Wind tunnel modeling of small-scale meteorological processes

After introductory remarks on similarity laws to be satisfied in wind tunnel experiments simulating small-scale meteorological processes, mean and turbulence characteristics of wind tunnel boundary layers are presented and compared with the characteristics of the atmospheric boundary layer. The results are used to evaluate the possibilities and limitations of physical modeling of pollutant dispersion in general. In the second part of the paper, the potential of wind tunnels to solve micro-meteorological problems of real practical interest will be demonstrated. The example involves the investigation of the effects of building downwash on ground-level concentrations for flue gases discharged from natural draft wet cooling towers.     

Volatile contents of phlogopite micas from South African kimberlite

Phlogopite micas from nodules in South African kimberlites were analyzed for major elements with the electron microprobe and for volatile contents by high temperature mass spectrometry. The micas are from primary- (deformed) and secondary- (undeformed) textured grains in perodotite xenoliths, glimmerites, MARID (mica-amphibole-rutile-ilmenite-diopside) suite nodules and a mica megacryst. The major element and volatile contents of micas exhibiting these modes of occurrence overlap to a greater extent than indicated in previous studies. Concentrations of volatile species occupying structurally defined crystallographic sites (H₂O, F, Cl) are greater for many of the micas than predicted on the basis of the mica formula, particularly for the glimmerite and MARID suite samples. A correlation exists between micas with tetrahedral and octahedral cation deficiencies and those with excess H₂O, F and Cl. Substitution of H⁺ for tetrahedral and possibly octahedral cations may be responsible for the excess H₂O in these micas. Except for one sample, the major element and volatile data for the peridotite, glimmerite and MARID suite micas indicate that they crystallized at oxygen fugacities below the quartz-fayalite-magnetite buffer. F and K₂O are in the correct proportion in the micas to provide the source for these elements in alkali basalts, but not in mid-ocean ridge basalts. Kaersutite amphibole is a more likely source of potassium and fluorine in mid-ocean ridge basalts.     

Micro Computers Applied to Ground Water Monitoring and Testing

Micro computers have been demonstrated to be a most valuable, cost-effective means of long- and short-term data acquisition for ground water investigations and installations. A system can readily be assembled for the cost of labor saved in the field, or for the same cost as other conventional instruments, which perform only a fraction of the functions of the computer system
Documented in this article are systems which have been developed and used for simultaneous monitoring of several wells during aquifer tests, and systems installed for long-term monitoring of piezometric surface fluctuations. Both systems can be contained in a small suitcase or insulated cooler. Specific features of the systems include multiple channel capacity, one-month maintenance period, variable computer controlled reading intervals, magnetic tape data storage, data reduction and analysis capabilities while maintaining monitoring, graphic display of time and measurements, hard copy capability and barometric pressure change corrections.
Other applications are examined for the complete control of pumping tests, including pumping rate; in situ permeability tests; monitoring changes; and even strain. The pressure transducer system may also be applied for river gauging and current measurement.     

Changes in current regime and turbidity in response to a freshwater pulse in the eastmain estuary

In September 1984, the freshwater input to the Eastmain River (James Bay, Canada) was increased by a factor of 50 over a 6-d period during a controlled reservoir discharge. Changes to the current, salinity and turbidity regimes were monitored during the peak runoff. Estuarine salinity values fell rapidly with increasing mean flow, as did the amplitude of the semi-diurnal tidal currents. A large increase in bottom shear stress dispersed the settled suspension layer into the water column, raising concentrations of suspended matter in the estuary by a factor of 4 in 3 d. The peak values exceeded 150 mg I^?1. This led to erosion of the river silt deposits, with the export of an estimated 6 × 10⁴ metric tons of sediments. After the reduction of discharge, current values returned to their normal range within a day, whereas upstream salinity intrusion occurred at a slower rate. Horizontal diffusivities of about 100 m² s^?1 were required to match the observed lag.     

Occurrence of juvenile Atlantic sturgeon,Acipenser oxyrhynchus,in the upper tidal Delaware River

Eighty-nine juvenile Atlantic sturgeon,Acipenser oxyrhynchus oxyrhynchus, including 10 recaptures, were collected, tagged and released in the upper tidal Delaware River between July 1981 and December 1984. All were captured in the river channel between Roebling and Trenton, New Jersey, using bottom-set experimental gill nets during daylight hours. The species was present from July through December and collected in increased numbers in the past two years. The fork lengths ranged from 284 to 862 mm (mean±SD = 516 mm±106 mm) and the weights from 140 to 4,250 g (mean±SD = 1,369 g±815 g). Ten juvenile Atlantic sturgeon were recaptured between September 1983 and December 1984 and were at large from one to 418 d. Recapture data suggest that these sturgeon utilize this area annually from July through December, possibly as a nursery. Juvenile Atlantic sturgeon appear to utilize the upper tidal portion of the Delaware River for a much longer period of time and at lower temperatures than in other river systems.     

