Abstract
The high time-resolution monitoring data are essential to estimate rapid changes in chemical compositions, concentrations, formation mechanisms, and likely sources of atmospheric particulate matter (PM). In this study, <TEX>$PM_{2.5}$</TEX> sulfate, <TEX>$PM_{2.5}$</TEX>, <TEX>$PM_{10}$</TEX>, and the number concentration of size-resolved PMs were monitored in Fukuoka, Japan by good time-resolved methods during the springtime. The highest monthly average <TEX>$PM_{2.5}$</TEX> sulfate was found in May (<TEX>$8.85{\mu}g\;m^{-3}$</TEX>), followed by April (<TEX>$8.36{\mu}g\;m^{-3}$</TEX>), March (<TEX>$8.13{\mu}g\;m^{-3}$</TEX>), and June (<TEX>$7.22{\mu}g\;m^{-3}$</TEX>). The cases exceed the Japanese central government's safety standard for <TEX>$PM_{2.5}$</TEX> (<TEX>$35{\mu}g\;m^{-3}$</TEX>) reached 10.11% during four months campaign. The fraction of <TEX>$PM_{2.5}$</TEX> sulfate to <TEX>$PM_{2.5}$</TEX> varied from 12.05% to 68.11% with average value of 35.49% throughout the entire period of monitoring. This high proportion of sulfate in <TEX>$PM_{2.5}$</TEX> is an obvious characteristic of the ambient <TEX>$PM_{2.5}$</TEX> in Fukuoka during the springtime. However, the average fraction of <TEX>$PM_{2.5}$</TEX> sulfate to <TEX>$PM_{2.5}$</TEX> in three rain events occurred during our intensive campaign fell right down to 15.53%. Unusually high <TEX>$PM_{2.5}$</TEX> sulfate (> <TEX>$30{\mu}g\;m^{-3}$</TEX>) marked on three days were probably affected by the air parcels coming from the Chinese continent, the natural sulfur in the remote marine atmosphere, and a large number of ships sailing on the nearby sea. The theoretical number concentration of <TEX>$(NH_4)_2SO_4$</TEX> in <TEX>$PM_{0.5-0.3}$</TEX> was originally calculated and then compared to <TEX>$PM_{2.5}$</TEX> sulfate. A close resemblance between the diurnal variations of the theoretically calculated number concentration of <TEX>$(NH_4)_2SO_4$</TEX> in <TEX>$PM_{0.5-0.3}$</TEX> and <TEX>$PM_{2.5}$</TEX> sulfate concentration indicates that the secondary formed <TEX>$(NH_4)</TEX><TEX>_2SO_4$</TEX> was the primary form of sulfate in <TEX>$PM_{2.5}$</TEX> during our monitoring period.
Highlights
As the primary gaseous pollutant, sulfur dioxide (SO2) with nitrogen oxides (NOx) is emitted from the burning processes of fossil fuels and can be oxidized in the atmosphere to form gas-phase sulfate via reaction with OH radical to yield H2SO4 (Mauldin et al, 2012)
We investigated the characteristics of the highly time-resolved PM2.5 sulfate measured sim ultaneously with PM2.5, PM10, and number concentration of size-resolved particulate matter (PM) in a Japanese urban site
PM2.5 sulfate has a strong relationship with the number concentration of PM0.5-0.3 (R = 0.90)
Summary
As the primary gaseous pollutant, sulfur dioxide (SO2) with nitrogen oxides (NOx) is emitted from the burning processes of fossil fuels and can be oxidized in the atmosphere to form gas-phase sulfate via reaction with OH radical to yield H2SO4 (Mauldin et al, 2012). The gas-phase sulfuric acid, preferentially form ammonium sulfate under most conditions, though ammonium nitrate is favored by low temperature and high humidity. In order to fully understand the health risk and other local/global effects of sulfate particle as well as to control the sources of direct PM2.5, its spatio-temporal distributions and transport with the patterns of source emissions must be comprehensively investigated. The availability of high time-resolved PM2.5 sulfate measurement provides the opportunity to better characterize and improve its exposure estimate. A good time-resolved monitoring for PM2.5 sulfate will provide us with valuable knowledge regarding its health effect as well as formation process, and transport. We investigated the characteristics of the highly time-resolved PM2.5 sulfate measured sim ultaneously with PM2.5, PM10, and number concentration of size-resolved PMs in a Japanese urban site
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