Coarse Particulate Matter Apportionment around a Steel Smelter Plant

Abstract

The results from a study carried out in the urban area of Genoa, Italy, where a large steel smelter recently shut down are presented. We had the opportunity to sample particulate matter (PM) before and after plant closure and, therefore, to measure the changes in concentration and composition of PM 10 (atmospheric PM with aerodynamic diameter Ͻ10 m). Elemental concentrations of Na to Pb were obtained through energy dispersive X-ray fluorescence (ED-XRF), and the contributions of specific sources of PM 10 were calculated by positive matrix factorization (PMF). The PM 10 average concentration turned out to be surprisingly similar before and after closing of the smelter. Nevertheless, the comparison among data collected in the two periods (plant operating and closed), even with the limited information provided by ED-XRF, allowed us to single out two sources of PM related to the smelter activities, to extract their emission profile, and to quantify the impact of the plant on PM 10 levels. INTRODUCTIONIn recent years, atmospheric aerosols have been studied extensively, and strong relationships among heterogeneous chemistry, cloud formation, and climate forcing have been observed. 1,2 Effects on the health of humans are also well established and, for instance, in accordance with the European Directive 1999/30/EC in 2005, the concentration of PM 10 (particulate matter [PM] Ͻ10 m in aerodynamic diameter) in Europe should not exceed an annual average of 40 g ⅐ m Ϫ3 and should not exceed more than the daily limit of 50 g ⅐ m Ϫ3 for more than 35 days in a year. Large datasets of PM 10 concentration are collected for regulatory purposes in several countries. 3,4 However, this level of monitoring is insufficient and a measurement of the elemental and chemical composition of PM is recommended to achieve a more complete picture. The measurement of elements and/or compound concentrations can also help to trace specific emission

Analytical Methods for Physicochemical Characterization and Toxicity Assessment of Atmospheric Particulate Matter: A Review

“…Some XRF devices may offer flexibility in targeting specific elements of interest (e.g., tracers of potential PM sources or PTEs), which can be simultaneously quantified. The technique has a wide range of targetable elements, and two or more irradiation conditions can be set to optimize the analysis for low-Z (Na to Si/P) and medium-to-high-Z elements (e.g., S to Pb) [116,127,186]. XRF is a quick and straightforward tool for gathering chemical data on PM macrocomponents [115].…”

“…The quantitative XRF output is obtained in elemental concentrations in ng/m 3 by calculating the sensitivity factor for each element using standard reference materials, mass concentration in mass/area (also known as elemental thickness) from the XRF measurements, analyzed filter area, and sampling volume rate [110,118,120,121,163,[186][187][188][189][190][191] Uncertainties in the XRF measurements generally lie within the 5-15% range for most elements except for those with small atomic masses [120] or with low concentrations near instrument DLs [116]. Low-Z elements are also prone to cause X-ray self-attenuation and might require correction factors during quantification [116,186,190]. Generally, MDLs as low as 1-2 ng/m 3 for a selected number of elements have been reported [116,117,120,127,192,193].…”

“…Instrument calibration and routine calibration checks are important steps of quantitative XRF analysis procedures. During calibration, the sensitivity curve for each targeted element is developed using standard reference materials; the most commonly used ones being MicroMatter thin-film, single element and compound reference materials [116,117,127,163,186,189,190]. Other options include preparing a mix of different salt standards containing targeted elements [110] and analyzing additional samples concurrently with more reliable methods, such as ICP, to develop a custom calibration [115].…”

“…Different types of XRF have been applied to the chemical characterization of PM. The most widely employed type of XRF is an ED-XRF [115,116,118,120,127,186,188,[193][194][195], followed by WD-XRF [119,187,196] (and SR-XRF [121,191]. While these types share the typical assets of XRF, SR-XRF is evidently more sensitive than other traditional XRF techniques enabling a trace elemental analysis [121,197].…”