Field Portable X-ray Fluorescence Research Articles

Legacy lead arsenate soil contamination at childcare centers in the Yakima Valley, Central Washington, USA

BackgroundFrom the early 1900s to the 1950s, Yakima Valley orchards were commonly treated with lead arsenate (LA) insecticides. Lead (Pb) and arsenic (As) soil contamination has been identified on former orchard lands throughout Central Washington and pose a threat to human health and the environment. ObjectivesThe levels of Pb and As in soil and interior dust at participating childcare centers in the Upper Yakima Valley (Yakima County), Washington were sampled to explore exposure potential for young children. MethodsChildcare center soils were collected from two soil depths, homogenized, and analyzed in bulk by a field-portable X-ray fluorescence spectrometer (XRF). Interior dust wipes samples were collected from at least two locations in each facility. All soil samples >250 mg/kg Pb and/or >20 As mg/kg were sieved to 250 μm, tested by XRF a second time, and analyzed via acid digestion and inductively coupled plasma mass spectrometry (ICP-MS) analysis. ResultsBulk and sieved XRF results, as well as ICP-MS to XRF results were strongly correlated. Maximum Pb and As XRF results indicated that 4 (21%) and 8 (42%) of the 19 childcare centers surveyed exceeded the regulatory standard for Pb and As, respectively. Historic land use was significantly associated with elevated Pb and As levels. Interior dust loadings were below United States Environmental Protection Agency (EPA) guidelines. ConclusionsChildcare centers are areas of intensive use for children and when coupled with potential residential exposure in their homes, the total daily exposure is a potential hazard to children.

Rapid Analysis of the Size Distribution of Metal-Containing Aerosol.

Conventional methods to measure the metallic content of particles by size are time consuming and expensive, requiring collection of particles with a cascade impactor and subsequent metals analysis by inductively coupled plasma mass spectrometry (ICP-MS). In this work, we describe a rapid way to measure the size distribution of metal-containing particles from 10 nm to 20 μm, using a nano micro-orifice uniform-deposit impactor (nano-MOUDI) to size-selective and collect particles that are then analyzed with a field portable X-ray fluorescence (FP-XRF) to determine metal composition and concentration. The nano-MOUDI was used to sample a stainless-steel aerosol produced by a spark discharge system. The particle-laden substrates were then analyzed directly with FP-XRF and then with ICP-MS. Results from FP-XRF were linearly correlated with results from ICP-MS (R2 = 0.91 for Fe and R2 = 0.84 for Cr). Although the FP-XRF was unable to detect Fe particles at mass per substrate loadings less than 2.5 μg effectively, it produced results similar to those using the ICP-MS at a mass per substrate loading greater than 2.5 μg.

Novel use of field-portable-XRF for the direct analysis of trace elements in marine macroalgae

Samples of dried marine macroalgae (Fucus serratus, Palmaria palmata and Ulva lactuca) have been analysed for trace elements by a novel, non-destructive approach involving a Niton field-portable-X-ray fluorescence (FP-XRF) spectrometer configured in a low density plastics mode with thickness correction. Detection limits for a 200-s counting time ranged from <5 μg g−1 for As and Pb in F. serratus and As in P. palmata to several tens of μg g−1 for Cd, Sb and Sn in all species tested. Arsenic, Cu, Pb and Zn were detected by the XRF in samples collected from a protected beach (n = 18) and in samples therefrom that had been exposed to additional aqueous elements in combination (n = 72) with concentrations returned (in μg g−1) ranging from 3.9 to 39.7 for As, 13.0 to 307 for Cu, 6.1 to 14.7 for Pb and 12.5 to 522 for Zn. Independent measurements of trace elements in the macroalgae by ICP-MS following nitric acid digestion revealed a direct and significant proportionality with concentrations returned by the XRF, with slopes of the XRF-ICP relationships (As = 1.0; Cu = 2.3; Pb = 2.4; Zn = 1.7) that can be used to calibrate the instrument for direct measurements. The approach shows potential for the in situ monitoring of macroalgae in coastal regions that is currently being investigated.

