Source characterization of major emission sources in the Imperial and Mexicali Valleys along the US/Mexico border

Chemical profiles for particle emissions are needed for source apportionmen t studies using the chemical mass balance (CMB) receptor model. Source meas urements of geological sources, motor vehicle exhaust. vegetative burning ( e.g. asparagus, field burning, charbroil cooking), and industrial sources ( e.g. oil-fueled glass plant, manure-fueled power plants) were acquired as p art of the Imperial/Mexicali Valley Cross Border PM,) Transport Study in 19 92. Six different source sampling techniques (i.e. hot- and diluted-exhaust sampling, ground-based source sampling, particle sweeping/grab sampling, v acuum sampling, and laboratory resuspension sampling) were applied to acqui re filter samples of PM2.5 and PM10 (particulate matter with aerodynamic di ameters <2.5 and 10 mum, respectively). Filter samples were analyzed for ma ss by gravimetry, elements (Na to U) by X-ray fluorescence, anions (Cl-, NO 3-, SO4=) by ion chromatography, ammonium (NH4+) by automated colorimetry, soluble sodium (Na-) and potassium (K+) by atomic absorption spectrophotome try. and organic and elemental carbon (OC, EC) by thermal/optical reflectan ce. Concentration data were acquired for a total of similar to 50 chemical species. Elevated abundances of crustal components (Al. Si. K, Ca, Fe) from geological material, carbon (OC, EC) and trace elements (Br, Pb) from vehi cle exhausts, carbon (OC. EC) and ions (K+, Cl-) from vegetative burning, i ons (SO4=, NH4+, Na+. K+, Cl-) and elements (Cl. SO from a manure-fueled po wer plants, and sulfur and trace elements (Na, Pb, Se, Ni, V) from an oil-f ueled glass plant were found in the resulting source profiles. Abundances o f crustal species (e.g. Al, Si, Ca) in the Imperial/Mexicali Valley geologi cal profiles are more than twice those found in central and southern Califo rnia. Abundances of lead in motor vehicle exhausts indicate different vehic le fleets in border cities. Emission profiles from field burning and charbr oil cooking specific to the border area show that a majority (> 60%) of emi ssions are comprised of carbon, with high organic to total carbon ratios (0 .93 to 0.97). Abundances of sulfate and ammonium account for nearly 60% of the manure-fueled power plant's emissions. Elevated levels of metals (Na+, Pb, Cd. Se) and byproducts of petroleum combustion (S, Ni. V) were found in the oil-fueled glass plant's emissions., (C) 2001 Elsevier Science B.V. Al l rights reserved.