Source apportionment analysis of winter 2016 Neil Armstrong Academy data (West Valley City, Utah)

Abstract

A significant need exists to better characterize air pollution and its sources. This especially pertains to fine particulate matter (PM2.5). PM2.5 is chemically complex and its sources of emission and secondary production are highly variable. PM2.5 complexity is largely due to the organic fraction, which ranges from 10 to 90% of its total mass. However, the organic compounds in PM2.5 have generally not been monitored in the field due to limitations in available sampling techniques. A source apportionment study was conducted at the Neil Armstrong Academy campus, 5194 Highbury Pkwy, West Valley City, UT 84120, during January and February 2016. Among the objectives of the study was to identify winter-time sources of fine particulate material in West Valley City, Utah. Fine particulate mass and components, particulate organic marker and related gas phase species were all measured on an hourly average basis. The following hourly averaged data were used in the Positive Matrix Factorization (PMF) analysis, fine particulate mass, cations and anions, carbonaceous material, organic marker compounds, gas phase species including NOX, NO2 and CO and mass spectrometric measurements of gas phase methanol and C8 aromatics.A total of 557 hourly averaged data sets with 23 components were available for an EPA Positive Matrix Factorization (v5.0) analysis of the data set. The data were best described by a solution with 7 factors. Two of the factors were associated with emissions from mobile sources, diesel and automotive. One factor was associated with wood smoke emissions. Three factors were associated with the formation of secondary fine particulate material. The larger of the three was associated with the production of secondary nitrate and accounted for 70% of the PM2.5, while the other two were associated with secondary formation of particulate organic material from wood smoke associated gas phase organic compounds but accounted for only 3% of the total PM2.5 mass. The final factor was associated with fine particulate sulfate and SO2. Meteorological back-trajectory data clearly indicted the source was associated with emissions from a copper smelter to the west of the sampling site.