Application of the Passive Sampler Developed for Atmospheric Mercury and Its Limitation

Abstract

In this study, a passive sampler for gaseous elemental mercury (GEM) was developed and applied to field monitoring. Three Radiello® diffusive bodies with gold-coated beads as Hg adsorbent were installed in an acrylic external shield. Hg uptake mass linearly increased as the deployment time increased until 8 weeks with an average gaseous Hg concentration of 2 ng m−3. The average of the experimental sampling rate (SR) was 0.083 m3 day−1 and showed a good correlation with theoretical SRs, indicating that a major adsorption mechanism was molecular diffusion. Nonetheless, the experimental SR was approximately 33% lower than the modeled SR, which could be associated with inefficient uptake of GEM in the sampler or uncertainty in constraining model parameters. It was shown that the experimental SR was statistically affected by temperature and wind speed but the calibration equation for the SR by meteorological variables should be obtained with a wider range of variables in further investigation. When the uptake rates were compared to the active Hg measurements, the correlation was not significant because the passive sampler was not sufficiently adept at detecting a small difference in the GEM concentration of from 1.8 to 2.0 ng m−3. However, the results for spatial Hg concentrations measured near cement plants in Korea suggest a possible application in field monitoring. Future research is needed to fully employ the developed passive sampler in quantitative assessment of Hg concentrations.

Keywords

• gaseous elemental mercury
• passive sampler
• gold-coated beads
• sampling rate
• spatial variation