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