Measure and modeling the ambient air particles and particle bound mercury Hg(p) at a traffic sampling site

Abstract

Ambient air samples were collected between Dec 9, 2008 and Jan 14, 2009 at a highway traffic site located in Sha-Lu, central Taiwan. Atmospheric particulates and particulate bound mercury Hg(p) dry deposition fluxes, concentrations and dry deposition velocities were also studied. The objective of this study was to: 1) measure the dry deposition concentrations of ambient air particles and particle bound mercury Hg(p) following one and two days of sampling events using the total suspended particulates (TSP) sampler, and dry deposition plate (DDP); 2) modeling the dry deposition fluxes of particles and particle bound mercury Hg(p) with calculated deposition velocities then to obtain a calculated dry deposition fluxes; and 3) compared the results of calculated dry deposition fluxes to measured dry deposition fluxes. All the results were presented with one and two days of sampling events with different deposition collection media (i.e., quartz filter and overhead projection film). The results indicated that the average calculated/measured dry deposition fluxes ratios for bound mercury (Hg(p)) for 24 sampling group were 2.27. The results also indicated that the one day calculated/measured dry deposition flux ratios for Hg(p) for overhead projection film and quartz filter were 2.62 and 1.92, respectively. In addition, the results indicated that the average calculated/measured dry deposition fluxes ratios for 24 sampling group were 4.03. The results also indicated that the two days of calculated/measured dry deposition flux ratios for Hg(p) for overhead projection film and quartz filter were 4.64 and 3.42, respectively. The results of particle bound mercury Hg(p) calculated dry deposition model are slightly higher than that of measured dry deposition flux in either one day or two days of sampling period for both of overhead projection and quartz filter collection medium. .Though there are no significant differences of mean values for both particulates and Hg(p) using overhead projection film or quartz filter as a collection media for the dry deposition-study (Fang et al., 2009), quartz filter exhibits better calculated/measured ratio in the prediction of particle bound mercury (Hg(p)) than that of overhead projection film for either one day of the two days of sampling periods.