A new article by David Reidmiller recently published in Atmospheric Chemistry and Physics (Vol. 9, p. 5027-5042) incorporates observations from EPA’s CASTNet sites and results from 16 global chemical transport models as part of the Hemispheric Transport of Air Pollution (www.htap.org) project. Each model conducted an array of sensitivity simulations in which anthropogenic O3 precursor emissions were reduced by 20% in four Northern Hemispheric regions. The figure shown here illustrates the decline in maximum daily 8-hr average (MDA8) O3 during spring for 9 regions across the U.S. attributable to emissions reductions in three foreign source regions.



Large concentrations of particulate mercury (PHg) were observed in 15 events at the the Mount Bachelor Observatory from 2005-2007. Using a combination of air-mass back-trajectories and chemical tracer data, we conclude that these events were due to regional wildfires. Based on the observed PHg/CO ratio, we calculate that global wildfires are a source of PHg comparable to anthropogenic sources. These results are presented in a new paper accepted for publication in Atmospheric Environment.



An article by Phil Swartzendruber, Dan Jaffe, and Brandon Finley on the development of a higher time resolution technique for measuring gaseous oxidized mercury (RGM), is currently in-press in Environmental Science & Technology. Two existing approaches, speciation by difference and direct collection on denuders, are combined to allow for 2.5 minute resolution for higher RGM concentrations, and direct collection on denuders for lower concentrations. The system was flown in the Pacific Northwest northwest in five test flights and detected several pockets of air with enhanced RGM, consistent with previous observations at Mt. Bachelor.


This figure shows the vertical distribution of gaseous elemental mercury (GEM), total airborne mercury (THg), reactive (oxidized) gaseous mercury (RGM), and ozone, on Aug 23, 2008. High levels of oxidized mercury are observed above 850 mb with low and moderate ozone.

A new article submitted to Atmospheric Environment by Brandon Finley, Phil Swartzendruber, and Dan Jaffe shows that wildfires are a major source of particulate mercury (PHg) in the Pacific Northwest. Emissions of PHg were observed in 16 wildfire plumes sampled at the Mount Bachelor Observatory from 2005-2007. Wildfires were identified using back-trajectory analysis and MODIS fire data. Using the measured PHg/CO ratio and estimates of global CO produced from wildfires, we estimate that wildfire sources of PHg are comparable to anthropogenic sources.

Finley, B. D., Swartzendruber, P., & Jaffe, D. A. Large particulate mercury emissions from wildfires at the Mount Bachelor Observatory.

The interannual variability of long-range transport (LRT) of CO to the west coast of the U.S. was investigated with MBO and ESRL ground station data, MOPITT and TES satellite retrievals and GEOS-Chem model output. We reveal a significant enhancement in LRT of CO during spring 2005 vs. spring 2006. This was due to the combination of differing transport pathways, synoptic conditions over the NE Pacific and anomalously strong biomass burning in SE Asia during winter 2004 - spring 2005.

Reidmiller, D. R., D. A. Jaffe, D. Chand, P. Swartzendruber, S. Strode, G. M. Wolfe and J. A. Thornton, (2009), Interannual variability of long-range transport as seen at the Mt. Bachelor Observatory. Atmos. Chem. Phys., 9, 557 - 572.

A new article by Emily Fischer shows that dust from the Gobi and Taklimakan deserts in China and Mongolia is routinely present in the air over the western United States during spring months. The article was published this month in the journal Geophysical Research Letters.

Fischer, E. V., N. C. Hsu, D. A. Jaffe, M.-J. Jeong, and S. L. Gong (2009), A decade of dust: Asian dust and springtime aerosol load in the U.S. Pacific Northwest, Geophys. Res. Lett., 36, L03821, doi:10.1029/2008GL036467.

Zhang L., D. J. Jacob, K. F. Boersma, D. A. Jaffe, J. R. Olson, K. W. Bowman, J. R. Worden, A. M. Thompson, M. A. Avery, R. C. Cohen, J. E. Dibb, F. M. Flock, H. E. Fuelberg, L. G. Huey, W. W. McMillan, H. B. Singh, and A. J. Weinheimer. Transpacific transport of ozone pollution and the effect of recent Asian emission increases on air quality in North America: an integrated analysis using satellite, aircraft, ozonesonde, and surface observations. Atmos. Chem. Phys., 8, 6117-6136, 2008

Zhang 2008

New article by Nicola Pirrone (Italy-UNEP) stresses the value
of the Mt. Bachelor observations.


"A network of mercury monitoring stations ideally would include background sites such as those in the WMO's Global Atmospheric Watch initiative, as well as strategic high altitude sites on known long range transport routes such as Mount Bachelor in Oregon (Jaffe and Strode, 2008) and Mauna Loa in Hawaii."

Atmos. Env.

Seattle is in violation of the new, tougher O3 standard.

Going over the legal limit for smog over the weekend means officials here will have to devise a plan to improve air quality in the region.

Read the article:

http://seattlepi.nwsource.com/local/375427_airpollution19.html

This figure shows the relationship between summer mean O3 measured at 9 NPS/CASTNET sites in the Western US along with summer area burned for 1989-2004. Large fire years, such as 1994, 1996, 2000 and 2002, have significantly more O3. The relationship is statistically robust. In the publication the impacts of fires on different scales around each monitoring site.


Influence of fires on air quality.

Interannual Variations in PM2.5 due to Wildfires in the Western United States. Dan Jaffe, William Hafner, Duli Chand, Anthony Westerling, and Dominick Spracklen. Environ. Sci. Technol., 42 (8), 2812–2818, 2008. 10.1021/es702755v
Environ. Sci. Technol.