Seasonal control of the Saint-Lawrence maximum turbidity zone by tidal-flat sedimentation

The core of the turbidity maximum zone in the Saint-Lawrence Estuary is located in the North Channel and oscillates in front of the large (3×10⁶ m²) intertidal flats and marshes of Cap Tourmente. It is shown that seasonal fluctuations in the intensity and the position of this core are mainly determined by suspended sediment exchanges between the channel and the marshes. Fine sediments, most of them found 20 km downstream in the channel off Cap Maillard in late winter and early spring, are advected upstream over the flats during the summer months by the tide. The deposition, favored by marsh plant growth, reaches 5×10⁵ metric tons in three months. A period of intense erosion, at a mean rate of 4,500 metric tons per tide, coincides with the destruction of the plant cover by migratory geese. The material removed fills up the Chenal de l’Île d’Orléans upstream and is flushed back into the water column during the next spring freshette. This rotating seasonal sediment circulation, although very localized, exerts a major influence on the distribution and storage time of suspended particles in the upper estuary.     

Thaumasite from the Tschwinning mine,South Africa

Summary Thaumasite from the manganese mine of Tschwinning, South Africa, has the formula Ca_3.097 Si_1.062OH_6.372(CO₃)_0.994(SO₄)_1.000·11.596 H₂O. Unit cell parameters (a=11.013(2) Å,c=10.379(5) Å,V=1090.1(6) ų) and refraction indices (n_e=1.458(2),n _o=1.498(2)) compare well with the best ones available in the literature. The IR spectrum and DT-TG profiles are given. Contradictions between the IR spectrum, a recent structural refinement and the DT-TG are discussed, but cannot be explained satisfactorily.

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Thaumasit aus der Mangan-Mine von Tschwinning, Süd-Afrika

Zusammenfassung Thaumasit aus der Mangan-Mine von Tschwinning, Süd-Afrika, besitzt die Formel Ca_3.097 Si_1.062OH_6.372(CO₃)_0.994(SO₄)_1.000·11.596 H₂O. Die Parameter der Elementarzelle (a=11.013(2) Å,c=10.379(5) Å,V=1090.1(6) ų) und die Brechungsindizes (n _e=1.458(2),n _o=1.498(2)) zeigen gute Übereinstimmung mit verfügbaren Literaturdaten. Es werden ein IR-Spektrum und DT-TG-Profile präsentiert. Gegensätze zwischen dem IR-Spektrum, einer neueren Strukturverfeinerung und dem DT-TG werden diskutiert, können jedoch nicht zufriedenstellend erklärt werden.

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With 2 Figures     

Deformation produced by oblique rifting

With oblique rifting, both extension perpendicular to the rift trend and shear parallel to the rift trend contribute to rift formation. The relative amounts of extension and shear depend on α, the acute angle between the rift trend and the relative displacement direction between opposite sides of the rift. Analytical and experimental (clay) models of combined extension and left-lateral shear suggest the fault patterns produced by oblique rifting. If α is less than 30°, conjugate sets of steeply dipping strike-slip faults form in rifts. Sinistral and dextral strike-slip faults trend subparallel and at large angles to the rift trend, respectively. If α is about 30°, strike-slip, oblique-slip and/or normal faults form in rifts. Faults with sinistral and dextral strike slip trend subparallel and at large angles to the rift trend, respectively. Normal faults strike about 30° counterclockwise from the rift trend. If α exceeds 30°, normal faults form in rifts. They have moderate dips and generally strike obliquely to the rift trend and to the relative displacement direction between opposite sides of the rift. If α equals 90°, the normal faults strike parallel to the rift trend and perpendicularly to the displacement direction.The modeling results apply to the Gulf of California and Gulf of Aden, two Tertiary continental rift systems produced by combined extension and shear. Our results explain the presence and trends of oblique-slip and strike-slip faults along the margins of the Gulf of California and the oblique trend (relative to the rift trend) of many normal faults along the margins of both the Gulf of California and the Gulf of Aden.