Trace metals in ambient air: Hourly size-segregated mass concentrations determined by synchrotron-XRF.
Trace metals are ubiquitous in urban ambient air, with mass concentrations in the range of a few microg/m3 down to less than 100 pg/m3. To measure such low concentrations represents a challenge for chemical and physical analysis. In this study, ambient aerosol was collected in Zürich (Switzerland) in 1-h intervals and three size fractions (aerodynamic diameters 0.1-1 microm, 1-2.5 microm, and 2.5-10 microm), using a three-stage rotating drum impactor (RDI). The samples were analyzed by energy-dispersive Synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) to obtain size-segregated hourly elemental aerosol mass concentrations for Cr, Mn, Fe, Cu, Zn, Br, and Pb, along with S, Cl, and Ca under the selected experimental conditions. The high sensitivity of SR-XRF allowed for detection limits of <50 pg/m3 for most of the above elements, with a net analysis time of only 15 s per sample. The data obtained with this technique illustrate that there is a considerable gain of relevant information when time resolution for measurements is increased from 1 day to 1 h. The individual size fractions of a specific element may show significantly different short-term patterns.
Bukowiecki
Nicolas
N
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland. nicolas.bukowiecki@psi.ch
Hill
Matthias
M
Gehrig
Robert
R
Zwicky
Christoph N
CN
Lienemann
Peter
P
Hegedüs
Ferenc
F
Falkenberg
Gerald
G
Weingartner
Ernest
E
Baltensperger
Urs
U
D000336:Aerosols; D000388:Air / Q000032:analysis* / Q000592:standards; D000393:Air Pollutants / Q000032:analysis*; D010316:Particle Size; D013052:Spectrometry, X-Ray Emission; D013557:Switzerland; D017356:Synchrotrons; D013997:Time Factors; D014131:Trace Elements / Q000032:analysis*
D000336:Aerosols; D000393:Air Pollutants; D014131:Trace Elements