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In the present phase of the volcanic activity on Nea Kameni / Santorini / Greece the calc-alkalic volcanic rocks are decomposed by H2O, CO2 and SO2 gases of about 100 °C. Using a method ofGresens (1967) for the determination of gains and losses of compounds five different processes could be distinguished:
  1. leaching of compounds
  2. enrichment of Ca as gypsum
  3. increase of Fe2O3 (6%–11%), TiO2 (0,8%–3%) and Zr
  4. enrichment of Al2O3 (15%–29%), TiO2 (0,8%–1,5%) and K
  5. increase of Al2O3 (15%–26%), Fe2O3 (6%–9%), TiO2 (0,8%–1,3%), Sr, Ba, Pb and Zr
Finally a model for the process of decomposition of calc-alkalic volcanic rocks by sulfuric acid was developed.  相似文献   
2.
On June 20, 1971, an instrumented probe designated PAET entered the atmosphere near Bermuda at a velocity of 6.6 km/sec carrying experiments designed for use at planets other than the Earth. Instruments to measure in situ the structure and composition of the atmosphere included accelerometers, pressure and temperature sensors, a mass spectrometer, and a radiometer (to sense characteristic emission from the probe shock layer at high speeds).The experiments were largely successful. The thermal structure of the atmosphere, including two major reversals in gradient, was shown to be well defined to an altitude of 80 km by comparison with more conventional meteorological soundings. The atmospheric mean molecular weight was defined within a percent by the structure experiment. The radiometers defined the bulk composition accurately and the trace quantity of CO2 to one significant figure. The mass spectrometer functioned properly, but failed to give the correct composition because of problems in its sampling system. Oxygen was depleted, apparently by chemical reactions before reaching the spectrometer, and the inlet leak conductance was reduced from its preflight value by an order of magnitude. There is reason to believe that contamination by large molecules from the heat shield was responsible. This experiment should stimulate intensive laboratory work on sampling systems, so that similar problems do not arise in measurements of atmospheric composition at the planets.Results of auxiliary experiments to measure atmospheric water vapor, vehicle dynamics and heating, and communications blackout are also given.  相似文献   
3.
Details on the preparation of a Laterite Standard Reference Material (SRM) from Venezuela, on the homogeneity-testing and the round-robin testing scheme from 11 international laboratories are given. The proposed values (%) for the concentrations of the main constituents are: Al2O3: 37.38, SiO2: 1.16, TiO2: 3.15, Fe2O3: 35.77 and LOI, 22.44. The following statistical parameters are also reported: the arithmetic mean, the variance, the standard deviation, the coefficient of variation, the median, the skewness factor, the preferred mean, the geometric mean, the Gastwirth Median and the dominant cluster mode.  相似文献   
4.
In 1997, the COmet Nucleus TOUR (CONTOUR) was selected byNASA for a new start as part of the Discovery line. In this paper, we review the status of the mission, the mission timeline and the instruments to be flown. Detail is given of the science goals and how they are to be accomplished.  相似文献   
5.
