Metal binding capacity of selected maine surface waters

Concentrations of Ca, Cd, Cu, Fe, and Pb and binding capacities for Cd, Cu, and Pb were determined for water samples collected from 12 lakes in southwestern Maine using atomic absorption and ion-selective electrodes, respectively. Surface waters in this area are soft and characterized by low pH. Some lakes were highly colored with refractory organics, whereas others had very low organic carbon concentrations. Both Cu and Pb concentrations were positively correlated with organic carbon content. Copper and Pb binding capacities were significantly correlated with organic carbon content, whereas Cd binding capacity was positively correlated with pH, but not with organic carbon. Surface water binding capacity for Pb was greater than that for Cu or Cd. More than 99% of the Ca from all waters studied was removed onto cationic exchange resins. Less than 1% of the total Cu existed as cationic species in highly humic waters, whereas as much as 65% existed as cationic species in less huic waters. Conversely, more than 99% of the Cd present in humic waters existed as cationic species, whereas as little as 50% existed as cationic species in less humic, more alkaline waters. These correlative studies indicate that binding by organic carbon is important for both Cu and Pb in this area and must be considered in models of trace metal speciation. However, Cd binding in the same waters is not correlated with organic carbon, which does not need to be considered in speciation models for Cd.     

Variability and anisotropy of mechanical properties of the pittsburgh coal seam

SummaryVariability and Anisotropy of Mechanical Properties of the Pittsburgh Coal Seam Results of an experimental program to determine the vertical variation of material stiffness and strength of an important coal seam are presented, with the aim of providing information for realistic modeling for purposes of analysis. The seam is divided into four zones, and data from each are evaluated statistically. It is concluded that this seam contains two zones with measurably different properties, which, however, are small compared to the observed scatter of data.

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ZusammenfassungStreubereich und Anisotropie der mechanischen Eigenschaften des Pittsburgher Kohleflözes Es werden Ergebnisse eines Versuchsprogramms zur Bestimmung der senkrechten Veränderung der Steifheit und Festigkeit des Materials in einem wichtigen amerikanischen Kohlenflöz präsentiert, um Unterlagen für realistische Modellbildung zum Zwecke der Spannungsberechnung zu liefern. Der Flöz ist in vier Zonen unterteilt, deren Daten statistisch untersucht wurden. Es ergab sich, daß dieser Flöz zwei Zonen mit meßbar unterschiedlichen Eigenschaften enthält; diese Unterschiede sind aber klein im Vergleich zur Streuung der einzelnen Daten.

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RésuméVariabilité et anisotropie des propriétés mécaniques du banc de charbon de Pittsburgh On a analysé, par échantillons, la variabilité de la résistance et du module d'un banc de charbon épais, avec la profondeur. Le but de l'étude est d'obtenir des valeurs réalistes qui puissent être utilisées dans une analyse par méthodes numériques. Le banc est divisé en quatre zones, et les résultats sont analysés de façon statistique, séparément pour chaque zone. On a conclut que ce banc contient deux zones dont les propriétés mécaniques diffèrent. Cependant ces différences ne dépassent pas l'ordre de grandeur des écarts dans les observations sur chaque zone.

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With 10 Figures     

57Fe NCR of Fe phases in “magnetic cassiterites”

A pyralspite garnet from an anomalously magnetic concentrate of a pegmatitic cassiterite ore has been investigated using ⁵⁷Fe nuclear gamma-ray resonance spectroscopy. The quadrupole splitting and isomer shift values of 3.6 mm/s and 1.4 mm/s, respectively, are among the largest observed for Fe²⁺ ions and indicate a very low covalency of the dodecahedral Fe²⁺ — O²-bonds. These data support the more recent and lower value (10.2–10.1 kcal/ mole) of White and Moore (1972) for the CFSE of the dodecahedral Fe²⁺ ion and suggest that the CFSE should be a useful approximation to the site preference energy of Fe²⁺ for this site.     

Drag coefficient and roughness length determinations on an Alaskan Arctic Coast during summer

Field data collected over land and water near Point Lay, Alaska, yielded determinations of the aerodynamic roughness lengths and drag coefficients over three locations on an arctic barrier island and over the Chukchi Sea. The agreement between the results over the sea and previous published results from data taken at approximately the same latitude in the Beaufort Sea is excellent.     

Detailed observational study of a weak Echo region

High resolution 3-cm weather radar was used to observe the three dimensional structure of a weak echo region of a severe convective storm in northern Minnesota, U.S.A. Observations show that a seemingly steady-state updraft in the lower portion of the storm broke into an unsteady structure in the upper levels. This is interpreted as indicating that precipitation loading gradually decelerated the upper reaches of the updraft, resulting in periodic breakout of a new updraft core on the inflow side. This periodic behavior of the updraft may be related to hailstreaks and what has been termed the multi-celled storm.     

Simulating the moderating effect of a lake on downwind temperatures

A steady-state, two-dimensional numerical model is used to simulate air temperatures and humidity downwind of a lake at night. Thermal effects of the lake were modelled for the case of moderate and low surface winds under the cold-air advective conditions that occur following the passage of a cold front. Surface temperatures were found to be in good agreement with observations. A comparison of model results with thermal imagery indicated the model successfully predicts the downwind distance for which thermal effects due to the lake are significant.