Size mass distribution of water-soluble ionic species and gas conversion to sulfate and nitrate in particulate matter in southern Taiwan

Water-soluble ions such as sulfate may have great impacts on atmospheric pollution. To determine the deposition effect of PM 2.5 sulfates, the major PM 2.5 constituents, in the forest canopy in Beijing, China, an investigation was carried out in an urban forest, Olympic Forest Park, and a suburban forest, Jiufeng National Forest Park. We measured the vertical distributions of sulfate by using monitoring towers in the two forests at the same times in March and May 2013. Sulfate (SO 4 2− )was predominant in all PM 2.5 water-soluble inorganic ions, with a proportion >40%. The vertical concentration of SO 4 2− increased with height, and the average sulfate concentration in Olympic ForestPark was higher than that in Jiufeng National Forest Park. Results also revealed that meteorological conditions had significant impacts on both the sulfate concentration and the deposition velocity. In winter, the deposition of SO 4 2− through the canopy was not obvious in the two forest parks, which was quite the opposite in spring. The deposition velocity in the daytime was higher than that in the nighttime in both Olympic Forest Park (0.9 ± 1.0 cm/s vs. 0.4 ± 0.3 cm/s) and Jiufeng National Forest Park (1.3 ± 1.2 cm/s vs. 0.8 ± 0.8 cm/s). While Jiufeng National Forest Park turned out to have a higher average sulfate deposition velocity than Olympic Forest Park.

Section: Introductionmentioning

confidence: 99%

Deposition of PM2.5 Sulfate in the Spring on Urban Forests in Beijing, China

Zhao

Lun

et al. 2017

Atmosphere

“…There are distinct annual cycles to the primary pollutants (Fig. 2 ( a , c , e , g )), higher values occurring each winter (Lee et al 2018 ; Tsai et al 2013 ); seasonal cycles 2000–2020 appear as insets. Trends across this period suggest continuous improvement to the primary pollutants such as NO x and PM 10 ( τ =−0.40, p <.0001 and τ =−0.23, p <.0001), and notably for SO 2 ( τ =−0.62, p <.000).…”

Section: Resultsmentioning

confidence: 98%

Fifty-year change in air pollution in Kaohsiung, Taiwan

Brimblecombe

2022

Environ Sci Pollut Res

The change in air quality in cities can be the product of regulation and emissions. Regulations require enforcement of emission reduction, but it is often shifting economic and societal structures that influence pollutant emissions. This study examines the long-term record of air pollutants in Kaohsiung, where post-war industrialisation increased pollution substantially, although improvements are observed in recent decades as the city moved to a more mixed economy. The study tracks both gases and particles across a period of significant change in pollution sources in the city. Concentrations of SO2 and aerosol SO42− were especially high ~1970, but these gradually declined, although SO42− to a lesser extent than its precursor, SO2. While twenty-first century emissions of SO2 and NOx have declined, this has been less so for NH3, because it arises from predominantly agricultural sources. The atmosphere in Kaohsiung continues to have high concentrations of O3, and these have risen in the city, likely a product of less titration by NO. The changes have meant that ozone has become an increasing threat to health and agriculture. Despite a potential for producing (NH4)2SO4 and NH4NO3 aerosols, a product of a relatively constant supply of NH3, visibility has improved in recent years. Emissions of SO2 and NOx should continue to be reduced, as these strongly affect the amount of fine secondary aerosol. However, the key problem may be ozone, which is difficult to control as it requires careful consideration of the balance of NOx and hydrocarbons so important to its production.

“…There are distinct annual cycles to the primary pollutants (Fig. 2a,c,e,g), higher values occurring each winter Tsai et al, 2013); seasonal cycles 2000-2020 appear as insets. The trends suggest continuous improvement to the primary pollutants, and often, though most notably for SO 2 , low values are evident at the Meinong rural site (Fig.…”

Section: Decadal Change In Primary Pollutantsmentioning

confidence: 97%

Fifty-Year Change in Air Pollution in Kaohsiung, Taiwan

Brimblecombe

2022

Preprint

The change in air quality in cities can be the product of regulation and emissions. Regulations require enforcement of emission reduction, but it is often a shifting economic and societal structures that influence pollutant emissions. This study examines the long-term record of air pollutants in Kaohsiung, where post-war industrialisation increased pollution dramatically, although improvements are observed in recent decades as the city moved to a more mixed economy. The study tracks both gases and particles across a period of significant change in pollution sources in the city. Concentrations of SO2 and aerosol SO42- were especially high ~1970, but these gradually declined, although the SO42- to a lesser extent than its precursor, SO2. While 21st century emissions of SO2 and NOx have declined, this has been less so for NH3, because it arises from predominantly agricultural sources. The atmosphere in Kaohsiung continues to have high concentrations of O3, and these have risen in the city, likely a product of less titration by NO. The changes have meant that ozone has become an increasing threat to health and agriculture. Despite a potential for the production of (NH4)2SO4 and NH4NO3 aerosols, a product of a relatively constant supply of NH3, visibility has improved in recent years. The emissions of SO2 and NOx should continue to be reduced, as these strongly affect the amount of fine secondary aerosol. However, the key problem may be ozone, which is difficult to control as it needs careful consideration of the balance of NOx and hydrocarbons so important to its production.