Elasticity of orthoenstatite

Elastic constants of orthoenstatite have been determined from Brillouin-scattering measurements. They are c₁₁ = 2.247, c₂₂ = 1.779, c₃₃ = 2.136, c₄₄ = 0.776, c₅₅ = 0.759, c₆₆ = 0.816, c₂₃ = 0.527, c₃₁ = 0.541 and c₁₂ = 0.724 Mbar. Each elastic constant is uniquely defined by the data. Acoustic velocities measured for two directions ultrasonically on the same samples are within 1% of those determined from Brillouin-scattering spectra.     

The chemical composition of a Greenland glacier

Chemical analyses on water from dated strata of a south Greenland permanent ice sheet revealed that there is a larger amount of sulfate in samples accumulated during the past decade than in those 60 or more years older. This increase is attributed to combustion of fossil fuel. With the exception of mercury, cadmium and possibly copper, the heavy metal distributions in the glacial waters are similar to those in atmospheric dusts. Previously reported higher mercury values in recently deposited strata were not confirmed.     

MELIMEX,an experimental heavy metal pollution study: Particle size distributions in limno-corrals

The particle size distributions in three limno-corrals, located in Baldeggersee, Switzerland, have been determined by means of a Zeiss Micro-Videomat image analyzer as a function of depth and time. The distributions were measured biweekly over a period of 1 year at depths of 0 m, 2.5 m, 5 m, 7.5 m and 10 m (=above bottom). Two of the limno-corrals were charged with heavy metals, whereas the third was uncharged and served as a reference. The shape of the distributions as well as the particle concentrations in the uncharged container did not differ from the ones in the charged limno-corrals. The distributions were found to be self-preserving and independent on heavy metal load, time, depth and particle concentrations. As an average, the dependence of the distributions on the particle diameter was found to be ?1.5 to ?2.5.     

A) A. I. H. S. / A) I. A. S. H.

Abstract

In the Southwestern intermountain and high plains areas, precipitation is seasonal, with the major part of the rainfall occurring in the summer. Most winter precipitation occurs as low-intensity rain or snow along slow-moving cold fronts. Most summer precipitation occurs as short-duration, high-intensity thunderstorms from purely convective buildup or from convective cells developing along a weak fast-moving cold front. Almost all runoff occurs from the summer convective storms.

Since runoff-producing precipitation is of primary interest at the Southwest Watershed Research Center, Agricultural Research Service, Tucson, Arizona, the convective storms have been most thoroughly analyzed. Duration, intensity, areal extent, movement, character, and return frequencies for varying volumes and intensities of these convective storms are analyzed from records from dense networks of recording rain gages in four study areas in Arizona and New Mexico. The primary study areas are the 58-square-mile Walnut Gulch Experimental Watershed at Tombstone, Arizona, and the 67-squaremile Alamogordo Creek Watershed near Santa Rosa, New Mexico. Three “record” storms of differing character occurring in 1960 and 1961 on Alamogordo Creek Watershed and one “record” storm in 1961 on the Wlanut Gulch Watershed are analyzed and compared in detail.     

Heavy metal retention in secondary precipitates from a mine rock dump and underlying soil, Dalarna, Sweden

This study investigates the retention of heavy metals in secondary precipitates from a sulfidic mine rock dump and underlying podzolic soils by means of mineralogical and chemical extraction methods. The rock dump, which is at least 50 years old, consists of a 5–10-cm-thick leached zone and an underlying 110–115-cm-thick accumulation zone. Optical microscopy and electron microprobe analyses confirm that pyrrhotite weathering has proceeded much further in the leached horizon relative to the accumulation horizon. The weathering of sulfides in the leached zone has resulted in the migration of most heavy metals to the accumulation zone or underlying soils, where they are retained in more stable phases such as secondary ferric minerals, including goethite and jarosite. Some metals are temporarily retained in hydrated ferrous sulfates (e.g., melanterite, rozenite). Received: 28 October 1996 · Accepted: 24 February 1997     

Formation of the Ca ii K-line core with arbitrary temperature minima

The formation of the solar Caii K-line core is studied under the assumption of a two component chromosphere for many atmosphere models, which are tested by comparing observed and calculated average intensity profiles at several places on the solar disk. Non-LTE-line profile calculations are made using model atoms of two and three bound levels while the value and depth of the temperature minimum and turbulent velocity gradient are varied. A critique of several broad types of models is provided.Limb darkening of the entire core, a K1 radiation temperature of 4300 K and increasing limbward separation of the K2 peaks are predicted by a combination of a cool component, covering 90% of the solar disk, and a hot component, representing the bright calcium network. The optimum cool component is characterized by a 4200 K temperature minimum and low ( 1 km/sec) microturbulent velocities. The hot component begins its outward temperature rise in the photosphere at 4300 K and is never more than 500 K hotter than the cool component.Publications of the Goethe Link Observatory, Indiana University, No. 116.Presently at New Mexico State University, Las Cruces, New Mexico.     

A source for hyperbolic cosmic dust particles

Earlier analyses of the Pioneer 8 and 9 experimental meteoroid data have shown that the detectors on these two spacecraft are intercepting meteoroids with hyperbolic orbital parameters. It is shown in this paper that these results are entirely consistent with and, indeed, to be expected from other observations of the interplanetary meteoroid complex. Collisional breakup of meteoroids and post-collision radiation pressure modification of their orbits is found to be a sufficient cause for the observed results. Details of the calculations as well as of the results are presented.