Showing papers in "Environmental Science & Technology in 1974"

Trace elements in fly ash: dependence of concentration on particle size

Abstract: Concentrations of 25 elements in fly ash emitted from a coal-fired power plant were measured as a function of particle size using spark source mass spectroscopy, optical emission spectrography, atomic absorption spectroscopy, and x-ray fluorescence spectroscopy. Of these elements, the concentrations of Pb, Tl, Sb, Cd, Se, As, Zn, Ni, Cr, and S increased markedly with decreasing particle size. To account for the trace element concentration dependence on particle size, a mechanism is proposed involving high-temperature volatilization of a species containing the trace element followed by preferential condensation or adsorption onto the smallest particles. Environmental significance of the measurements is discussed.

Response of commercial chemiluminescent nitric oxide-nitrogen dioxide analyzers to other nitrogen-containing compounds

Abstract: Commercial chemiluminescent oxides of nitrogen analyzers employing carbon or molybdenum converters are nonspecific for determination of nitrogen dioxide (NO/sub 2/) The instruments not only measure NO/sub 2/, but also simultaneously respond nearly quantitatively to peroxyacetyl nitrate (PAN), and a variety of other organic nitrates and nitrites Furthermore, they respond nonquantitatively to compounds such as nitroethane and nitric acid The implications of these observations are not serious for most ambient air analyses where the concentrations of the interfering nitrogenous compounds are low relative to NO/sub 2/ levels However, for highly quantitative ambient air or smog chamber measurements under circumstances where relatively low concentrations of NO/sub 2/ occur simultaneously with high concentrations of PAN and other nitrogen-containing compounds, corrections for interference by these compounds can be significant In the absence of such corrections, the NO/sub x/ mode of commercial chemiluminescent analyzers must be viewed to the good approximation as measuring total gas phase ''oxides of nitrogen,'' not simply the sum of NO and NO/sub 2/

Hydrocarbon composition of urban air pollution

Abstract: AIR SAMPLES WERE COLLECTED AT SITES IN LOS ANGELES AND NEW YORK TO EVALUATE COMPOSITIONAL DETAIL OF THE HYDROCARBONS AND OXIDES OF NITROGEN. THE COMPOSITIONAL DETAILS PROVIDE A WEALTH OF INFORMATION ALLOWING FOR THE ESTIMATION OF SOURCE CONTRIBUTION AND PHOTOCHEMICAL POTENTIAL OF AN AMBIENT ATMOSPHERE. THE NEED TO INVENTORY AN AMBIENT ATMOSPHERE FOR SOURCE CONTRIBUTION IS IMPORTANT FOR EVALUATING CONTROL STRATEGY REQUIRED TO MEET AIR QUALITY STANDARDS. THE MANUSCRIPT DESCRIBES TWO METHODS FOR ESTIMATING VEHICULAR HYDROCARBONS IN AN AMBIENT ATMOSPHERE.

Distribution of atmospheric mercury species near ground

Abstract: A recently developed technique makes possible the routine analysis of atmospheric samples for particulate and volatile mercury. The volatile fraction can be analyzed for several chemical species. This work presents the results of some Tampb Bay area analyses and diurnal studies of atmospheric mercury speciation. The mercury in air in the area investigated was primarily volatile (>90%) and was composed of significant proportions of mercury (II)-type compounds, methylmercury (II)-type compounds, and elemental mercury. Dimethylmercury was rarely observed. Results were quite variable suggesting a variety of sources and irregular wind transport processes. The data indicate that background mercury concentrations and the percentage distribution of mercury species in air in a local area may be established by mercury emanations from the ground or from adjacent bodies of water.

Formation of nitrosyl chloride from salt particles in air

Abstract: The reaction of sodium chloride particles with 01-15 reacts with sodium chloride to form nitrosyl chloride, a corrosive gas The reaction is rapid, but surface area dependent Free energy calculations indicate a favorable free energy change and a large equilibrium constant This reaction is important in studying the chemical and physical interactions of halide aerosols in atmospheres containing no2 (3 graphs, 17 references)

Effects of relative humidity and temperature on iron-catalyzed oxidation of sulfur dioxide in atmospheric aerosols

Abstract: The roles of relative humidity and temperature in promoting the iron-catalyzed oxidation of atmospheric sulfur dioxide to acid mist in urban atmospheres are quantitatively evaluated. The oxidation rate increases rapidly with increasing relative humidity, and decreases by an order of magnitude for an increment of 5 c in temperature. A qualitative agreement exists between estimated and observed rates of SO/sub 2/ oxidation in the atmosphere. (24 references, 1 table)