Application of Synchrotron Microprobe Methods to Solid-Phase Speciation of Metals and Metalloids in House Dust

Abstract

Determination of the source and form of metals in house dust is important to those working to understand human and particularly childhood exposure to metals in residential environments. We report the development of a synchrotron microprobe technique for characterization of multiple metal hosts in house dust. We have applied X-ray fluorescence for chemical characterization and X-ray diffraction for crystal structure identification using microfocused synchrotron X-rays at a less than 10 μm spot size. The technique has been evaluated by application to archived house dust samples containing elevated concentrations of Pb, Zn, and Ba in bedroom dust, and Pb and As in living room dust. The technique was also applied to a sample of soil from the corresponding garden to identify linkages between indoor and outdoor sources of metals. Paint pigments including white lead (hydrocerussite) and lithopone (wurtzite and barite) are the primary source of Pb, Zn, and Ba in bedroom dust, probably related to renovation activity in the home at the time of sampling. The much lower Pb content in the living room dust shows a relationship to the exterior soil and no specific evidence of Pb and Zn from the bedroom paint pigments. The technique was also successful at confirming the presence of chromated copper arsenate treated wood as a source of As in the living room dust. The results of the study have confirmed the utility of this approach in identifying specific metal forms within the dust.

Heavy metal pollution in soils and urban-grown organic vegetables in the province of Sevilla, Spain

“…Barium sulphate (barite) is a common component of white paint pigments, such as lithopone (a mixture of barium sulphate and zinc oxide) (Walker et al 2011). It is common to find the metals Pb, Ba and also Zn, together in paints and paint-polluted soils (Harroun et al 2011;Turner and Lewis 2018;Walker et al 2011) with Pb and Ba being highly available (Turner and Lewis 2018).…”

Rare earth elements and select actinoids in the Canadian House Dust Study

“…Based on the recent unprecedented increase in extraction and manufacturing applications of rare earth elements (REE), a concomitant increase in environmental and occupational exposures to REE can be expected . It is recognized that settled house dust acts as a sink for metal compounds used in consumer products and building materials, and as the commercial importance and prevalence of REE in consumer products grows, information about REE concentrations in house dust is likely to become increasingly relevant. To date, almost nothing has been published on REE concentrations in settled house dust, apart from a small study in New Zealand which reported on Sc, La, Ce, and Sm concentrations in 11 urban homes.…”

Geochemical and mineralogical controls on metal(loid) dispersion in streams and stream sediments in the Prairie Creek district, NWT

“…Characterization was accomplished using optical microscopy, scanning electron microscope (SEM, Quanta 650 FEG-ESEM), electron microprobe (JEOL JXA-8230), and synchrotron-based micro X-ray diffraction (μ-XRD) and micro X-ray fluorescence (μ-XRF). Synchrotron microanalysis employed methods reported previously (Walker et al 2009(Walker et al , 2011. Polished thin sections were lifted from the glass slides using HPLC-grade acetone and carefully placed on polyimide (Kapton) tape.…”