Analysis of the elemental composition of marine litter by field-portable-XRF

Marine litter represents a pervasive environmental problem that poses direct threats to wildlife and habitats. Indirectly, litter can also act as a vehicle for the exposure and bioaccumulation of chemicals that are associated with manufactured or processed solids. In this study, we describe the use of a Niton field-portable-x-ray fluorescence (FP-XRF) spectrometer to determine the content of 17 elements in beached plastics, foams, ropes and painted items. The instrument was used in a ‘plastics’ mode configured for complex, low density materials, and employed a thickness correction algorithm to account for varying sample depth. Accuracy was evaluated by analysing two reference polyethylene discs and was better than 15% for all elements that had been artificially impregnated into the polymer. Regarding the litter samples, limits of detection for a 120s counting time varied between the different material categories and among the elements but were generally lowest for plastics and painted items with median concentrations of less than 10μgg−1 for As, Bi, Br, Cr, Hg, Ni, Pb, Se and Zn. Concentrations returned by the XRF were highly sensitive to the thickness correction applied for certain elements (Ba, Cl, Cr, Cu, Fe, Sb, Ti, Zn) in all matrices tested, indicating that accurate measurement and application of the correct thickness is critical for acquiring reliable results. An independent measure of the elemental content of selected samples by ICP spectrometry following acid digestion returned concentrations that were significantly correlated with those returned by the XRF, and with an overall slope of [XRF]/[ICP]=0.85. Within the FP-XRF operating conditions, Cl, Cr, Fe, Ti and Zn were detected in more than 50% and Hg and Se in less than 1% of the 376 litter samples analysed. Significant from an environmental perspective were concentrations of the hazardous elements, Cd, Br and Pb, that exceeded several thousand μgg−1 in many cases.

Multivariate spatial analyses of the distribution and origin of trace and major elements in soils surrounding a secondary lead smelter.

Major and trace elements in soils originate from natural processes and different anthropogenic activities which are difficult to discriminate. On a 17-ha impacted site in northern France, two industrial sources of soil contamination were xidentified: a former iron foundry and a current secondary lead smelter. To discriminate and map natural and anthropogenic sources of major and trace elements on this site, the rarely applied MULTISPATI-principal component analysis (PCA) method was used. Using a 20-m × 20-m grid, 247 topsoil horizons were sampled and analysed with a field-portable X-ray fluorescence analyser for screening soil contamination. The study site was heavily contaminated with Pb and, to a lesser degree, with Sn. Summary statistics and enrichment factors allowed the differentiation of the main lithogenic or anthropogenic origin of the elements. The MULTISPATI-PCA method, which explained 73.9% of the variability with the three first factors, evidenced strong spatial structures. Those spatial structures were attributed to different natural and artificial processes in the study area. The first axis can be interpreted as a lithogenic effect. Axes 2 and 3 reflect the two different contamination sources. Pb, Sn and S originated from the secondary lead smelter while Fe and Ca were mainly derived from the old iron foundry activity and the old railway built with foundry sand. This study demonstrated that the MULTISPATI-PCA method can be successfully used to investigate multicontaminated sites to discriminate the various sources of contamination.

Can field portable X-ray fluorescence (pXRF) produce high quality data for application in environmental contamination research?

This research evaluates the analytical capabilities of a field portable X-ray fluorescence spectrometer (pXRF) for the measurement of contaminated soil samples using a matrix-matched calibration. The calibrated pXRF generated exceptional data quality from the measurement of ten soil reference materials. Elemental recoveries improved for all 11 elements post-calibration with reduced measurement variation and detection limits in most cases. Measurement repeatability of reference values ranged between 0.2 and 10% relative standard deviation, while the majority (82%) of reference recoveries were between 90 and 110%. Definitive data quality, the highest of the US EPA's three level quality ranking, was achieved for 15 of 19 elemental datasets. Measurement comparability against inductively coupled plasma atomic emission spectrometry (ICP-AES) values was excellent for most elements (e.g, r2 0.999 for Mn and Pb, r2 > 0.995 for Cu, Zn and Cd). Parallel measurement of reference materials revealed ICP-AES and ICP-MS measured Ti and Cr poorly when compared to pXRF. Individual recoveries of soil reference materials by both ICP-AES and pXRF showed that pXRF was equivalent to or better than ICP-AES values for all but two elements (Ni, As). This study demonstrates pXRF as a suitable alternative to ICP-AES analysis in the measurement of Ti, Cr, Mn, Fe, Cu, Zn, Sr, Cd, and Pb in metal-contaminated soils. Where funds are limited, pXRF provides a low-cost, high quality solution to increasing sample density for a more complete geochemical investigation.

