Chemical characterization, source apportionment, and health risk assessment nexus of PM2.5-bound major heavy metals in Bien Hoa city, southern Vietnam

Abstract

Bien Hoa, a city in Dong Nai province of Vietnam, is a populous area and a hotspot for industrial establishments. Dioxins, as residue from the U.S. - Vietnam war, are also a major concern to the city. Remedy of contaminated soil is being conducted in the area. With said situation, it raises the question of the overall air quality in Bien Hoa city. Thus, our research group conducted this work to fill the knowledge gap. The methodology involves the collection of 40 samples of PM2.5, at two sites (urban and industrial zone), from both the rainy (Oct. 15, 2021–Oct. 25, 2021) and the dry (Mar. 15, 2022–Mar. 25, 2022) seasons, to assess the concentration of eleven (11) heavy metals (As, Pb, Mn, Fe, Cd, Cr, Zn, Co, Al, Cu, and Ni). The analysis is performed using an ICP-MS iCAP RQ. The result shows that the concentration of PM2.5 in the dry season is higher (at 80 μg/m3), potentially due to increased moisture content and wet scrubbing, in the rainy season (28.3 μg/m3). The trace of Zn is the most abundant in PM2.5-bond from both seasons. It is caused by the contribution of emissions from road-traffic activities, namely vehicular exhaust, tyre abrasion and degradation of lubricates. The contribution of industrial processes, such as combustion, metallurgical production, biomass incineration and waste treatment also plays a role in high Zn concentration. Out of eleven, six heavy metals (including Pb, As, Cr, Cu, Zn và Cd) have enrichment factor values over 100. Health risk assessment shows that the total cancer risk (TCR) values are all within 10−4 ≤ TCR ≤10−3, which indicates a moderate cancer risk from respiratory exposure in the city.

Keywords

• PM2.5
• Heavy metals
• Enrichment factor
• Cancer risk assessment
• Source apportionment