The in situ measurements of the Galileo Probe Mass Spectrometer (GPMS) were expected to constrain the abundances of the cloud-forming condensible volatile gases: H2O, H2S, and NH3. However, since the probe entry site (PES) was an unusually dry meteorological system—a 5-μm hotspot—the measured condensible volatile abundances did not follow the canonical condensation-limited vertical profiles of equilibrium cloud condensation models (ECCMs) such as Weidenschilling and Lewis (1973, Icarus 20, 465-476). Instead, the mixing ratios of H2S and NH3 increased with depth, finally reaching well-mixed equilibration levels at pressures far greater than the lifting condensation levels, whereas the mixing ratio of H2O in the deep well-mixed atmosphere could not be measured. The deep NH3 mixing ratio (with respect to H2) of (6.64±2.54)×10−4 from 8.9-11.7 bar GPMS data is consistent with the NH3 profile from probe-to-orbiter signal attenuation (Folkner et al., 1998, J. Geophys. Res. 103, 22847-22856), which had an equilibration level of about 8 bar. The GPMS deep atmosphere H2S mixing ratio of (8.9±2.1)×10−5 is the only measurement of Jupiter's sulfur abundance, with a PES equilibration level somewhere between 12 and 15.5 bar. The deepest water mixing ratio measurement is (4.9±1.6)×10−4 (corresponding to only about 30% of the solar abundance) at 17.6-20.9 bar, a value that is probably much smaller than Jupiter's bulk water abundance. The 15N/14N ratio in jovian NH3 was measured at (2.3±0.3)×10−3 and may provide the best estimate of the protosolar nitrogen isotopic ratio. The GPMS methane mixing ratio is (2.37±0.57)×10−3; although methane does not condense on Jupiter, we include its updated analysis in this report because like the condensible volatiles, it was presumably brought to Jupiter in icy planetesimals. Our detailed discussion of calibration and error analysis supplements previously reported GPMS measurements of condensible volatile mixing ratios (Niemann et al., 1998, J. Geophys. Res. 103, 22831-22846; Atreya et al., 1999, Planet. Space Sci. 47, 1243-1262; Atreya et al., 2003, Planet. Space Sci. 51, 105-112) and the nitrogen isotopic ratio (Owen et al., 2001b, Astrophys. J. Lett. 553, L77-L79). The approximately three times solar abundance of NH3 (along with CH4 and H2S) is consistent with enrichment of Jupiter's atmosphere by icy planetesimals formed at temperatures <40 K (Owen et al., 1999, Nature 402 (6759), 269-270), but would imply that H2O should be at least 3×solar as well. An alternate model, using clathrate hydrates to deliver the nitrogen component to Jupiter, predicts O/H?9×solar (Gautier et al., 2001, Astrophys. J. 550 (2), L227-L230). Finally we show that the measured condensible volatile vertical profiles in the PES are consistent with column-stretching or entraining downdraft scenarios only if the basic state (the pre-stretched column or the entrainment source region) is described by condensible volatile vertical profiles that are drier than those in the equilibrium cloud condensation models. This dryness is supported by numerous remote sensing results but seems to disagree with observations of widespread clouds on Jupiter at pressure levels predicted by equilibrium cloud condensation models for ammonia and H2S.  相似文献   
6.
The quantitative determination of the main compounds Al (OH)3 (gibbsite) as Al2O3 and hydrated Fe-oxides as Fe2O3 in natural and beneficiated ferruginous bauxites (low-grade bauxites) by X-ray diffraction (XRD) is presented employing the external standard method. The calibration parameters for the analysis by XRD were ascertained by using ten synthetic mixtures of the pure oxides Al2O3 and Fe2O3 which were calcined at 1200°C. The concentration ranges for Fe2O3 were 10–70 wt.% and those for alumina 30–90 wt.%. The standard deviation for the calibrations of the two oxides was 3.33 wt.%. The results obtained by XRD for both oxides were compared with those attained by X-ray fluorescence. The precision of the determinations by XRD was ascertained by analysing a natural sample consecutively 5 times. The accuracy was verified by the analysis of two international standard reference materials with low silica contents.  相似文献   
7.
Abstract— A simple thermal model is developed to determine the temperature history of the inlet tube of the Huygens probe gas chromatograph mass spectrometer (GCMS) after its fortuitous emplacement on the surface of Saturn's moon Titan. The model parameters are adjusted to match the recorded temperature history of a nearby heater, taking into account heat losses by conduction to the rest of the probe and to Titan's cold atmosphere. The model suggests that after impact when forced convective cooling ceased, the inlet temperature rose from ?110 K to an asymptotic value of only ?145 K. This requires that the inlet was embedded in a surface that acted as an effective heat sink, most plausibly interpreted as wet or damp with liquid methane. The data appear inconsistent with a tar or dry, fine‐grained surface, and the inlet was not warm enough to devolatilize methane hydrate.  相似文献   
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