Aerosol pH Research Articles

The Henry's law constant of trifluoroacetic acid and its partitioning into liquid water in the atmosphere

Abstract The Henry's law constant of trifluoroacetic acid [K H′ (mol kg −1 atm −1 ), for the equilibrium CF 3 COOH (g) ⇔ CF 3 000H (aq) ] has been determined from measured partial pressure over aqueous solutions at 278.15, 298.15 and 308.15 K, and is given by: ln(K H′ ) = 9.099 − 9.328 × 10 3 (1/T r − 1/T) where T (K) is temperature and T r is equal to 298.15 K. Accuracy is estimated to be ±25% in K H′ , partly limited by uncertainties in the pK a of the acid (0.47 at all temperatures, from literature data). Trifluoroacetic acid in the atmosphere will partition entirely into fog and cloud water (0.05–1.0 g H 2 O m −3 ), but can reside in both phases for the liquid water contents typical of aerosols (10 −5 − 10 −4 g H 2 O m t3 ) depending on aerosol pH and to some extent on composition.

The Henry's law constant of trifluoroacetic acid and its partitioning into liquid water in the atmosphere

The Henry's law constant of trifluoroacetic acid [K H′ (mol kg −1 atm −1), for the equilibrium CF 3COOH (g) ⇔ CF 3000H (aq)] has been determined from measured partial pressure over aqueous solutions at 278.15, 298.15 and 308.15 K, and is given by: ln(K H′) = 9.099 − 9.328 × 10 3(1/T r − 1/T) where T (K) is temperature and T r is equal to 298.15 K. Accuracy is estimated to be ±25% in K H′, partly limited by uncertainties in the pK a of the acid (0.47 at all temperatures, from literature data). Trifluoroacetic acid in the atmosphere will partition entirely into fog and cloud water (0.05–1.0 g H 2O m −3), but can reside in both phases for the liquid water contents typical of aerosols (10 −5 − 10 −4 g H 2O m t3) depending on aerosol pH and to some extent on composition.

Mechanism of induction of asthmatic attacks initiated by the inhalation of particles generated by airbag system deployment.

We have previously demonstrated that inhalation of the dust produced by dual frontal airbag deployment can result in significant bronchospasm in approximately 40% of mild to moderate asthmatics. This study was performed to determine the cause of the asthmatic response. Controlled laboratory study. Asthmatics who were previously tested for their response to airbag effluents were exposed for twenty minutes to either 1) airbag effluents from airbag systems in which the airbag was insulated from the hot deployment module; 2) non-sulfur containing airbag effluents; 3) sodium chloride aerosol; or 4) sodium carbonate-bicarbonate aerosol (pH 10). Pre-exposure, post-exposure, and 2 hour post exposure pulmonary spirometry and mechanics were measured. Subject's filled out symptoms questionnaires before exposure, 2, 4, 8, 12, and 19 minutes into the exposure, immediately post-exposure, and 2 hours post-exposure. Prevention of the pyrolysis of the passenger-side bag as it rested on the hot module after deployment did not diminish the asthmatic response. Removal of sulfur-containing oxidants from the airbag pyrotechnic chemistry, which may have led to sulfite production, similarly did not alleviate the asthmatic response to the airbag effluents. Lastly, when asthmatics were exposed to sodium chloride and sodium carbonate-bicarbonate aerosols at approximately the same concentration (approximately 220 mg/m3) as the airbag aerosol concentration that occurred in the in-car tests, they had responses similar to those produced by the airbag exposures. We conclude that the amount of soluble particulate contained in the aerosol discharged into the passenger compartment by dual frontal airbag deployment is largely the cause of the observed evoked asthmatic attacks. The alkaline pH of the airbag and carbonate aerosols may have added an additional degree of provocation.

