Metallic elements emitted from industrial sources in Taiwan: Implications for source identification using airborne PM

Abstract

Filterable stack total suspended particle (TSP) samples emitted from electric arc furnace (EAF) steel manufacturing plants, coal-fired power plants (CPP), cement mills (CM), and petroleum refineries (PR), were isokinetically collected using an in-stack PM device and analyzed for thirty-one targeted elements. The results showed that metallic elements constituted a majority (43–61%) of stack TSP mass in EAF steel plants and CM whereas contributed to a less fraction (11–27%) in CPP and PR. The coefficient of divergence (COD) values varied from 0.58 to 0.81, indicating that the elemental profiles between each industrial source were very distinct. Geological elements such as Al, Fe, Ca, Na, Mg, and K were the dominant elements in all industrial sources (50–96% of elemental mass). Besides, Zn was another dominant metal (22–40% of element mass) in addition to Fe in EAF steel plants and Ni (~3.6%) was the most predominant metal in oil-refinery. Tracers in different industrial sectors were also identified by source marker calculations. Moreover, the ratios of La/Ce (1.8) and La/Nd (6.0) in fluidized bed catalytic cracking (FCC) were 20–30 times higher than those of other industrial sectors. Utilizing both La/Ce and La/Nd ratios, the contribution of FCC PR to ambient primary TSP surrounding by the petroleum refinery was estimated to be 0.6%, which was comparable to the Taiwan Emission Data (0.7%). This highlighted that La/Ce and La/Nd ratios can be able to track the influence of petroleum refining sources on airborne particles in an industrial urban area in Taiwan.