Quantifying the Contribution of Fugitive Geological Dust to Ambient PM10 Levels in the San Joaquin Valley

Work Statement

prepared by

Countess Environmental

August 28, 2002

Countess Environmental (CE) will evaluate the contribution of fugitive geological dust to the ambient PM10 concentrations within the SJV Air Basin with a emphasis on the following issues:

temporal, spatial and chemical variations in fugitive geological dust concentrations asindicators of different fugitive geological dust sources and different source strengths;

variations in the ratio of coarse to fine size fractions of fugitive geological dust as indicators of the age of the resuspended dust as well as indicators of different fugitive geological dust sources; and

characterization of the zone of influence for sources of road dust and agricultural dust in the Corcoran/Hanford area during the Fall.

CE will utilize ambient PM10 and PM2.5 monitoring data (i.e., filter based measurements) from the CRPAQS monitoring network available from CARB, and will adopt the methodology utilized by Sisler and Malm (2000) to calculate the fugitive geological dust concentrations, [Soil], for PM samples based on XRF measurements of the major elements associated with geological material as follows:

[Soil] = 2.2 [Al] + 2.19 [Si] + 1.63 [Ca] + 2.42 [Fe] + 1.94 [Ti]

CE will calculate daily 24-hour as well as seasonal and annual PM10 fugitive geological dust concentrations for the seven CRPAQS community exposure sites where PM10 Minivols were deployed. CE will quantify the spatial variation in PM10 fugitive geological dust concentrations for each of these seven sites for daily 24-hour measurements as well as the seasonal and annual average results. CE will also quantify the spatial variation in PM10 fugitive geological dust concentrations for the 11 satellite (source zone of influence/receptor zone of representation) sites centered around Corcoran during the Fall of 2000. CE will compare the results from the period December 1999 through January 2000 with the results from the period December 2000 through January 2001 to determine the variability from one year to the next.

CE will investigate the temporal and spatial variations in the relative abundance of the six major elements associated with geological material (e.g., [Al]/{[Al] + [Si] + [K] + [Ca] + [Ti] + [Fe]})for all the sites where PM10 Minivols were deployed. These results will be used to determine if certain elements are enriched compared to site average values or network average values. CE will also calculate the [K]/[Fe] ratio for all the sites where PM10 Minivols were deployed to determine if ambient PM10 concentrations are impacted by wood burning or forest fires. CE will examine the results from the five “source zone of influence” sites (unpaved railroad shoulder, paved dairy road, unpaved dairy road, grain elevators, cotton handling) centered around Corcoran to see if the variation in the relative concentration of the major elements associated with geological material from these sites can be used as an indicator of the sources of fugitive dust (agricultural dust, road dust, or mixed) at each CORE site.

CE will utilize the data from the collocated PM10 Minivols and PM2.5 Minivols deployed at Corcoran, Modesto, Oildale and Visalia to evaluate the variation in the coarse to fine size fractions of fugitive geological dust. The coarse fraction will be calculated as the difference between the PM10 Minivol data and the PM2.5 Minivol data. CE will analyze the PM2.5 Minivol data available from the one background PM2.5 monitoring site employed during CRPAQS (Olancha)to quantify the fine fraction of ambient fugitive geological dust concentrations at this background site. CE will use these results as well as the results from the four sites with collocated PM10 and PM2.5 Minivols to estimate the seasonal average and annual average PM10 fugitive geological dust concentrations for this background site. CE will compare the results from the period December 1999 through January 2000 with the results from the period December 2000 through January 2001 to determine the variability from one year to the next.

For the samples collected with the PM10 Minivols, CE will calculate:

the fugitive geological dust concentration in the PM10 size fraction, [PM10 Soil];

the fugitive geological dust contribution to PM10 mass, [PM10 Soil] / [PM10];

the relative abundance of each of the six major elements associated with geological material (Al, Si, Ca, Fe, K, Ti); and

the potassium to iron ratio, [K]/[Fe].

CE will document the spatial, temporal and chemical variations observed for each of these analyses. CE will examine the data to determine whether there is a “weekend/weekday effect” associated with the amount and relative contribution of fugitive geological dust to ambient levels of PM10. CE will compare the relative contribution of fugitive geological dust to ambient PM10 mass concentrations (as measured by the PM10 Minivols) with the estimates of fugitive dust contributions in the SJVUAPCD’s PM10 emissions inventory.

For the four sites that have both PM2.5 Minivol and PM10 Minivol measurements (Corcoran, Modesto, Oildale, and Visalia), CE will calculate:

the fugitive geological dust concentration in the fine size fraction, [Fine Soil];

the fugitive geological dust contribution to fine mass, [Fine Soil]/[PM2.5].

the coarse mass concentration [CM], where [CM] equals [PM10] minus [PM2.5];

the fugitive geological dust concentration in the coarse size fraction, [Coarse Soil], where [Coarse Soil] equals [PM10 Soil] minus [Fine Soil];

the fugitive geological dust contribution to coarse mass, [Coarse Soil] / [CM]; and

the ratio of coarse to fine fugitive geological dust, [Coarse Soil]/[Fine Soil].

CE will document the spatial and temporal variations observed for each of these analyses. The ratio of coarse to fine fugitive geological dust measured in the ambient samples will be compared to EPA’s estimates for freshly generated emissions of fugitive geological dust associated with roads, construction, and agriculture.

For the three sites that have daily 24-hour PM2.5 Sequential Filter Sampler (SFS) measurements (Angiola, Bakersfield, and Modesto), CE will investigate:

temporal variations in fine fugitive geological dust concentration, [Fine Soil]; and

fine fugitive geological dust contribution to fine particulate mass, [PM2.5 Soil] / [PM2.5].

CE will also estimate the seasonal and annual average PM10 fugitive geological dust concentrations for the Angiola site utilizing the average PM10/PM2.5 ratios of ambient concentrations of fugitive geological dust for the four sites with collocated PM10 and PM2.5 Minivols.

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