Optimized energy dispersive X-ray fluorescence analysis of atmospheric aerosols collected at pristine and perturbed Amazon Basin sites

Abstract

Elemental composition of aerosols is important to source apportionment studies and to understand atmospheric processes that influence aerosol composition. Energy dispersive X‐ray fluorescence spectroscopy was applied for measuring the elemental composition of Amazonian atmospheric aerosols. The instrument used was a spectrometer Epsilon 5, PANalytical B.V., with tridimensional geometry that reduces the background signal with a polarized X‐ray detection. The measurement conditions were optimized for low‐Z elements, e.g. Mg, Al, Si, that are present at very low concentrations in the Amazon. From Na to K, our detection limits are about 50% to 75% lower than previously published results for similar instrument. Calibration was performed using Micromatter standards, except for P whose standard was produced by nebulization of an aqueous solution of KH2PO4 at our laboratory. The multi‐element reference material National Institute of Standards and Technology–2783 (air particulate filter) was used for evaluating the accuracy of the calibration procedure of the 22 elements in our standard analysis routine, and the uncertainty associated with calibration procedures was evaluated. The overall performance of the instrument and validation of our measurements were assessed by comparison with results obtained from parallel analysis using particle‐induced X‐ray emission and another Epsilon 5 spectrometer. The elemental composition in 660 samples collected at a pristine site in the Amazon Basin and of 1416 samples collected at a site perturbed by land use change was determined. Our measurements show trace elements associated with biogenic aerosols, soil dust, biomass burning, and sea‐salt, even for the very low concentrations as observed in Amazonia. Copyright © 2014 John Wiley & Sons, Ltd.

Seasonal variability of heterogeneous ice formation in stratiform clouds over the Amazon Basin

“…From polarization Raman lidar measurements in Cyprus it was, for example, concluded that mineral dust contributes 10–50% to the optical extinction of smoke plumes, corresponding to a contribution between 25 and 80% to the aerosol mass [ Nisantzi et al , ]. Measurements of the dust fraction in lofted Amazonian biomass burning plumes were not reported yet, but surface in situ observations in the Amazon Basin analyzed by Arana et al [] suggest that the dust fraction is lower in that region than over Cyprus. For both the dry and wet season, observations in the vicinity of biomass burning activity yield a soil dust fraction of approximately 4% of the total particulate mass and a fraction between soil dust and black carbon of 50–60%.…”

Long-term study on coarse mode aerosols in the Amazon rain forest with the frequent intrusion of Saharan dust plumes

“…Since the late 1980s, numerous field campaigns have been conducted in the Amazon region, which focused on specific aspects of the complex atmospheric cycling for time periods of weeks, months, and in some cases up to years (e.g., Andreae et al, 1988Andreae et al, , 2004Andreae et al, , 2015Talbot et al, 1988Talbot et al, , 1990Harriss et al, 1990;Artaxo et al, 1993Artaxo et al, , 2013bMartin et al, 2010aBrito et al, 2014;Wendisch et al, 2016). In 2010/11, the Amazon tall tower observatory (ATTO) has been established ∼ 150 km northeast (NE) of the city of Manaus, Brazil, for continuous and detailed observation of meteorology, trace gases, aerosols, and ecology in order to study long-term trends of the Amazonian hydrological and biogeochemical cycling in relation to the increasing extent of manmade perturbations (Andreae et al, 2015).…”

Long-term study on coarse mode aerosols in the Amazon rain forest with the frequent intrusion of Saharan dust plumes

“…Energy dispersive x-ray fluorescence (EDXRF) analysis was used to quantify elements with atomic numbers ≥11 (Na and heavier) on the filters (Arana et al, 2014). The elements sodium (Na), magnesium 30 (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K), calcium (Ca), titanium (Ti), manganese (Mn), and iron (Fe) have been analyzed in detail in the context of this study.…”

“…The elements sodium (Na), magnesium 30 (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K), calcium (Ca), titanium (Ti), manganese (Mn), and iron (Fe) have been analyzed in detail in the context of this study. The detection limits for the individual elements are shown in Table S2, based on the work by Arana et al (2014). (Fig.…”