『Abstract
Trace elements, especially those associated with fine particles
in airborne particulate matter (PM), may play an important role
in PM adverse health effect. The aim of this paper is to characterize
elements in a wide particle size range from nano (57-100 nm) to
fine (100-1,000 nm) and to coarse (1,000-10,000 nm) fractions
of two urban PM samples collected in Ottawa. Size-selective particle
sampling was performed using a micro-orifice uniform deposit impactor,
and element concentrations were determined in each different size
fraction by inductively coupled plasma-mass spectroscopy. A general
trend of increasing element concentration with decreasing aerodynamic
diameter was observed for elements V, Mn, Ni, Cu, Zn, Se, and
Cd, indicating they were predominately concentrated in the nanoparticle
size range. Other elements including Fe, Sr, Mo, Sn, Sb, Ba, and
Pb were predominately concentrated in the fine-size range. Increased
concentration of elements in the nano and fine particle size range
is significant due to their ability to penetrate into the deepest
alveolar area of the lungs. This was confirmed by the calculation
of median concentration diameters, which were less than 800 nm
for most of the investigated elements. Particle size distribution
and element correlation analysis suggest that the elements concentrated
in the nano- and fine-size fractions originated mainly from vehicular
combustion and emission. Kong-range airborne transport and soil
or road dust resuspension may also contribute. Particle size had
an important effect on element bioaccessibility for the studied
urban PM samples showing a general trend of increasing element
bioaccessibility with decreasing particle size. These results
emphasize the importance of acquiring information on nano and/or
fine PM-bound elements and their bioaccessibilities for accurate
element and PM exposure assessment.
Keywords: Airborne particulate matter (PM); Metal; Air pollution;
Element bioaccessibility; Particle size distribution; Nanoparticles;
ICP-MS』
1. Introduction
2. Experimental
2.1. Sampling and mass measurement
2.2. Filter digestion, extraction, and multi-element determination
2.3. Quality assurance
3. Results and discussion
3.1. PM and element mass distribution
3.2. Median values and element concentration ranges
3.3. Size distribution
3.3.1. EHC-93 samples
3.3.2. EHC-2K samples
3.4. Particle size dependent bioaccessibility
4. conclusions
Acknowledgments
References