This research was initiated to characterize atmospheric deposition of reactive gaseous mercury (RGM), particulate mercury (HgP; <2.5 ??m), and gaseous elemental mercury (Hg0) in the arid lands of south central New Mexico. Two methods were field-tested to estimate dry deposition of three mercury species. A manual speciation sampling train consisting of a KCl-coated denuder, 2.5 ??m quartz fiber filters, and gold-coated quartz traps and an ion-exchange membrane (as a passive surrogate surface) were deployed concurrently over 24-h intervals for an entire year. The mean 24-h atmospheric concentration for RGM was 6.8 pg m-3 with an estimated deposition of 0.10 ng m-2 h-1. The estimated deposition of mercury to the passive surrogate surface was much greater (4.0 ng m-2 h -1) but demonstrated a diurnal pattern with elevated deposition from late afternoon to late evening (1400-2200; 8.0 ng m-2 h-1) and lowest deposition during the night just prior to sunrise (2200-0600; 1.7 ng m-2 h-1). The mean 24-h atmospheric concentrations for HgP and Hg0 were 1.52 pg m-3 and 1.59 ng m-3, respectively. Diurnal patterns were observed for RGM with atmospheric levels lowest during the night prior to sunrise (3.8 pg m-3) and greater during the afternoon and early evening (8.9 pg m-3). Discernible diurnal patterns were not observed for either HgP or Hg0. The total dry deposition of Hg was 5.9 ??g m-2 year-1 with the contribution from the three species as follows: RGM (0.88 ??g m-2 year-1), HgP (0.025 ??g m-2 year-1), and Hg0 (5.0 ??g m-2 year-1). The annual wet deposition for total mercury throughout the same collection duration was 4.2 ??g m-2 year-1, resulting in an estimated total deposition of 10.1 ??g m-2 year-1 for Hg. On one sampling date, enhanced HgP (12 pg m-3) was observed due to emissions from a wildfire approximately 250 km to the east. ?? 2006 American Chemical Society.
Additional publication details
Concentration and dry deposition of mercury species in Arid South Central New Mexico (2001-2002)