Seasonal properties on PM1 and PGEs (Rh, Pd, and Pt) in PM1

Özet

Vehicle exhaust converters (VECs) are considered the sources of platinum group element (PGEs) to environment, but PGEs emitted from coal combustion in heating period in winter are ignored by researchers. Snow affecting on PM1 and PGEs in PM1 are given little attention either. A detailed examination of the concentrations of PM1 and its platinum group element (PGEs) components in Changji (Xinjiang, Northwest in China) has revealed their seasonal variations and influencing mechanisms. Each sample was continuously collected for 24 h using a medium flow rate intelligent total suspended particulate (TSP) sampler, then digested via an HNO3-HCl-HF system and analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). The mean concentration of PM1 was 0.10 (0.04–0.41) mg m−3, and the concentrations of Rh, Pd and Pt in PM1 were 0.06 (n.d.–0.21) ng m−3, 1.99 (n.d.–10.77) ng m−3, and 0.05 (n.d.–0.19) ng m−3, respectively. Among the PGEs components, Pd had the highest concentration, while the concentrations of Pt and Rh were low. PM1 in winter is two or three times comparison than the other seasons, due to its major emission from coal combustion during the heating period. But the Rh, Pd, and Pt concentrations were lower in winter than in the other seasons. Rh, Pd, and Pt also had similar seasonal variations, their variation was different from the variation of PM1, and this different variation is attributed to the strongly scavenging effect of snow. The PGEs emissions from coal combustion were incline to enriched in large particles with a high degree of selectivity and the content of PGEs in PM1 was not strongly influenced by coal combustion. Therefore seasonal variations of TSP, PM2.5, and PGEs in PM1 were obviously different. The common source of PGEs in PM1 is vehicle exhaust converters (VECs), but VECs were not the sole source of Pt, which was also rarely emitted from coal combustion.