Scanning Electron-Microscope Analysis of Aerosols in Snow and ice Cores from Greenland (Abstract)

In previous work, particle analyses of fresh snow and ice cores from Camp Century, Greenland, were conducted by transmission electron-microscopy. The particles found most frequently were silicate minerals 0.05-8 μm diameter (Kumai 1977). The mean pH of snow in Ellesmere Island (81 °N, 73°W) was 5.23 for 1954-80 (Koerner and Fisher 1982). The mean pH of snow in Hanover, NH, was 4.61 for 1972-73 and 4.48 for 1980-83. The mean pH of snow in a rural area near Fairbanks, Alaska, was 5.60 for 1972-73 (Kumai 1985). In this paper, the results of measurement of pH, electrolytic conductivity, aerosol concentration and elemental analysis of aerosols in snow and ice cores from Greenland are described and compared with those of snow from Alaska, the Canadian Arctic and New Hampshire. The snow samples were collected at Dye 3, Greenland, from 17 to 250 cm depth; they were deposited during snowfalls from January 1980 to spring 1983. A total of 45 snow samples was examined; the samples were each about 65 g and collected at 5 cm intervals in the snow pit. The snow and ice-core samples were melted in a microwave oven for measurements of pH and electrolytic conductivity. A pH meter (Solution Analyzer, model 4505A) was calibrated by two buffer solutions of pH 4.00 and 7.00 at 25 °C. Two instruments were used for electrolytic conductivity measurements, Solution Analyzer, model 4505A, and Conductance Bridge RCM 1581, and calibrated by a standard solution of 0.005 N KC1 (720 ± 1 (μS cm−1) at 25°C. The snow and ice melt-water samples were filtered through polycarbonate membrane filters of 0.4 μm pore diameter. Particles remaining on the filters dried in a vacuum oven at 30°C, and the aerosol concentrations measured by chemical balance. The aerosols on the filters were coated by Au and Pd vapor in a vacuum chamber, for examination by scanning electron-microscopy and energy-dispersive X-ray analysis. Results of melted snow measurements from Greenland were as follows. The pH ranged from 4.57 to 5.01; the mean pH was 4.81 in 1981. For 1982 the pH ranged from 4.72 to 4.93; the mean was 4.81. For 1983, the pH ranged from 4.50 to 5.20; the mean was 4.85. The mean pH of all snow from Greenland was lower than that of snow in a rural area of the Alaskan and Canadian Arctic, but higher than that of snow in New Hampshire. Electrolytic conductivity of snow from Greenland varied from 3.95 to 9.70 μS cm−1 for 1981, and the mean was 6.20 μS cm−1. In 1982 it ranged from 3.21 to 8.53 μS cm−1; the mean was 5.12 μS cm−1. For 1983, it ranged from 3.40 to 6.19 μS cm−1; the mean was 4.95 μS cm1. The mean electrolytic conductivity of snow from Greenland was much lower than that of snow in Hanover, New Hampshire. Concentrations of particulate matter in snow from Greenland ranged from 0.24 to 2.40 mg kg−1; the mean was 1.37 mg kg−1. The particulate matter was examined by scanning electron-microscopy. Several kinds of silicate minerals, spherules and unidentified organic particles were found. Spherules found in the snow samples are glass, Fe-, Ti- and Ca-rich, and considered to be fly-ash particles from coal combustion.

Scanning Electron-Microscope Analysis of Aerosols in Snow and ice Cores from Greenland (Abstract)