Influence of Soil Pore Length upon Portable X-ray Fluorescence Spectrometer Measurements of Elements in Soils

To approximate the measurement accuracy of laborious lab approaches, soil inventories using field portable XRF (pXRF) spectrometers should take distorting parameters into account. Besides soil moisture, the length of water-filled soil pores may also affect X-ray intensity. Following the Arya-Paris approach of soil pore bundles, soil pore lengths were calculated for 20 riparian soil samples based on effective pore diameters obtained at specified pressure heads of the water retention curve. When contrasted against pXRF signals of lead, zirconium, and potassium, soil pore length information showed an explanation comparable to soil moisture values. Presumably, the bases and walls of soil pores are successively exposed to the excitation source during dewatering. Though its laborious determination, soil pore length calculation is based on comparatively static parameters, which may circumvent adverse effects occurring at moisture determination at steel-ring samples, such as artificial macropores in the course of sampling and transport or shrinkage of porosity due to pressure application.

Metal contamination at recreational boatyards linked to the use of antifouling paints-investigation of soil and sediment with a field portable XRF.

The application of a field portable X-ray fluorescence spectrometer (FPXRF) to measure Cu, Zn, and Pb in soil and sediments at recreational boatyards by Lake Mälaren in Sweden was investigated. Confirmatory chemical analysis on freeze-dried samples shows that, ex situ, the FPXRF produces definitive level data for Cu and Zn and quantitative screening data for Pb, according to USEPA criteria for data quality. Good agreement was also found between the ex situ measurements and the in situ screening. At each of the two studied boatyards, >40 in situ soil measurements were carried out. Statistical differences in soil concentration based on land use were consequently found: the areas used for boat storage and maintenance were significantly higher in Cu and Zn than the areas used for car parking and transportation. The metal pollution in the boat storage areas is therefore shown to be directly linked to hull maintenance activities during which metal-containing antifouling paint particles are shed, end up on the ground, and consequently pollute the soil. In the boat storage areas, the Cu and Zn concentrations often exceeded the national guideline values for soil. In this study, they were also shown to increase with increasing age of the boatyard operation. Pb soil concentrations were only elevated at a few measurement points, reflecting the phasing out of Pb compounds from antifouling products over the past 2 decades. In the surface sediments, concentrations of Cu and Zn were 2–3 times higher compared to deeper levels. No decrease in metal concentration with time was found in the sediments, indicating that boat owners are not complying with the ban of biocide-containing paints in freshwater introduced over 20 years ago.

Lead in exterior paints from the urban and suburban environs of Plymouth, south west England

Dry weight concentrations of lead in paints on a variety of structures in the urban and suburban environs of a British city (Plymouth, south west England) were determined in situ and ex situ by field-portable X-ray fluorescence spectrometry. Lead was detected in 221 out of 272 analyses, with overall median and mean concentrations of 4180μgg−1 and 29,300μgg−1, respectively, and a maximum concentration of 390,000μgg−1. Highest concentrations were observed in extant paints on poorly maintained, metallic structures, including railings, gates, telephone kiosks and bridges, in various yellow road line paints, and in paints of varying condition on public playground facilities (ramps, climbing frames, monkey bars). Occupants of households in the vicinity of structures that are shedding leaded paint are at potential risk of exposure from paint particles being tracked in on shoes and clothing while children in contact with leaded paints in playgrounds and recreational areas are at potential risk from the direct ingestion of paint flakes. Since the issues highlighted in the present study are neither likely to be restricted to this city, nor to the UK, a greater, general awareness and understanding of the sources and routes of exposure of exterior leaded paint is called for.

