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SOURCE APPORTIONMENT OF PM 2.5 AND CARBON IN SEATTLE USING CHEMICAL MASS BALANCE AND POSITIVE MATRIX FACTORIZATION
Citation:
Maykut, N., J Lewtas, AND T. V. Larson. SOURCE APPORTIONMENT OF PM 2.5 AND CARBON IN SEATTLE USING CHEMICAL MASS BALANCE AND POSITIVE MATRIX FACTORIZATION. Presented at AWMA/AGU International Specialty Conference, Bend, OR, October 2-5, 2001.
Impact/Purpose:
The objective of this task is to develop and evaluate personal exposure and biomarker methods for toxic components associated with PM2.5 and SVOC in population exposures. Specific sub-objectives include the following:
1) Identification and quantification of either toxic or tracer organic chemicals associated with PM2.5 and associated SVOC.
2) Measurement of personal airborne exposure of selected toxic/tracer organic species in population based human exposure studies.
3) Development and application of urinary metabolite and other biomarker methods for these toxic/tracer organic species in human exposure studies.
4) Evaluation of multivariant receptor models for apportioning personal exposure using biomarker data.
Description:
Three years of PM2.5 speciated data were collected and chemically analyzed using the IMPROVE protocol at the Beacon Hill site in Seattle. The data were analyzed by the Chemical Mass Balance Version 8 (CMB8) and Positive Matrix Factorization (PMF) source apportionment models. These models were used to identify the major sources of PM2.5, organic and elemental carbon. The major sources of PM2.5 identified by the PMF model are vegetative burning and diesel vehicles. This is generally consistent with the CMB8 analysis which also identified motor vehicles (combined diesel and gasoline) and vegetative burning as major sources. Both models identified secondary sulfate and nitrate as contributing 20-30% of the PM2.5. Using individual organic carbon (OC) and elemental carbon fractions (EC) in the PMF analysis allowed this model to allocate the PM2.5, OC and EC to vegetative burning, diesel vehicles, gasoline vehicles, fuel oil and secondary sources associated with sulfates. A major difference in the results from the two models was the split between vegetative burning and motor vehicles. In the PMF analysis vegetative burning accounted for 35% of the mass, 57% of the OC and 47% of the EC. The CMB8 model attributed 17% of the PM2.5 mass to vegetative burning. Using CMB, motor vehicles accounted for the largest source of PM2.5 (44%). Using the PMF model, two motor vehicle source profiles were identified. One profile clearly corresponded to diesel vehicles (16% PM2.5) and accounted for 36% of the total EC and 19% of the total OC in the aerosol. The second motor vehicle source profile was less dominated by EC and likely represents the gasoline and other non-diesel mobile sources. This motor vehicle source accounted for 6% of PM2.5, 4.5% of the total OC, and 1% of the EC.
This work has been funded by the U S Environmental Protection Agency. It has been subjected to Agency review and approved for publication.