Contribution of Water to Particulate Mass in the South Coast Air Basin

The Use of Ambient Measurements To Identify which Precursor Species Limit Aerosol Nitrate Formation

“…The SCAQS PM concentrations were higher during winter than during summer, so the winter samples are of more interest from a regulatory perspective. The better agreement between SCAPE-predicted and measured gas-aerosol partitions for winter than for summer SCAQS samples is probably because the winter samples were more concentrated 38 and their relative measurement uncertainties were lower. The deviations between predicted and measured values for some samples were such that more aerosol NO 3 was measured than predicted, which has been attributed to variations of temperature and humidity within the 4-to 7-hr periods during which SCAQS samples were collected, and possibly to the presence of supersaturated water.…”

“…The deviations between predicted and measured values for some samples were such that more aerosol NO 3 was measured than predicted, which has been attributed to variations of temperature and humidity within the 4-to 7-hr periods during which SCAQS samples were collected, and possibly to the presence of supersaturated water. 38 The measured and calculated concentrations also showed better agreement for PM 2.5 than for PM 10 , 38 which may be a consequence of longer equilibration times for larger particles. 12,38 Only the PM 2.5 measurements are used in the present study.…”

“…38 The measured and calculated concentrations also showed better agreement for PM 2.5 than for PM 10 , 38 which may be a consequence of longer equilibration times for larger particles. 12,38 Only the PM 2.5 measurements are used in the present study.…”

“…12,38 However, many summer SCAQS samples from Long Beach were not at equilibrium, 12 and measurements (not used here) from San Nicolas Island, located ~100 km offshore, were also not consistent with thermodynamic equilibrium. 38 In the present study, only the winter SCAQS data are used, and no data are used from San Nicolas Island. The SCAQS PM concentrations were higher during winter than during summer, so the winter samples are of more interest from a regulatory perspective.…”

Analysis of the Measurement Difference for the PM10 Concentrations between Beta-ray Absorption and Gravimetric Methods at Gosan

“…The factors that may lead to the differences between the measurement methods are the differences in the (1) cut off diameters (Tsai and Cheng, 1996), (2) flow rates, (3) materials of the filters (Lipfert, 1994;Kim, 2000), (4) water content of aerosol (Meng et al, 1995 ;Chang et al, 2001;Tsai et al, 2006), (5) volatilization loss of volatile species of aerosols (Zhang and McMurry, 1992;Turpin et al, 2000;Kim, 2000;Kim and Kim, 2007), and (6) conditions of measurement (Chang et al, 2001;Kajino et al, 2006). Tsai and Cheng (1996) showed that the PM 10 concentration by a Kimoto BAM was lower than GMM because the cut off diameter of inlet at Kimoto BAM was smaller than GMM.…”