Pre-Mission Input Requirements to Enable Successful Sample Collection by a Remote Field/EVA Team

Pre-Mission Input Requirements to Enable Successful Sample Collection by a Remote Field/EVA Team

Use of a Field-Portable XRF Instrument To Facilitate Metal Catalyst Scavenger Screening

The analysis of elemental impurities in pharmaceuticals has traditionally been performed using plasma-based instrumental techniques, such as inductively coupled plasma-optical emission spectroscopy or inductively coupled plasma-mass spectrometry, due to their inherent sensitivity, selectivity, and precision; however, during development activities, there are a variety of sample types that do not require the sensitivity that these expensive and time-consuming techniques provide. Pharmaceutical process chemists often need a rapid and relative determination of the elemental content to direct them in optimizing the effectiveness or efficiency of their synthetic process. This article will provide the application of a field-portable X-ray fluorescence instrument as a hands-on screening tool for chemists to determine the effectiveness of metal catalyst scavenger studies. Three case studies will be provided to illustrate the usefulness of the technique.

Comparison of field portable XRF and aqua regia/ICPAES soil analysis and evaluation of soil moisture influence on FPXRF results

Purpose Field portable X-ray fluorescence (FPXRF) technology can offer a rapid and cost-effective determination of the total elemental concentrations in soils. The aims of this study were (i) to test the capability of FPXRF to predict the element concentrations of a very large soil sample set and (ii) to assess the influence of soil moisture, known to strongly affect the quality of FPXRF analyses.

Use of a Field Portable X-Ray Fluorescence Analyzer for Environmental Exposure Assessment of a Neighborhood in Cairo, Egypt Adjacent to the Site of a Former Secondary Lead Smelter

The objectives of this study are to demonstrate for the first time the use of a field portable X-Ray Fluorescence Analyzer (XRF) in a multi-media environmental survey and to use the survey results to determine if residual lead from a once-active secondary lead smelter in Cairo, Egypt, still posed a health risk to the residents when comparing results with US EPA standards. Results were analyzed to determine if relationships among the variables indicated that there were residual impacts of the former smelter. Samples collected inside and near a total of 194 dwellings were analyzed. The mean floor dust lead loading was 7.48 μg lead/ft2. Almost 10% of the dwellings had at least one floor dust wipe sample that exceeded the United States Environmental Protection Agency's (USEPA) interior settled dust lead level of 40 μg lead/ft2. The median paint lead level was 0.04 mg lead/cm2. 17% of the dwellings had at least one interior paint sample that exceeded the USEPA standard of 1.0 mg lead/cm2. Mean soil lead concentration in the study area was 458 ppm and 91 ppm outside the study area. Four of nine composite soil samples exceeded the US EPA limit for bare soil in play areas. Lead concentrations in samples collected in locations outside the study area did not exceed the limit. The highest concentration was in the plot closest to the smelter and may represent residual impact from the former smelter. Statistically significant relationships were not detected between interior floor dust lead loading and either interior paint lead loading or exterior dust lead concentration. Thus, no significant exposure from the former smelter was indicated by these analyses. This may have resulted from the time elapsed since the closing of the smelter and/or the relatively low paint lead levels. Further study is needed in other areas of Egypt near former and active lead smelters. Elevated levels of mercury and arsenic detected in soil samples do not appear to be related to the smelter but warrant further study.

Metal concentrations and distribution in paint waste generated during bridge rehabilitation in New York State

Between 1950 and 1980, lead and chromium along with other metals have been used in paint coatings to protect bridges from corrosion. In New York State with 4500 bridges in 11 Regions 2385 of the bridges have been rehabilitated and subsequently repainted after 1989 when commercial use of lead based paint was prohibited. The purpose of this research was to address the concentration and distribution of trace metals in the paint waste generated during bridge rehabilitation. Using hypothesis testing and stratified sampling theory, a representative sample size of 24 bridges from across the state was selected that resulted in 117 paint waste samples. Field portable X-ray fluorescence (FP-XRF) analysis revealed metal concentrations ranged from 5 to 168,090mgkg−1 for Pb, 49,367 to 799,210mgkg−1 for Fe, and 27 to 425,510mgkg−1 for Zn. Eighty percent of the samples exhibited lead concentrations greater than 5000mgkg−1. The elevated iron concentrations may be attributed to the application of steel grit as an abrasive blasting material routinely used by state Departments of Transportation in the paint removal process. Other metals including Ba and Cr were observed in the paint waste as well. As a result of the paint formulation, metals were found to be associated in the paint waste (Pb correlated with Cr (r=0.85)). The elevated metal concentrations observed raises concern over the potential impact of leaching from this waste stream.

Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory analysis

Landfill mining applied in reclamation at the territories of old dump sites and landfills is a known approach tended to global economic and environmental benefits as recovery of metals and energy is an important challenge. The aim of this study was to analyse the concentration of several metallic elements (Ca, Cu, Cr, Fe, K, Mn, Pb, Zn) in the fine fraction of waste derived in the landfill and to compare the results of measurements obtained by field-portable equipment with the data gained by advanced analytical tools. Atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the quantitative detection of metallic elements at the laboratory; whereas field-portable X-ray fluorescence spectrometry (FPXRF) was applied for rapid sample characterisation in the field (on-site). Wet digestion of samples (fine fraction of waste at landfill) was done prior analytical procedures at the laboratory conditions, but FPXRF analysis was performed using raw solid samples of waste fine fraction derived in the Kudjape Landfill in Estonia. Although the use of AAS and ICP-MS for the measurements of metals achieves more precise results, it was concluded that precision and accuracy of the measurements obtained by FPXRF is acceptable for fast approximate evaluation of quantities of metallic elements in fine fraction samples excavated from the waste at landfills. Precision and accuracy of the results provided by express method is acceptable for quick analysis or screening of the concentration of major and trace metallic elements in field projects; however, data correction can be applied by calculating moisture and organic matter content dependent on sample matrix as well as special attention must be paid on sample selection and homogenisation and number of analysed samples.

Evaluation of Field Portable X-Ray Fluorescence Performance for the Analysis of Ni in Soil.

As a rapid, in-situ analysis method, Field portable X-ray fluorescence spectrometry (FP-XRF) can be widely applied in soil heavy metals analysis field. Whereas, some factors may affect FP-XRF performance and restrict the application. Studies have proved that FP-XRF has poorer performance when the concentration of target element is low, and soil moisture and particle size will affect FP-XRF performance. But few studies have been conducted in depth. This study took an example of Ni, demonstrated the relationship between Ni concentration and FP-XRF performance on accuracy and precision, and gave a critical value. Effects of soil moisture and particle size on accuracy and precision also had been compared. Results show that, FP-XRF performance is related to Ni concentration and the critical value is 400 mg x kg(-1). Relative standard deviation (RSD) and relative uncertainty decrease while the Ni concentration is below 400 mg x kg(-1), hence FP-XRF performance improves with increasing Ni concentration in this range; RSD and relative uncertainty change little while the Ni concentration is above 400 mg x kg(-1), hence FP-XRF performance does not have correlation with Ni concentration any more. For in-situ analysis, the relative uncertainty contributed by soil moisture is 3.77%, and the relative certainty contributed by particle size is 0.56%. Effect of soil moisture is evidently more serious than particle size both on accuracy and precision.

The use of FPXRF in the determinations of selected trace elements in historic mining soils in the Holy Cross Mts., south-central Poland

In this study, concentrations of As, Cu, Mn, Pb, and Zn were determined in 231 samples of mine soils and spoils by field portable X-ray fluorescence (FPXRF), and by inductively coupled plasma-mass spectrometry (ICP-MS) as a comparison method. The use of both spectrometric methods allows for comparison of the total and aqua regia -extractable contents of elements. The study areas encompassed three historic metal-ore mining sites and one abandoned mine tailings site in the Holy Cross Mountains, in south-central Poland. Sample collection in these areas, which are characterized by various bedrock mineralogy and lithology and different anthropogenic impacts, enabled us to test the FPXRF performance for a wide range of element concentrations. The results of FPXRF and ICP-MS determinations were found to be significantly correlated with the highest r 2 (coefficient of determination) value of 0.987–0.991 for Pb, irrespective of the soil mineralogy, bedrock lithology or concentration levels of this element. Overall, the FPXRF showed excellent performance in determining selected trace elements in contaminated soils.

