Characteristics of Elemental and Organic Carbon in Atmospheric Nanoparticles at Different Sampling Locations in Vietnam

Abstract

Atmospheric ultrafine particles (NPs or PM0.1) were investigated at a roadside of Nguyen Van Cu road (Vinacomin) and at a mixed site in the Hanoi University of Science and Technology (HUST) in Hanoi, Vietnam. The sampling was conducted during a rainy reason and a dry season to determine the characteristics of atmospheric elemental and organic carbon in the nanoparticles. The relative contributions of organic carbon (OC) and elemental carbon (EC) to total carbon (TC) at HUST were 83.7 – 85.0% and 15.0–16.3 %, respectively; whereas those at Vinacomin’s sampling site accounted for 78.6 – 81.5% and 18.5 – 21.4 %, respectively. The study provides an interesting observation that particulate OC and EC have spatial and temporal variations dependent on sampling sites and weather conditions. In contrast, consistent OC/EC ratios were also found at both seasons of each location, in which the ratios were from 3.68 to 5.68. The correlations of OC and EC were found in the rainy season with the slopes ranging from 0.21–0.34; however, these correlations were not observed in the dry season. The relationships between OC and EC, char – EC and soot – EC can be used in primarily determining the sources of NPs in the atmosphere.

Size Distribution and Contribution of Particles From Rice Straw Open Burning to the Atmosphere in Hanoi

“…The concentration of nanoparticles at QO_RS burning site was 11.5 ± 3.9 μg/m 3 . Despite its low mass concentration, nanoparticles have been recognized to be more important and harmful than the larger size particles such as PM 2.5 at the same mass concentration [20,21]. Considering the mass concentration of fine particles, the mass concentration of PM 2.5 was 79.7 ± 46.5 μg/m 3 and 90.8 ± 33.2 μg/m 3 at DA_RS burning site and QO_RS burning site, respectively.…”

“…Numerous studies on size distribution and mass concentration of particles in the atmosphere have been conducted [12 -18]. In Viet Nam, several studies focused on mass concentration of nanoparticles and fine particles, carbonaceous components of nanoparticles at urban locations in Ha Noi [19,20]. Tran et al [21] assess the air quality in school environment in Ha Noi focus on the mass-size distribution and found that ultrafine particles accounted for around 15 -20 % wt/wt while fine particles (PM 2.5 ) made up almost 80 % wt/wt of PM 10 .…”