HR: 09:15h
AN: A51E-05    [Abstracts]
TI: Measurements of atmospheric mercury at Storm Peak Laboratory in the central Rocky Mountains: Evidence for local/ regional emissions and influence of long-range transport from Asia
AU: * Hallar, A G
EM: ghallar@dri.edu
AF: Desert Research Institute (DRI) Division of Atmospheric Sciences, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: * Hallar, A G
EM: ghallar@dri.edu
AF: DRI's Storm Peak Laboratory, P.O. Box 882530, Steamboat Springs, CO 80488, United States
AU: Obrist, D
EM: Daniel.Obrist@dri.edu
AF: Desert Research Institute (DRI) Division of Atmospheric Sciences, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: McCubbin, I B
EM: ian.mccubbin@dri.edu
AF: Desert Research Institute (DRI) Division of Atmospheric Sciences, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: McCubbin, I B
EM: ian.mccubbin@dri.edu
AF: DRI's Storm Peak Laboratory, P.O. Box 882530, Steamboat Springs, CO 80488, United States
AU: Rahn, T
EM: trahn@lanl.gov
AF: Los Alamos National Laboratory, Earth & Environmental Sciences Division, Los Alamos, NM 87545, United States
AB: The goal of this study was to test if Asian long-range transport (ALRT) of pollutants can be observed significantly inland in North America. Our point of observation is the Storm Peak Laboratory (SPL), a high-elevation mountaintop research facility (3200m asl) in the Rocky Mountains located 1500 km inland from the Pacific where near-coastal stations, such as Mt. Bachelor, have previously measured mercury enhancements due to ALRT. Measurements of gaseous elemental mercury (GEM) from October 2006 to May 2007 averaged 1.83 ± 0.15 ng m-3 with minimum and maximum concentrations of 1.28 ng m-3 and 2.61 ng m-3, respectively. GEM showed pronounced diurnal patterns with peak concentrations during daytime and lowest concentrations during late night/early morning hours. In fall and winter, the GEM patterns almost identically follow diurnal fluctuations of water vapor, aerosol concentration, and ozone. The daily fluctuations are due to daytime surface heating which causes the local boundary layer (BL) to move up to SPL during the day and contract downslope during the night, allowing for measurement of free tropospheric air. Thus, the daily GEM enhancements for the fall and winter seasons are likely due to local and regional sources of mercury to the BL from anthropogenic and natural emissions. In spring, diurnal patterns of GEM and carbon monoxide (CO) continue to exhibit diurnal patterns but concentration increases occurred time-shifted with respect to water vapor, aerosol, and ozone concentrations. This suggests that sources other than upward mixing of BL air contributed to the observed mercury during that time period. One very pronounced GEM enhancement occurred between March 31 and April 6, 2007. CO levels increased with GEM during the event. Calculated 10-day back-trajectories (Hysplit) indicate that air masses measured at SPL had a likely source area of Eastern Asia. Our data indicate that mercury loads from ALRT are not limited to the coastal areas but can be carried far inland and affect areas such as the Rocky Mountains.
UR: http://www.stormpeak.dri.edu
DE: 0322 Constituent sources and sinks
DE: 0341 Middle atmosphere: constituent transport and chemistry (3334)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting