Electron microscopy of natural aerosols and the identification of particulate ammonium sulphate

Heard, M.J.; Wiffen, R.D.

doi:10.1016/0004-6981(69)90106-1

Cited by 71 publications

(17 citation statements)

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“…13 None resembled pure sulfuric acid particles, which possess a characteristic form: a central droplet surrounded by a large number of much smaller satellites. 14 We cannot exclude the possibility of some neutralization by ambient ammonia occurring after sampling. (d) The rest (about 5 percent) are solid particles that do not decompose under the TEM beam.…”

Section: Sulfatesmentioning

confidence: 99%

Characteristics of Individual Particles at a Rural Site in the Eastern United States

Mamane

Dzubay

1986

Journal of the Air Pollution Control Association

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Section: Sulfatesmentioning

confidence: 99%

Characteristics of Individual Particles at a Rural Site in the Eastern United States

Mamane

Dzubay

1986

Journal of the Air Pollution Control Association

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“…D 'Ans, 1913), and observations of ammonium, sulphate, and nitrate in PM have appeared in the literature over the past sixty years (cf. Robbins and Cadle, 1958;Fenn et al, 1963;Spurny and Heard, 1969;Heard and Wiffen, 1969;Gordon and Bryan, 1973;Anlauf et al, 1978;Brosset, 1978;Stelson et al, 1979;Tanner, 1983). The partitioning between different phases, including gases, may be predicted using fundamental thermodynamics theory (cf.…”

Section: Introductionmentioning

confidence: 99%

Modelling the impacts of ammonia emissions reductions on North American air quality

et al. 2009

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Abstract.A unified regional air-quality modelling system (AURAMS) was used to investigate the effects of reductions in ammonia emissions on regional air quality, with a focus on particulate-matter formation. Three simulations of one-year duration were performed for a North American domain: (1) a base-case simulation using 2002 Canadian and US national emissions inventories augmented by a more detailed Canadian emissions inventory for agricultural ammonia; (2) a 30% North-American-wide reduction in agricultural ammonia emissions; and (3) a 50% reduction in Canadian beef-cattle ammonia emissions. The simulations show that a 30% continent-wide reduction in agricultural ammonia emissions lead to reductions in median hourly PM 2.5 mass of <1 µg m −3 on an annual basis. The atmospheric response to these emission reductions displays marked seasonal variations, and on even shorter time scales, the impacts of the emissions reductions are highly episodic: 95th-percentile hourly PM 2.5 mass decreases can be up to a factor of six larger than the median values.A key finding of the modelling work is the linkage between gas and aqueous chemistry and transport; reductions in ammonia emissions affect gaseous ammonia concentrations close to the emissions site, but substantial impacts on particulate matter and atmospheric deposition often occur at considerable distances downwind, with particle nitrate being the main vector of ammonia/um transport. Ammonia emissions reductions therefore have trans-boundary consequences downwind. Calculations of critical-load exceedances for sensitive ecosystems in Canada suggest that ammonia emission reductions will have a minimal impact on Correspondence to: P. A. Makar (paul.makar@ec.gc.ca) current ecosystem acidification within Canada, but may have a substantial impact on future ecosystem acidification. The 50% Canadian beef-cattle ammonia emissions reduction scenario was used to examine model sensitivity to uncertainties in the new Canadian agricultural ammonia emissions inventory, and the simulation results suggest that further work is needed to improve the emissions inventory for this particular sector. It should be noted that the model in its current form neglects coarse mode base cation chemistry, so the predicted effects of ammonia emissions reductions shown here should be considered upper limits.

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“…The arrows represent the ranges of uncertainty for the respective mode in each size distribution based on results from sizing of PSL spheres for SEM data, and 5 % uncertainty for TDMPS measurements (Wiedensohler et al, 2012). (Heard and Wiffen, 1969;Fig. 12).…”

Section: The Approach Applied To Two Aerosol Samples Collected Duringmentioning

confidence: 99%

A method for sizing submicrometer particles in air collected on Formvar films and imaged by scanning electron microscope

2013

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Abstract.A method was developed to systematically investigate individual aerosol particles collected onto a polyvinyl formal (Formvar)-coated copper grid with scanning electron microscopy. At very mild conditions with a low accelerating voltage of 2 kV and Gentle Beam mode aerosol particles down to 20 nm in diameter can be observed. Subsequent processing of the images with digital image analysis provides size resolved and morphological information (elongation, circularity) on the aerosol particle population. Polystyrene nanospheres in the expected size range of the ambient aerosol particles (20-900 nm in diameter) were used to confirm the accuracy of sizing and determination of morphological parameters. The relative standard deviation of the diameters of the spheres was better than ±10 % for sizes larger than 40 nm and ±18 % for 21 nm particles compared to the manufacturer's certificate.Atmospheric particles were collected during an icebreaker expedition to the high Arctic (north of 80 • ) in the summer of 2008. Two samples collected during two different meteorological regimes were analyzed. Their size distributions were compared with simultaneously collected size distributions from a Twin Differential Mobility Particle Sizer, which confirmed that a representative fraction of the aerosol particles was imaged under the electron microscope. The size distributions obtained by scanning electron microscopy showed good agreement with the Twin Differential Mobility Sizer in the Aitken mode, whereas in the accumulation mode the size determination was critically dependent on the contrast of the aerosol with the Formvar-coated copper grid. The morphological properties (elongation, circularity) changed with the number of days the air masses spent over the pack-ice area north of 80 • before the aerosol particles were collected at the position of the icebreaker and are thus an appropriate measure to characterize transformation processes of ambient aerosol particles.

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Electron microscopy of natural aerosols and the identification of particulate ammonium sulphate

Cited by 71 publications

References 1 publication

Characteristics of Individual Particles at a Rural Site in the Eastern United States

Characteristics of Individual Particles at a Rural Site in the Eastern United States

Modelling the impacts of ammonia emissions reductions on North American air quality

A method for sizing submicrometer particles in air collected on Formvar films and imaged by scanning electron microscope

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