Tons Of Dust Research Articles

Vertical and areal distribution of Saharan dust over the western equatorial north Atlantic Ocean

Aerosol measurements were made as a part of the Barbados Oceanographic and Meteorological Experiment (Bomex) during May, June, and July 1969. Maximum dust concentrations occurred between the altitudes of 1.5 km and 3.7 km, a region which we call the Saharan air layer. The average concentration of mineral aerosol within this layer was 61 μg m−3; in contrast, the average concentration in the low-level air was 22 μg m−3. These dust concentrations are comparable to those found in continental surface air. Because of the presence of a strong inversion at the base of the Saharan layer, sea salt was confined to te lower altitudes where the average concentration was 10 μg m−3. Thus, sea salt appears to be a relatively minor constituent of the trade wind aerosol during much of the year. On the basis of these measurements and of a model describing the movement of Saharan air outbreaks, we estimate that 25 to 37 million tons of dust are transported through the longitude of Barbados each year. This quantity of dust is sufficient to supply all the material required to maintain the present rate of pelagic sedimentation across the entire northern equatorial Atlantic Ocean.

Fundamentals of Electrode Rapping in Industrial Electrical Precipitators

The electrodes in industrial precipitators collect many tons of dust daily, and the efficient transfer of this dust burden to the hoppers is a challenging problem in mechanical engineering. Many varieties of devices have been tried; hammers, vibrators, scrapers, water flushing, gas blasting, etc. Impact devices for this purpose are usually called “rappers.” Laboratory experiments described in this paper show that normal (perpendicular) rapping is more effective than shear rapping; that thick dust layers are more easily removed by rapping than thin ones; that rapping becomes easier with increasing temperature, within limits; and that the electrostatic forces acting upon the precipitated dust layer play an important role. Quantitative data are shown graphically. The relation of these results to previous studies by other investigators is discussed.

Pollen Carried by Dust Storm

MR. O. C. DURHAM, chief botanist of the Abbott Laboratories in North Chicago, exposed collecting slides through the period of the remarkable dust storm recently experienced in the United States. His collections, as a result of the examination of these slides, indicate a fall of some 34-7 tons of dust per square mile, of which no less than 3-4 tons would be represented by oak pollen. This percentage of pollen certainly seems a striking phenomenon and has its interest in connexion with the use made of pollen distribution in strata of vegetable remains, as an indication of the vegetation in these areas at the period when the remains were deposited. Mr. Durham's observations are reported by Science Service, Washington, D.C., under date May 14.