A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Particle size distributions of metal and non-metal elements in an urban near-highway environment
Abstract Determination of the size-resolved elemental composition of near-highway particulate matter (PM) is important due to the health and environmental risks it poses. In the current study, twelve 24h PM samples were collected (in July–August 2006) using a low-pressure impactor positioned 20m from a Raleigh, North Carolina interstate. The interstate supported ∼125,000vehicles/d, the majority of which were light-duty gasoline passenger vehicles. The overall near-highway PM mass size distribution was trimodal with a major accumulation mode peak at 500–800nm. PM mass levels reflected daily traffic activity, while mean near-highway PM10 (33±7.5μgm−3), PM2.5 (29±6.8μgm−3), and PM0.1 (1.4±0.3μgm−3) mass levels varied less than 24% over the two week sampling period. The elemental composition of the impactor-collected PM was investigated using magnetic sector inductively coupled plasma-mass spectroscopy (SF-ICPMS). Accumulation mode sulfur (7±4% w/w) was the major inorganic constituent detected at the near-highway site followed by coarse mode group IA and IIA elements likely from re-suspension of crustal matter. As expected, elements regularly detected in asphalt, vehicle, catalyst (e.g., Pt, Rh, and Pd), brake, and tire wear (e.g., Cu and Sb) were also found in the near highway PM. Maximum concentrations of the platinum group, rare earth, and common brake and tire wear elements were observed at d 50 =1–2μm, d 50 =1–4μm, and d 50 ≥1–4μm, respectively. Ten of the eleven metals listed as EPA air toxics (Mn, Cr, Sb, Ni, Pb, As, Co, Cd, Se, and Be) were detected in each PM size fraction but were generally enriched in PM0.1. Several biologically antagonistic suites of metals (Cd, Cu, and V) were found in multiple PM size modes. Some of these metals showed erratic size distributions with daily changes in enrichment (e.g., Ni, Zn, Cd, As, and Cu) and particle size, suggesting a variety of emissions and metal exposure scenarios occurring in the near-highway environment.
Research highlights ► Daily changes in metal (Ni, Zn, Co, and Cr) size distributions and proportions in particle matter suggest a variety of metal exposure scenarios are possible in the near-highway environment. ► Hazardous metal air pollutants in the near-highway atmosphere tend to concentrate in ultrafine particles. ► Pb and As levels are well correlated, unimodally distributed, and show traffic-influenced concentration changes in the near-highway environment.
Particle size distributions of metal and non-metal elements in an urban near-highway environment
Abstract Determination of the size-resolved elemental composition of near-highway particulate matter (PM) is important due to the health and environmental risks it poses. In the current study, twelve 24h PM samples were collected (in July–August 2006) using a low-pressure impactor positioned 20m from a Raleigh, North Carolina interstate. The interstate supported ∼125,000vehicles/d, the majority of which were light-duty gasoline passenger vehicles. The overall near-highway PM mass size distribution was trimodal with a major accumulation mode peak at 500–800nm. PM mass levels reflected daily traffic activity, while mean near-highway PM10 (33±7.5μgm−3), PM2.5 (29±6.8μgm−3), and PM0.1 (1.4±0.3μgm−3) mass levels varied less than 24% over the two week sampling period. The elemental composition of the impactor-collected PM was investigated using magnetic sector inductively coupled plasma-mass spectroscopy (SF-ICPMS). Accumulation mode sulfur (7±4% w/w) was the major inorganic constituent detected at the near-highway site followed by coarse mode group IA and IIA elements likely from re-suspension of crustal matter. As expected, elements regularly detected in asphalt, vehicle, catalyst (e.g., Pt, Rh, and Pd), brake, and tire wear (e.g., Cu and Sb) were also found in the near highway PM. Maximum concentrations of the platinum group, rare earth, and common brake and tire wear elements were observed at d 50 =1–2μm, d 50 =1–4μm, and d 50 ≥1–4μm, respectively. Ten of the eleven metals listed as EPA air toxics (Mn, Cr, Sb, Ni, Pb, As, Co, Cd, Se, and Be) were detected in each PM size fraction but were generally enriched in PM0.1. Several biologically antagonistic suites of metals (Cd, Cu, and V) were found in multiple PM size modes. Some of these metals showed erratic size distributions with daily changes in enrichment (e.g., Ni, Zn, Cd, As, and Cu) and particle size, suggesting a variety of emissions and metal exposure scenarios occurring in the near-highway environment.
Research highlights ► Daily changes in metal (Ni, Zn, Co, and Cr) size distributions and proportions in particle matter suggest a variety of metal exposure scenarios are possible in the near-highway environment. ► Hazardous metal air pollutants in the near-highway atmosphere tend to concentrate in ultrafine particles. ► Pb and As levels are well correlated, unimodally distributed, and show traffic-influenced concentration changes in the near-highway environment.
Particle size distributions of metal and non-metal elements in an urban near-highway environment
Hays, Michael D. (author) / Cho, Seung-Hyun (author) / Baldauf, Richard (author) / Schauer, James J. (author) / Shafer, Martin (author)
Atmospheric Environment ; 45 ; 925-934
2010-11-06
10 pages
Article (Journal)
Electronic Resource
English
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