Details

Autor(en) / Beteiligte

• Clements, Andrea L.
• Fraser, Matthew P.
• Upadhyay, Nabin
• Herckes, Pierre
• Sundblom, Michael
• Lantz, Jeffrey
• Solomon, Paul A.

Titel

Characterization of summertime coarse particulate matter in the Desert Southwest-Arizona, USA

Ist Teil von

• Journal of the Air & Waste Management Association (1995), 2013-07, Vol.63 (7), p.764-772

Ort / Verlag

Pittsburgh, PA: Taylor & Francis Group

Erscheinungsjahr

2013

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• A year-long study was conducted in Pinal County, AZ, to characterize coarse (2.5 - 10 μm aerodynamic diameter, AD) and fine (< 2.5 μm AD) particulate matter (PMc and PMf, respectively) to further understand spatial and temporal variations in ambient PM concentrations and composition in rural, arid environments. Measurements of PMc and PMf mass, ions, elements, and carbon concentrations at one-in-six day resolution were obtained at three sites within the region. Results from the summer of 2009 and specifically the local monsoon period are presented. The summer monsoon season (July - September) and associated rain and/or high wind events, has historically had the largest number of PM 10 NAAQS exceedances within a year. Rain events served to clean the atmosphere, decreasing PMc concentrations resulting in a more uniform spatial gradient among the sites. The monsoon period also is characterized by high wind events, increasing PMc mass concentrations, possibly due to increased local wind-driven soil erosion or transport. Two PM 10 NAAQS exceedances at the urban monitoring site were explained by high wind events and can likely be excluded from PM 10 compliance calculations as exceptional events. At the more rural Cowtown site, PM 10 NAAQS exceedances were more frequent, likely due to the impact from local dust sources. PM mass concentrations at the Cowtown site were typically higher than at the Pinal County Housing and Casa Grande sites. Crustal material was equal to 52-63% of the PMc mass concentration on average. High concentrations of phosphate and organic carbon found at the rural Cowtown were associated with local cattle feeding operations. A relatively high correlation between PMc and PMf (R 2  = 0.63) indicated that the lower tail of the coarse particle fraction often impacts the fine particle fraction, increasing the PMf concentrations. Therefore, reductions in PMc sources will likely also reduce PMf concentrations, which also are near the value of the 24-hr PM 2.5 NAAQS.