 《Aquatic Sciences - Research Across Boundaries》1981,43(1):4-4

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Trace element partitioning and melt structure: An experimental study at 1 atm pressure     

Bjørn O. Mysen  David Virgo 《Geochimica et cosmochimica acta》1980,44(12):1917-1930

Diopside-melt and forsterite-melt rare earth (REE) and Ni partition coefficients have been determined as a function of bulk compositions of the melt. Available Raman spectroscopic data have been used to determine the structures of the melts coexisting with diopside and forsterite. The compositional dependence of the partition coefficients is then related to the structural changes of the melt.The melts in all experiments have a ratio of nonbridging oxygens to tetrahedral cations ($\text{NBO}\text{T}$) between 1 and 0. The quenched melts consist of structural units that have, on the average, 2 (chain), 1 (sheet) and 0 (three-dimensional network) nonbridging oxygens per tetrahedral cation. The proportions of these structural units in the melts, as well as the overall $\text{NBO}\text{T}$, change as a function of the bulk composition of the melt.It has been found that Ce, Sm, Tm and Ni crystal-liquid partition coefficients ($\text{K}{}^{\mathrm{crystal?liq}}{}_{\mathrm{i}}\text{=}\text{C}{}^{\mathrm{crystal}}{}_{\mathrm{i}}\text{C}{}^{\mathrm{liq}}{}_{\mathrm{i}}$) decrease linearly with increasing $\text{NBO}\text{T}$. The values of the individual REE crystal-liquid trace element partition coefficients have different functional relations to $\text{NBO}\text{T}$, so that the degree of light REE enrichment of the melts would depend on their $\text{NBO}\text{T}$.The solution mechanisms of minor oxides such as CO₂, H₂O, TiO₂, P₂O₅ and Fe₂O₃ in silicate melts are known. These data have been recast as changes of $\text{NBO}\text{T}$ of the melts with regard to the type of oxide and its concentration in the melt. From such data the dependence of crystal-liquid partition coefficients on concentration and type of minor oxide in melt solution has been calculated.  相似文献   

Fenitization of layered mafic rocks in the Lillebukt alkaline complex,Stjernoy, Norway     

K. Kjøsnes 《Lithos》1980,13(2):215

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Titan-aegirine from early Tertiary ash layers in northern Denmark     

J.G Rønsbo  A.K Pedersen  J Engell 《Lithos》1977,10(3):193-204

Microprobe analyses on a xenocrystic suite of salites, aegirine-augites, aegirines, titan-aegirines and acmites from a lower Tertiary ash layer in northern Denmark are presented. The sodic pyroxenes show an unusual titan-enrichment and up to 42 mol.% of the component $\text{NaTi}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{4+}}\text{M}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{2+}}\text{Si}{}_3\text{O}{}_6\text{(}\text{M = Fe}{}^{\mathrm{2+}}\text{,}\text{Mn or Mg}\text{)}$, is estimated. Optical absorption measurements show no evidence for Ti³⁺. The titan-aegirines were formed during late to post-magmatic crystallization in a system with a high Ti⁴⁺/Fe²⁺ ratio and were followed by acmite showing enrichment in jadeite. Comparison with experimentally investigated titan-aegirine indicates crystallization far below the Mn₂O₃Mn₃O₄f₀₂ buffer.  相似文献   

Water color and its relation to primary production     

N. K. Højerslev 《Boundary-Layer Meteorology》1980,18(2):203-220

It is shown both experimentally and theoretically that the depth of the euphotic zone is related to the color of the sea defined as a color index equal to the ratio of the upwelling blue (450 nm) and green (525 nm) nadir daylight just below the sea surface. The relationship is valid for most sea waters where the albedo from the bottom is negligible near the sea surface and where the composition of suspended and dissolved matter is not largely determined either by water drainage from land or by turbidity currents. The standing stock of phytoplankton and its primary productivity within the euphotic zone can approximately be given in terms of the color of the sea. The accuracy in determining each of the above two biological quantities from color measurements at the sea surface is not satisfactory at present. This holds particularly true when the color of the sea is measured remotely by present satellite techniques.  相似文献   

Geochemical aspects of permeability controlled partial melting and fractional crystallization     

Sven Maaløe 《Geochimica et cosmochimica acta》1982,46(1):43-57

Magma accumulation in the mantle requires that the mantle be permeable. Experimental investigations show that the permeability threshold first will be attained after a certain degree of partial melting. The influence of the permeability threshold on the composition of partial melts is evaluated using the fayalite-forsterite system as an example. In addition the variation in trace element concentrations are calculated for different distribution coefficients. Primary magmas formed by accumulation when a minimal degree of partial melting is required for permeability display a remarkably small variation in composition up to 30% partial melting. It is suggested from REE abundances that primary tholeiitic magmas have been generated by permeability controlled partial melting. The compositions of the primary magmas generated by permeability controlled partial melting will not differ much from the compositions obtained by batch melting, but the degrees of partial melting will differ for similar compositions.  相似文献   

Effect of an oil spill in Spitzbergen in 1978     

Bjørn Gulliksen  Jens Petter Taasen 《Marine pollution bulletin》1982,13(3):96-98

The oil content in the sediment and the marine life along the arctic shores of Van Mijenfjord, Spitzbergen, were investigated about two years after a spill from diesel storage tanks. High values of oil were recorded in the sediment along the shore near the tanks. The shore fauna is generally poor in these areas and the only biological effect detected was the disappearance of the amphipod Gammarus setosus from the surface layers.  相似文献