Halstead Harrison

Oxidation of sulfur dioxide by oxygen and ozone in aqueous solution: A kinetic study with significance to atmospheric rate processes☆

Abstract The oxidation rates of SO2 by O2 and O3 have been studied in buffered aqueous solutions at pH between 4 and 12, temperatures between 5 and 25°C, oxygen partial pressures between 0.11 and 1.0 atm., and ozone partial pressures between 0.2 and 1.0 ppm. For the O2 reaction we observe oxidation rates of the form: d[SO 4 2− ] dt = {k 1 + k 2 [H + ] 1 2 + k3Po2[H+−1[SO2−3] with k1 = (4.8 ± 0.6) × 10−3s−1 k 2 = (8.9 ± 1.0) s −1 M − 1 2 k3 = (3.9 ± 0.6) × 10−12s−1 M atm−1, all at 298 K with a multiple correlation coefficient (R2) = 0.73. In acidic solutions this expression displays weak temperature dependence and zero-order O2 dependence. For the O3 reaction we observe oxidation rates of the form: d[SO 2− 4 ] dt = k 4 K HO 3 P O 3 [HSO − 3 ][H + ]−0.1±0.02 with K4 = (4.4 ±2.0) × 104M−0.9S−1KHO3 = 0.0123 M atm−1, both at 298 K, with R2 = 0.38. A simpler expression strictly proportional to bisulfite gives k5 = (1.6 ± 0.1) × 105Ms−1 with R2 = 0.33. We observe the O2 and O3 rate to be very nearly equal in neutral or weakly acidic solution. In clouds over the U.S. and Europe, with pH ⪝ 5 and O 3 ⪞ 50ppb , the O3 reaction should be important.

Atmospheric Effects of Pollutan: Pollutants which affect clouds are most likely to produce modifications in weather and climate.

We have argued that aerosols are probably the principal agents by which pollutants may affect weather and climate. They are most likely to act by influencing the structure and distribution of clouds. On the local scale, the effects of pollutants on some aspects of weather are unmistakable. The effects of man-made pollutants on global climate are a matter of debate, but they may already be significant.

Reactions of ozone and nitrogen oxides in power plant plumes

Abstract Results are presented of airborne measurements taken in the plumes of two coal and two gas-fired power plants. Measurements were made of the concentrations of NO, NO 2 , O 3 and SO 2 , temperature, relative humidity, and ultra-violet radiation. Ozone concentrations exceeding those of the surrounding ambient air were never found in these plumes, which were observed out to distances of 90 km (4 hours travel time) from the stacks. Analysis of the plume chemistry suggests that, over distances and time scales within which plumes are differentiable from background (the “near-field”), the chemistry is commonly controlled by the rates at which the plumes mix with the ambient air, rather than by chemical kinetics. Consequently, on those scales, the rates of conversion of NO to NO 2 are slow and the NO 2 /NO ratios are small (the highest ratio measured was 4.3). This analysis is consistent with the absence of observable ozone generation in the “near fields” of the power plant plumes studied.

The influence of a sulfur dioxide point source on the rain chemistry of a single storm in the Puget sound region

Sampling and chemical analysis of a rainstorm were undertaken to determine the influence of a large source of SO2 on regional precipitation chemistry. A definite correlation was obtained between hydrogen ion, sulfate ion and As concentration increases downwind of the source. Estimated sulfate deposition in a 1500 km2 downwind area was compared to existing models.

Stratospheric Ozone with Added Water Vapor: Influence of High-Altitude Aircraft

Simple, steady-state models for ozone photochemistry, radiative heat balance, and eddy-diffusive mass transport can be combined to estimate water-induced changes in the stratospheric ozone concentrations and temperatures, the integrated ozone column, the solar power transmitted to the earths surface, and the surface temperature. These changes have been computed parametrically for mixing fractions of water vapor between 3 x 10-6 and 6.5 x 10-6. With added water from the exhausts of projected fleets of stratospheric aircraft, the ozone column may diminish by 3.8 percent, the transmitted solar power increase by 0.07 percent, and the surface temperature rise by 0.04�K in the Northern Hemisphere. Due to a cancellation of terms, temperatures in the lower stratosphere remain essentially unchanged. These results are sensitive to the form of the water profile and emphasize the potential role of convective transients near 30 kilometers.

Evaporation of Ice in Space: Saturn's Rings

The photosputtering erosion velocity of ice in space is estimated to be 400 centimeters per billion years at 1 astronomical unit.

An analysis of the first year of MAP3S rain chemistry measurements

Abstract We have analysed rain chemistry measurements from the MAP3S program to derive numerical values of parameters for theoretical models of wet deposition of sulfur. These agree generally with values estimated earlier for Western Europe; the probability of rain is approximately equal to 0.12, the characteristic rainout rate about 0.3 h −1 , and the residence time for atmospheric sulfur species about 100 h. Both SO 4 2− and NO 3 − affect the pH at all stations. Factor analyses and meteorological analysis of selected high deposition events reveal inadequacies in present reporting and collecting procedures. From these we derive recommendations for future rain chemistry measurement programs.

Photoionization with Atomic Beams. II. Cadmium Atoms between 8.99 and 83 eV and Zinc Atoms between 27.35 and 65 eV

The energy dependences of the photoionization cross sections to produce Cd+, Cd2+, and Zn2+ have been measured with modulated atomic beams and pulsed, dispersed vacuum‐ultraviolet radiation. Results are presented for cadmium ions at energies between 8.99 and 83 eV and for zinc ions at energies between 27.35 and 65 eV.

Aqueous phase oxidation of sulfites by ozone in the presence of iron and manganese

Abstract The oxidation of sulfurIVspecies by ozone in aqueous solution was studied at 295 K, with pH between 4 and 6, pO3 between 0.3 and 2.0 ppm (v), SIV between 5 × 10−6 and 1 × 10−6 M, and Fe and Mn between 1 × 10−4and 5 × 10−6 M. Throughout this range the oxidation rates were simultaneously first order in SIV and pO3, and in the absence of added Fe or Mn displayed a rate coefficient equal to 0.12 + 0.02 mm−1 ppm (v)−1. With added Fe or Mn at concentrations above 10−5 M the rate coefficients each show maxima near to pH 4.5 of 0.27± 05 × 105M−1 min−1 ppm−1and 0.68 ±.08 × 105M−1 min−1 ppm−1. respectively. Near this pH the rates were first order with respect to concentrations of the metal ions. A phosphate citrate buffer system at 10−4 M slows the Fe catalyzed oxidation. No non-additive effect of simultaneous catalysis by Fe and Mn was observed.

Angular Distribution of Photoelectrons. I. Cadmium and Zinc Atoms at 584 and 1048 Å

The distribution of photoelectron trajectories has been measured with unpolarized resonance emission from helium and argon, modulated atomic beams of cadmium and zinc, a sector‐focusing photoelectron energy analyzer, and digital counting and demodulation techniques. The autoionizing transitions at 1048 A to produce Cd+2S1/2 and Zn+2S1/2 and the direct ionization at 584 A to produce Cd+2D5/2 all result in electron‐trajectory distributions which are close to cos2θ with respect to the electric vector of the radiation. Ionization at 584 A to produce Cd+2D3/2 results in an isotropic distribution. For cadmium the ratio of total cross sections to produce 2D5/2 / 2D3/2is 1.06 ± 0.07.