Earth discontinuities

This suggests that the second derivatives have a discontinuity at places where the density changes abruptly. In particular, a discontinuity takes place at the earth s surface. 

Pickett DA, Murrell MT, Williams RW (1994) Determination of femtogram quantities of protactinium in geologic samples by thermal ionization mass spectrometry. Anal Chem 66 1044-1049 Plagnes V, Causse C, Genty D, Pateme M, Blamart D (2002) A discontinuous climatic record from 187 to 74 ka from a speleothem of the Clamouse Cave (south of France). Earth Planet Sci Lett 201 87-103 Polyak VJ, Asmerom Y (2001) Late Holocene climate and cultural changes in the southwestern United States. Science 294 148-151... 

Chakraborty S., Knoche R., Schulze H., Ruble D.C., Dobson D., Ross N.L., and Angel R.J. (1999) Enhancement of cation diffusion rates across the 410-kilometer discontinuity in Earth s mantle. Science 283, 362-365. 

Figure 22 shows the salt effects for monovalent and divalent cations (alkali and alkali earth metals) chlorides. For all these salts, the phase transitions took place reversibly and were discontinuous as functions of salt molality. The efficiency of salts in contracting gels was almost the same for alkali metals chlorides (monovalent cations) except Li+, whereas it was slightly dependent on alkali earth metals (divalent cations) in inverse order of ionic radii, Mg2+ < Ca2+ < Sr2+ < Ba2+. 

We have just seen that in the case of the rare earths the previously unoccupied, well-shielded 4/ shell is filled with increasing atomic number. The belated filling of the 4/ shell gives rise to the well know lanthanide contraction. The effect of the lanthanide contraction is seen even in Tc and Re. This contraction is characteristic of both the metals and the cations in different oxidation states. Similar curves to Pig. 7 with discontinuities at Eu and Yb are obtained by plotting atomic radii and ionic radii against atomic number of the rare earths. The ionic radii of the rare earths [181] in various oxidation states are given in Table 7. The ionic radii of the divalent ions of Sm and Eu compare closely with the Ca2+ and Sr2+. 

Natural Pollution of the Oceans, Frequently overlooked is what may be termed natural 1 pollution, which, when coupled with artificial (anthropogenic) pollution, contributes to the sum total of all pollutants found in fresh and ocean waters worldwide. Deep fissures in the ocean floor, fumaroles, and seamounts (underwater volcanoes) release megatons of sulfur-laden and other noxious gases into ocean water other discontinuities in the ocean basins release vast quantities of crude oil and other hydrocarbons. Surface volcanoes are major contributors to atmospheric pollution, much of which ultimately affects Earth s hydrosphere. The present dissolved solids content of the oceans represents natural water pollution that has taken place ever since the land masses rose above sea level—through a constant erosion of soil. 

Figure 3.1 A cross section of the crusts, rigid upper mantle, and plastic mantle asthenosphere of the Earth. The Mohorovicic Discontinuity is the boundary between the crust and upper mantle. The lithosphere includes the crusts and the upper mantle.

The chemical composition of the Lower Mantle below 670 km is essentially unknown. It has often been assumed to be the same as the Upper Mantle with the seismic discontinuity at 670 km representing a phase change to denser polymorphs rather than a chemical boundary (Liu and Bassett, 1986). However, some models of the Earth s interior suggest that the Mantle is stratified with the Upper Mantle and Lower Mantle convecting separately, leading to compositional density differences between these two regions. There is a commonly held view that the Lower Mantle has a higher Fe/(Mg+Fe) ratio than the Upper Mantle (Liu and Bassett, 1986 Jeanloz and Knittle, 1989). 

It is possible to include yttrium among the rare earths, because of its properties, which are rather like those of some of the rare earths. For instance, when we express a physical property of the sulfides as a function of the ionic radii of the metals, the yttrium sulfide normally lies among the rare earth series, without any discontinuity, between dysprosium and erbium sulfides. 

Although one often finds hypochlorous and chlorous acids written HCIO and HC102, this is unfortunate and should be discontinued since they are actually HOC1 and HOCIO. This is not a purely pedantic matter since in studies of gas phase kinetics in the earth s ozone layer, the distinction between the unstable isomer, HCIO, and HOC1 is significant. Hypochlorous acid HOC1 is 280 kJ mol-1 more stable than HCIO. 

In real-time, shallow earth profiles of dielectrical discontinuities related to subsurface conditions such as moisture content lithology, bedding, voids, fractures, man-made objects. Can be used to detect buried plastic containers artd areas of excavation boundaries. 

From seismic evidence, the density and elastic properties of the Earth are known to change markedly at the boundary between the mid-mantle (the transition zone) and the lower mantle. The 670-km discontinuity has been attributed to a pressure-induced transformation of (Mg,Fe)2Si04 to a fine mixture of the above silicate perovskite and magnesio-wiistite. 

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