Abstract
Abstract. A method to detect and quantify mass concentrations of trace metals on soot particles by the Aerodyne soot-particle aerosol mass spectrometer (SP-AMS) was developed and evaluated in this study. The generation of monodisperse Regal black (RB) test particles with trace amounts of 13 different metals (Na, Al, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr and Ba) allowed for the determination of the relative ionization efficiency of each metal relative to black carbon (RIEmeas). The observed RIEmeas / RIEtheory values were larger than unity for Na, Rb, Ca, Sr and Ba due to thermal surface ionization (TSI) on the surface of the laser-heated RB particles. Values closer to unity were obtained for the transition metals Zn, Cu, V and Cr. Mn, Fe, and Ni presented the lowest RIEmeas / RIEtheory ratios and highest deviation from unity. The latter discrepancy is unexplained; however it may be related to problems with our calibration method and/or the formation of metal complexes that were not successfully quantified. The response of the metals to the laser power was investigated and the results indicated that a minimum pump laser current of 0.6 A was needed in order to vaporize the metals and the refractory black carbon (rBC). Isotopic patterns of metals were resolved from high-resolution mass spectra, and the mass-weighted size distributions for each individual metal ion were obtained using the high-resolution particle time-of-flight (HR-PToF) method. The RIEmeas values obtained in this study were applied to the data of emission measurements in a heavy-fuel-oil-fired heating station. Emission measurements revealed a large number of trace metals, including evidence for metal oxides and metallic salts, such as vanadium sulfate, calcium sulfate, iron sulfate and barium sulfate, which were identified in the SP-AMS high-resolution mass spectra. SP-AMS measurements of Ba, Fe, and V agreed with ICP-MS analyzed filter samples within a factor of 2 when emitted rBC mass loadings were elevated.
Highlights
Trace metals are found in atmospheric aerosol particles from various combustion processes, such as vehicular emissions and industrial sources (Gao et al, 2002; Mbengue et al, 2014), and mechanical processes, such as wind-derived soil dust and sea salt (Pacyna 1998; Allen et al, 2001)
The response of the metals to the laser power was investigated and the results indicated that a minimum pump laser current of 0.6 A was needed in order to vaporize the metals and the refractory black carbon
The purpose of this study is to develop a method for the quantification of trace metal content in black carbon aerosol, such as combustion-related emissions, by using the sootparticle aerosol mass spectrometer (SP-AMS)
Summary
Trace metals are found in atmospheric aerosol particles from various combustion processes, such as vehicular emissions and industrial sources (Gao et al, 2002; Mbengue et al, 2014), and mechanical processes, such as wind-derived soil dust and sea salt (Pacyna 1998; Allen et al, 2001). S. Carbone et al.: Trace metals characterization with the SP-AMS for biomass burning; vanadium and nickel for petrochemical plants and/or fuel-oil combustion; and iron, chromium, manganese, zinc and cadmium for steelwork and smelter emissions (Querol et al, 2007, Mbengue et al, 2014). The detection of trace elements is useful in order to evaluate the engine performance in controlled engine emission experiments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
