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George S. Young and John W. Winchester

Abstract

Peak concentrations of aerosol sulfur in Tampa, Florida may be the result of either regional-scale transformation and transport processes or local-scale transport from nearby air pollution sources. The existence of the latter has been demonstrated in Tampa through correspondence of sulfur with sea breeze circulation patterns and the resulting chloride concentration maxima (which serve as indicators of the marine aerosol), vanadium concentration maxima (which indicate times of high concentrations of certain plume constituents), and the locations of sources favorable for high concentrations of air pollution-derived sulfate during occurrences of the sea breeze. The analysis indicates that locally derived sulfate in the Tampa atmosphere, which may be less abundant than sulfate due to regional-scale processes, can be identified by the use of combined meteorological and chemical tracer interpretation.

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James O. Pilotte, John W. Winchester, and J. William Nelson

Abstract

By means of multiple linear regression analysis of a suite of more than 10 000 concentration measurements, of 14 elements at 11 sampling stations every 2 h over the course of a week in July 1975, Pb was found to be correlated in time most strongly with Br, secondarily with Zn, and also with K and Fe. At one station some Pb variation was apparently independent of other elements. On this basis and on the basis of wind directional relationships among the elements, at least four different components of Pb in the St. Louis aerosol may be identified.

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A. Nelson Dingle, Donald F. Gatz, and John W. Winchester

Abstract

In an effort to determine whether it is feasible to use tracer techniques in the study of circulations and rain scavenging processes in severe convective storms, a pilot experiment using indium as tracer was conducted. A total of 200 gm of indium was released over a period of 21 min into the updraft feeding a relatively small convective system. The tracer was released by means of pyrotechnic flares from an airplane flying at about 3200 ft altitude. The rainfall from the system was sampled at the ground by means of an array of samplers placed and recovered by two mobile units. Analysis of the samples compared against analyses of untagged rain samples and reagent backgrounds of indium distinctly indicates the presence of tracer indium in a reasonable distribution pattern.

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Donald F. Gatz, A. Nelson Dingle, and John W. Winchester

Abstract

In a test of the use of indium as a particulate atmospheric tracer, both tagged and untagged rain showers were sampled at ground level in Oklahoma during May 1967. In 29 samples of untagged rain 6±3 nanograms of In per liter were found, indicating a natural background somewhat above the reagent blank of about 2 ng liter−1. After aircraft injection at cloud base of 200 gm of indium, as finely divided particles from pyrotechnic flares, a maximum of 40 ng liter−1 was found in the rain, and a pattern of localization of the tracer indium was revealed in an array of 14 samplers spaced over 11 km. The procedure for analysis began in the field with 1) addition of HC1 to the polyethylene samplers before rain was collected to ensure solubility of the tracer, 2) filtration to remove suspended solids, 3) addition of lanthanum internal standard, Fe+++, and NH3 to each 1-liter sample to precipitate In and La with Fe(OH)3, and 4) membrane filtration of the Fe(OH)3. At The University of Michigan the procedure continued with 5) reactor neutron activation of the filters, 6) separation of In from La by isopropyl ether extraction from HBr solution, and 7) assay of In and La radioactivities by β and γ, counting, respectively. The sensitivity of the method is determined by the natural background of the indium found.

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