Field methods for rapidly characterizing paint waste during bridge rehabilitation

For Department of Transportation (DOT) agencies, bridge rehabilitation involving paint removal results in waste that is often managed as hazardous. Hence, an approach that provides field characterization of the waste classification would be beneficial. In this study, an analysis of variables critical to the leaching process was conducted to develop a predictive tool for waste classification. This approach first involved identifying mechanistic processes that control leaching. Because steel grit is used to remove paint, elevated iron concentrations remain in the paint waste. As such, iron oxide coatings provide an important surface for metal adsorption. The diffuse layer model was invoked (logKMe=4.65 for Pb and logKMe=2.11 for Cr), where 90% of the data were captured within the 95% confidence level. Based on an understanding of mechanistic processes along with principal component analysis (PCA) of data obtained from field-portable X-ray fluorescence (FP-XRF), statistically-based models for leaching from paint waste were developed. Modeling resulted in 96% of the data falling within the 95% confidence level for Pb (R2 0.6–0.9, p⩽0.04), Ba (R2 0.5–0.7, p⩽0.1), and Zn (R2 0.6–0.7, p⩽0.08). However, the regression model obtained for Cr leaching was not significant (R2 0.3–0.5, p⩽0.75). The results of this work may assist DOT agencies with applying a predictive tool in the field that addresses the mobility of trace metals as well as disposal and management of paint waste during bridge rehabilitation.

Metals in boat paint fragments from slipways, repair facilities and abandoned vessels: An evaluation using field portable XRF

Paint flaking off abandoned vessels or generated during boat repair is hazardous to human health and wildlife. In this study, a means of screening paint fragments using a field portable-X-ray fluorescence (FP-XRF) spectrometer is described. The technique is capable of delivering rapid, surficial measurements of Ba, Cu, Pb and Zn down to concentrations less than 150μgg−1, and Sn and Cr to concentrations of a few hundred μgg−1. Application of the technique to fragments collected from slipways, yards, hardstandings, abandoned boats and ships undergoing maintenance throughout the EU reveal highly variable concentrations of metals among samples from the same environment or from the same region of a given boat; in many cases, variability is also evident in different areas or on different surfaces of the same fragment. Of particular concern are elevated concentrations of substances that have been restricted or banned (e.g. Sn, an indicator of organotin, and up to concentrations of 40,000μgg−1, and Pb up to concentrations of 200,000μgg−1). Although FP-XRF can rapidly screen samples whose composition and origin are unknown and can assist in instantaneous decision making, a full risk assessment will rely on additional analyses of the precise species (including organo-forms) of the metals present.

Monitoring changes in salinity and metal concentrations in New Jersey (USA) coastal ecosystems Post-Hurricane Sandy

Temporal changes in pore-water salinity and metal concentrations were investigated in soils from two sites (residential and wetland areas) located in the Old Bridge Township, NJ, after Hurricane Sandy hit the Northeast of the United States of America. Core and surface soil samples were collected in both the residential and wetland sites and then analyzed by field portable X-ray fluorescence (NITON XL3t-600 series FP-XRF). Pore-water salinity was determined from continuous measurements (every 10 min) of conductivity in a single sampling well installed in the wetland site. One month after Hurricane Sandy, pore-salinity was as high as 27 g/L, but gradually decreased to 15 g/L in approximately 3 months. Then, it increased gradually to 26 g/L 3 months later. High metal concentrations (lead, arsenic, copper, chromium, and iron) were measured in the surface and top 2-cm soil layer in both residential and wetland sites, often exceeding background levels within weeks of Hurricane Sandy. These metal contaminations were interpreted as being associated with storm surge from Hurricane Sandy that caused substantial flooding of the coastal areas by large amounts of seawater, loaded with dissolved metal and adsorbed metals to suspended sediments from the Raritan Bay Slag Superfund site. The changes in salinity in wetland areas indicated the intrusion of seawater, thus providing evidence for metal-contaminated seawater altering the wetland’s geochemistry. The transport and deposition of metal contaminants in the coastal areas by Hurricane Sandy increased the risk of human exposure to these contaminants.