Chemical Composition of PM2.5 over N. America
Big Bend(scale 0-15 ug/m3)
G.Smoky Mtn.
Yellowstone Mammuth CaveSequoia
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Aerosol Types• Aerosol are composed of multiple types. Each type may be considered a different
pollutant since it has its own class of sources, aerosol properties and is associated with different effects.
• In other words, sulfate, nitrate organics, dust (soil) components of PM have no more commonalities then CO, NOx and SO2.
• The aerosol types are lumped into “PM2.5” by the current regulations.
• The IMPROVE aerosol types are:
SULFATE = 4.125*S Ammonium sulfate
NITRATE = 1.29*NO3 Ammonium nitrate
ORGANICS = 1.4(O1+O2+O3+O4+OP) 1.4* various organics (OMC)
SOOT = E1+E2+E3+OP Light absorbing carbon (LAC)
SOIL = 2.2AL++2.49SI+1.63CA+2.42FE+1.94TI Crustal elements
FMASS = SULFATE + NITRATE + LAC + OCM + SOIL Reconstructed fine mass
CMASS = MT-MF Coarse=PM10-FMASS
Issue: Each aerosol type has many variants in nature. I think that the IMPROVE typing (aggregation) used by Malm & Co is good and it should be retained for presenting the network results. Need for alternative aggregations? I am open for discussion RBH.
Method: Cumulative Seasonal PM2.5 Composition
• PM2.5 chemical components were calculated based on the CIRA methodology
• In addition, the the organics were (tentatively) further separated as Primary Smoke Organics (red) and Remainder organics (purple)
PSO = 20*(K - 0.15*Si – 0.02* Na) Remainder Org = Organics - PSO
• Also, the ‘Unknown’ mass (white area) is the difference between the gravimetrically measured and the chemically reconstructed PM2.5.
• The daily chemical composition was aggregated over the available IMPROVE data range (1988-99) to retain the seasonal structure.
• I order to reduce the noise the daily data were smoothed by a 15-day moving average filter.
Shenandoah
Regional Grouping of Sites
• IMPROVE sites were grouped as follows:
– New England ()
– Mid-Atlantic ()
– Central EUS ()
– Peripheral ()
Peripheral Sites: Chemical Mass Balance• Eastern N. America is
surrounded by aerosol source regions such as Sahara and Central America.
• As a consequence, the PM concentration at the ‘edges’ ranges between 4-15 ug/m3; much of it originating outside.
• The chemical composition of the inflow varies by location and season.
• Sahara dust, and smoke from Central America and W. US/Canada are the main contributions.
Badlands(scale 0-15 ug/m3)
Big Bend(scale 0-15 ug/m3)
Voyageurs(scale 0-15 ug/m3)
Acadia
Everglades
Peripheral Sites
Badlands(scale 0-15 ug/m3)
Big Bend(scale 0-15 ug/m3)
Voyageurs(scale 0-15 ug/m3)
Acadia
Everglades
Upper Buffalo Mammuth Cave Shining Rock
G.Smoky Mtn.Sipsy
Mid-Atlantic Region
Shenandoah Washington DC Brigantine
Dolly Sods Jefferson
New England Region
Lye Brook
MoosehornAcadiaProctor Maple
Ringwood
Upper Midwest
Badlands
Voyageurs
TX, NM
Chiricahua
Bandelier White River Guadalupe
Big Bend
TX, NM
Tonto Petrified For. Saguaro
Chiricahua
TX, NM
Tonto Petrified For. Saguaro
Chiricahua
Idaho
Tonto Three Sisters Yellowstone
Bridger
Jawbridge
Great Basin
California - Background
Bliss State(2043 m)
Lessen(1800 m)
Crater Lake(1980 m)
Point Reyes(38 m, Beach)
California - Perturbed
Yosemite S. Lake Tahoe Sequoia
San GorgonioPinnacles
Northwest - Perturbed
Abbotsford
(0 m)
Chilliwack
(9 m)
Puget Sound
(99 m)
Columbia River
(90 m)Mt. Rainier
(436 m)
Remote ‘Global’ Sites
Denali
(640 m)
Virgin Islands
(46 m)Mauna Loa
(3398 m)
Chemical Speciation of the Fine Mass Based on IMPROVE
• See Sisler & Malm
• Over the remote Eastern US, sulfates dominate the Fine Mass
• The Southeast is also influenced by ‘smoke’ (organics+LAC) and dust.
• Over the West, organics, nitrates and dust dominate