高程校正在自然电场法中的应用

自然电场法梯度测量是一种原理看似简单,但实际操作却较为困难的地球物理方法。自然电场法对物理性质差异较大的物体有着敏感的反应。自然电场曲线所包含的信息即包括了地下异常信息,同时又包括地形高程等影响信息。实践证明,对于高程变化较大的地区,自然电场曲线经过地形高程等校正之后,才能更为准确的反应地下异常信息。     

地球扁率在其历史上的变化

地球的形状变化是地球演化研究的基本问题之一.为了确定地球形状的变化需要了解各个地质历史时期其扁率的变化.根据地球的扁率公式,得到扁率与地球的半径、质量和角速度关系.通过推测地球的半径、质量和角速度的变化量,计算出地球各个时期的扁率.地球的扁率自形成以来总体趋势在减小.地球是个固液混合的椭球体,在各个地质历史时期中地球扁率的真实值应该小于计算的扁率值.     

内蒙古羊蹄子山-磨石山钛矿床的物性特征及有效找矿方法探讨

内蒙古羊蹄子山-磨石山钛矿床是近几年国内所发现的新型钛矿床,其中,羊蹄子山矿带为热液改造型富钛矿床,磨石山矿带为沉积变质型富钛矿床。这2个矿带的主要有用矿物为锐钛矿、金红石及钛铁矿。根据大量物性测量和研究对比,发现富钛矿石具有较高的密度、弱磁性、高极化率、较低电阻率的物性特征。通过重、磁探测发现了多处有意义的异常,对部分异常进行了钻探验证,结果表明,高精度重力测量是有效的找矿方法,高精度磁法为基本的找矿方法。文章结合该区岩(矿)石的物性特征,探讨了大功率激电和频率域电磁法寻找此类矿床的有效性和可行性。并据此指出,重力与磁法面积测量相结合,在重点地段进行激电与电磁测深,是寻找同类矿床的有效的物探技术方法组合。     

Contaminants in molting long-tailed ducks and nesting common eiders in the Beaufort Sea

In 2000, we collected blood from long-tailed ducks (Clangula hyemalis) and blood and eggs from common eiders (Somateria mollissima) at near-shore islands in the vicinity of Prudhoe Bay, Alaska, and at a reference area east of Prudhoe Bay. Blood was analyzed for trace elements and egg contents were analyzed for trace elements, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Except for Se (mean=36.1 microg/g dry weight (dw) in common eiders and 48.8 microg/g dw in long-tailed ducks), concentrations of trace elements in blood were low and, although several trace elements differed between areas, they were not consistently higher at one location. In long-tailed ducks, Se in blood was positively correlated with activities of two serum enzymes, suggestive of an adverse effect of increasing Se levels on the liver. Although common eiders had high Se concentrations in their blood, Se residues in eggs were low (mean=2.28 microg/g dw). Strontium and Ni were higher in eggs near Prudhoe Bay than at the reference area, but none of the other trace elements or organic contaminants in eggs differed between locations. Concentrations of Ca, Sr, Mg, and Ni differed among eggs having no visible development, early-stage embryos, or late-stage embryos. Residues of 4,4'-DDE, cis-nonachlor, dieldrin, hexachlorobenzene, oxychlordane, and trans-nonachlor were found in 100% of the common eider eggs, but at low concentrations (means of 2.35-7.45 microg/kg wet weight (ww)). The mean total PCB concentration in eggs was 15.12 microg/kg ww. Of PAHs tested for, residues of 1- and 2-methylnaphthalene and naphthalene were found in 100% of the eggs, at mean concentrations of 0.36-0.89 microg/kg ww.     