In previous work, particle analyses of fresh snow and ice cores from Camp Century, Greenland, were conducted by transmission electron-microscopy. The particles found most frequently were silicate minerals 0.05-8 μm diameter (Kumai 1977). The mean pH of snow in Ellesmere Island (81 °N, 73°W) was 5.23 for 1954-80 (Koerner and Fisher 1982). The mean pH of snow in Hanover, NH, was 4.61 for 1972-73 and 4.48 for 1980-83. The mean pH of snow in a rural area near Fairbanks, Alaska, was 5.60 for 1972-73 (Kumai 1985).In this paper, the results of measurement of pH, electrolytic conductivity, aerosol concentration and elemental analysis of aerosols in snow and ice cores from Greenland are described and compared with those of snow from Alaska, the Canadian Arctic and New Hampshire.The snow samples were collected at Dye 3, Greenland, from 17 to 250 cm depth; they were deposited during snowfalls from January 1980 to spring 1983. A total of 45 snow samples was examined; the samples were each about 65 g and collected at 5 cm intervals in the snow pit. The snow and ice-core samples were melted in a microwave oven for measurements of pH and electrolytic conductivity. A pH meter (Solution Analyzer, model 4505A) was calibrated by two buffer solutions of pH 4.00 and 7.00 at 25 °C. Two instruments were used for electrolytic conductivity measurements, Solution Analyzer, model 4505A, and Conductance Bridge RCM 1581, and calibrated by a standard solution of 0.005 N KC1 (720 ± 1 (μS cm−1) at 25°C. The snow and ice melt-water samples were filtered through polycarbonate membrane filters of 0.4 μm pore diameter. Particles remaining on the filters dried in a vacuum oven at 30°C, and the aerosol concentrations measured by chemical balance. The aerosols on the filters were coated by Au and Pd vapor in a vacuum chamber, for examination by scanning electron-microscopy and energy-dispersive X-ray analysis.Results of melted snow measurements from Greenland were as follows. The pH ranged from 4.57 to 5.01; the mean pH was 4.81 in 1981. For 1982 the pH ranged from 4.72 to 4.93; the mean was 4.81. For 1983, the pH ranged from 4.50 to 5.20; the mean was 4.85. The mean pH of all snow from Greenland was lower than that of snow in a rural area of the Alaskan and Canadian Arctic, but higher than that of snow in New Hampshire.Electrolytic conductivity of snow from Greenland varied from 3.95 to 9.70 μS cm−1 for 1981, and the mean was 6.20 μS cm−1. In 1982 it ranged from 3.21 to 8.53 μS cm−1; the mean was 5.12 μS cm−1. For 1983, it ranged from 3.40 to 6.19 μS cm−1; the mean was 4.95 μS cm1. The mean electrolytic conductivity of snow from Greenland was much lower than that of snow in Hanover, New Hampshire.Concentrations of particulate matter in snow from Greenland ranged from 0.24 to 2.40 mg kg−1; the mean was 1.37 mg kg−1. The particulate matter was examined by scanning electron-microscopy. Several kinds of silicate minerals, spherules and unidentified organic particles were found. Spherules found in the snow samples are glass, Fe-, Ti- and Ca-rich, and considered to be fly-ash particles from coal combustion.

Acid rain: Effects on arachidonic acid metabolism in perfused and ventilated guinea-pig lung

Isolated, perfused and ventilated guinea-pig lungs were exposed for 10 min to acid (sulphuric + nitric acid) aerosol mimicking acid rain at pH 4.5 or 2.5, as well as to a control distilled water aerosol (pH 6.0–6.5). Lung perfusing solution was recovered and thromboxane (TX) B 2 and leukotriene (LT) B 4 were measured by radioimmunoassay (RIA) techniques. In a series of experiments TXB 2 release averaged 0.43 ± 0.18 (± SD) ng/min during exposure to distilled water aerosol and increased to 0.70 ± 0.30 ng/min during exposure to acid aerosol at pH 4.5 ( P < 0.05). In a second series of experiments TXB 2 release was 0.46 ± 0.18 ng/min and increased to 1.07 ± 0.51 ng/min ( P < 0.01) after acid aerosol at pH 2.5. In both cases LTB 4 release, reflecting lipoxygenase activity, was unchanged. LTC 4 levels were not measurable under basal conditions as well as after exposure to acid aerosol. A pneumoconstriction was also observed, being more pronounced after acid aerosol at pH 2.5. Individual sulphuric and nitric acid aerosol component solutions at pH 2.5 evoked TXB 2 and airway resistance changes corresponding to those observed with the mixed acid aerosol. LTB 4 was not modified. Acid rain inhalation may directly stimulate pathways leading to the bronchoconstrictor and pro-aggregating TXA 2 synthesis in isolated guinea-pig lung, without affecting the lipoxygenase pathway of arachidonic acid metabolism.

Aerosol deposition in the human respiratory tract

Rising sulfur dioxide emissions from increased coal combustion present risks, not only of acid rain, but also to health by inhalation of the SO 2 and acid to the lung. We are investigating human inhalation of ppm SO 2 concentrations mixed with aerosol of submicrometer aqueous salt droplets to determine the effects on lung function and body chemistry. Unlike some investigators, we emphasize ammonium sulfate and trace element aerosol composition which simulates ambient air; aerosol pH, relative humidity, and temperature control to reveal gas-particle reaction mechanisms; and dose estimates from length of exposure, SO 2 concentration, and a direct measurement of respiratory deposition of aerosol as a function of particle size by cascade impactor sampling and elemental analysis by PIXE. Exposures, at rest or during exercise, are in a walk-in chamber at body temperature and high humidity to simulate Florida's summer climate. Lung function measurement by spirometry is carried out immediately after exposure. The results are significant in relating air quality to athletic performance and to public health in the southeastern United States.