Application of real time PCR determination to assess interanimal variabilities in CYP1A induction in the European flounder (Platichthys flesus)

In both laboratory experiments and field investigations with fish a large interanimal variability in CYP1A expression has been observed which may be attributed to variations in environmental inducer exposure and/or inducer response. We are carrying out laboratory investigations to assess the contribution of a potential genetic component in inducer response of flounder (Platichthy sflesus) CYP1A to PCB exposure and in this paper we report development of a sensitive quantitative RT-PCR procedure (real time PCR) where accumulation of the intercalated dye SYBR Green I is followed during cycling. Preliminary experiments using this procedure with artificially reared Arochlor 1254-treated flounders showed large interanimal differences in response for a single family group indicating that variability does have a genetic basis.     

H2O-H2SO4 system in Venus' clouds and OCS, CO, and H2SO4 profiles in Venus' troposphere

A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer. The position of the lower cloud boundary and profiles of the H2O and H2SO4 vapor mixing ratios and of the H2O/H2SO4 ratio of sulfuric acid aerosol and its flux are calculated as functions of the column photochemical production rate of sulfuric acid, phi H2SO4. Variations of the lower cloud boundary are considered. Our basic model, which is constrained to yield fH2O (30 km) = 30 ppm (Pollack et al. 1993), predicts the position of the lower cloud boundary at 48.4 km coinciding with the mean Pioneer Venus value, the peak H2SO4 mixing ratio of 5.4 ppm, and the H2SO4 production rate phi H2SO4 = 2.2 x 10(12) cm-2 sec-1. The sulfur to sulfuric acid mass flux ratio in the clouds is 1 : 27 in this model, and the mass loading ratio may be larger than this value if sulfur particles are smaller than those of sulfuric acid. The model suggests that the extinction coefficient of sulfuric acid particles with radius 3.7 micrometers (mode 3) is equal to 0.3 km-1 in the middle cloud layer. The downward flux of CO is equal to 1.7 x 10(12) cm-2 sec-1 in this model. Our second model, which is constrained to yield fH2SO4 = 10 ppm at the lower cloud boundary, close to the value measured by the Magellan radiooccultations, predicts the position of this boundary to be at 46.5 km, which agrees with the Magellan data; fH2O(30 km) = 90 ppm, close to the data of Moroz et al. (1983) at this altitude; phi H2SO4 = 6.4 x 10(12) cm-2 sec-1; and phi co = 4.2 x 10(12) cm-2 sec-1. The S/H2SO4 flux mass ratio is 1 : 18, and the extinction coefficient of the mode 3 sulfuric acid particles is equal to 0.9 km-1 in the middle cloud layer. A strong gradient of the H2SO4 vapor mixing ratio near the bottom of the cloud layer drives a large upward flux of H2SO4, which condenses and forms the excessive downward flux of liquid sulfuric acid, which is larger by a factor of 4-7 than the flux in the middle cloud layer. This is the mechanism of formation of the lower cloud layer. Variations of the lower cloud layer are discussed. Our modeling of the OCS and CO profiles in the lower atmosphere measured by Pollack et al. (1993) provides a reasonable explanation of these data and shows that the rate coefficient of the reaction SO3 + CO --> CO2 + SO2 is equal to 10(-11) exp(-(13,100 +/- 1000)/T) cm3/s. The main channel of the reaction between SO3 and OCS is CO2 + (SO)2, and its rate coefficient is equal to 10(-11) exp(-(8900 +/- 500)T)cm3/s. In the conditions of Venus' lower atmosphere, (SO)2 is removed by the reaction (SO)2 + OCS --> CO + S2 + SO2. The model predicts an OCS mixing ratio of 28 ppm near the surface.     

Spectroscopy of Mars from 2.04 to 2.44 micrometers during the 1993 opposition: absolute calibration and atmospheric vs mineralogic origin of narrow absorption features

We present moderate-resolution (lambda/delta lambda = 300 to 370) reflectance spectra of Mars from 2.04 to 2.44 micrometers that were obtained at UKIRT during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO(2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 micrometers). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 micrometers) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 micrometers may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates or (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals.