Field Portable X-ray Fluorescence Research Articles

Hazardous Elements in Road Dust from Petrol Stations in Rzeszów (Podkarpackie, Poland): Toxicological Assessment Using Field Portable X-ray Fluorescence (FP-XRF) as ‘White Analytical Technique’

AbstractSamples of road dust (RD) from petrol stations (n = 20) located in Rzeszów (Podkarpackie, Poland) were analysed to find potential markers of traffic-related pollution. The level (μg/g) of: Mo, U, As, Hg, Th, Pb, Ni, Cu, Cr, Be, Sr, Zr, Zn, Mn and Fe were measured using field portable X-ray spectroscopy (FP-XRF) as a direct, rapid and ‘white analytical technique’. Our research demonstrated for the first time the utility of using FP-XRF for environmental toxicological assessment of RD from petrol stations. The qualitative and quantitative composition of the dust samples tested provides valuable research material for creating and updating regulations and finding pollution hotspots such as petrol stations. It was possible to find potential markers of traffic-related pollution (e.g., Zr and Fe forms of disk brakes or brake pads). Certain elements of the study give ambiguous signals related to fuel distribution and road traffic. They can come from various sources of environmental contamination. The adoption of evidence-based policies to minimise pollution, conserve the environment, and protect the well-being of people living or working near gas stations is anticipated to be aided by these findings for policymakers, regulatory authorities, and stakeholders. Incorporating toxicological risk assessment framework, this study pioneers the investigation of human exposure to hazardous elements in RD, an in-depth evaluation of both carcinogenic and non-carcinogenic health risks associated with such exposure including lifetime average daily dose. Our findings contribute novel insights into the environmental toxicology of urban areas, emphasising the need for tailored interventions to mitigate these risks.

Hazardous elements in plastic and rubber granules as infill material from sports facilities? Field Portable-XRF spectroscopy as ‘white analytical technique’ reveals hazardous elements in fall sports facilities in Rzeszów (Podkarpackie, Poland)

Plastic and rubber granules are commonly used as infill material in all-weather sports facilities, providing an ideal activity surface for millions of Europeans on a daily basis. However, concerns have been raised about the presence of hazardous elements in these granules, which can pose risks both to the environment and human health. Our study focusses on the elemental composition of rubber granules used in fall sports facilities in Rzeszów, (Podkarpackie, Poland) using field portable X-ray fluorescence (FP-XRF) as a non-destructive and ‘white analytical technique’. The results show the content of Zn, Fe, Cr, Ba, Br, Ti, Cu, Cd, As, Au, Bi, Pb, Ni, Sb, and Sn in the rubber granule samples. This study highlights the need for stringent quality control measures and regulations to ensure the safety of all-weather sports facilities and protect the well-being of sportsman. When modern FP-XRF spectrometry is employed as a “white analytical technique,” for the first time it becomes possible to identify the presence of hazardous elements, addressing the pressing concerns highlighted by the ECHA and enabling proactive measures to mitigate potential risks. This approach ensures the protection of the health and sustainability of sports facilities, contributing to the ongoing hot topics in the field.

Laboratory comparison of field portable X-ray fluorescence spectrometer (FP-XRF) and inductively coupled plasma mass spectrometry (ICP-MS) for determination of airborne metals in stainless steel welding fume

Welding fume is a common exposure in occupational settings. Gravimetric analysis for total particulate matter is common; however, the cost of laboratory analyses limits the availability of quantitative exposure assessment for welding fume metal constituents in occupational settings. We investigated whether a field portable X-ray fluorescence spectrometer (FP-XRF) could provide accurate estimates of personal exposures to metals common in welding fume (chromium, copper, manganese, nickel, vanadium, and zinc). The FP-XRF requires less training and is easier to deploy in many settings than traditional wet laboratory analyses. Filters were analyzed both by FP-XRF and inductively coupled plasma mass spectrometry (ICP-MS). We estimated the FP-XRF limit of detection for each metal and developed a correction factor accounting for the non-uniform deposition pattern on filter samples collected with an Institute of Medicine (IOM) inhalable particulate matter sampler. Strong linear correlation was observed for all metals (0.72<r < 0.96). The median percent bias for chromium and nickel was less than 15%. The linear slope between the two methods for some metals (copper, manganese, and zinc) was greater than 1, indicating that the FP-XRF overestimated metal mass (median percent bias for vanadium was the largest at 94%), but the linearity of the response suggests that appropriate correction factors could be developed.

Lead exposure in childhood and historical land use: a geostatistical analysis of soil lead concentrations in South Philadelphia parks.

Elevated soil lead (Pb) concentrations in public parks and outdoor spaces continue to have a significant impact on the public health of urban communities. This study evaluated the geospatial and statistical relationships between soil Pb concentrations, the urban environment, and child blood lead levels (BLLs) in the neighborhood of South Philadelphia, PA. Soil samples (n = 240) were collected from forty (40) public parks and analyzed for Pb using a field portable X-ray fluorescence (XRF) analyzer. Geospatial mapping was used to investigate historical land use of each park, vehicular traffic on adjacent roadways, and density of residential/commercial development. Predicted child BLLs and BLL "high-risk areas" were identified using interpolation and biokinetic modeling. Childhood BLL data for South Philadelphia (n = 10,379) was provided by the Philadelphia Department of Public Health (2013-2015). Of the two hundred forty (240) soil samples collected, Pb levels for 10.8% of samples were ≥ 400ppm. Two hundred sixty-nine of 10,379 children screened were identified with BLLs ≥ 5µg/dL. Historical land use of each park was shown to be significantly correlated (p = 0.01) with soil Pb concentrations and child BLLs ≥ 5µg/dL. Approximately 13.3% of the variance in child BLLs ≥ 5µg/dL was attributed to historical site land use. Overall, undeveloped/greenspace historical land use exhibited the highest soil Pb concentrations in the study. Geospatial relationships were identified between census tracts with higher percentages of children with BLLs ≥ 5µg/dL and interpolated BLL "high-risk" areas (≥ 3.5µg/dL). The results of this study suggest soil accumulation time and historical land use may influence soil Pb concentrations and child BLLs in urban communities. Measured soil Pb concentrations were determined to effectively model community-wide contamination and childhood Pb exposure.

Qualitative comparison of elemental concentration in soils and other geomaterials using FP-XRF.

Field portable X-ray fluorescence (FP-XRF) has tremendous potential in geoenvironmental engineering as a qualitative assessment tool. Identification of the elevated concentrations of the selected elements (Cr, Cu, Mn, Ni, Pb, and Zn) in various geomaterials like soil-like-material (SLM), incinerated bottom ash (IBA), construction and demolition waste (CDW), zinc tailings (ZT) and fly ash (FA) was performed by FP-XRF and compared with the local soil–Delhi silt. Comparably higher concentrations (mg/kg) of Cr (401.0), Cu (499.0), Pb (532.0), Zn (608.0) in SLM, Cr (195.0), Cu (419.0), Ni (93.0), Pb (931.0), Zn (771.0) in IBA and Cr (195.0), Cu (4000.0), Pb (671.0), Zn (7122.0) in ZT were observed. CDW and FA showed similar concentrations range as in local soils. FP-XRF was also used in-situ on local soil at 11 sites to examine its ability to identify the elements with significant variations in concentrations. The results showed high variability in Cl and S concentration values across the 11 sites attributed to the changing moisture content and dissolved salts. The concentration range for the remaining elements were similar at all sites. The verification of the detected elements through visual inspection of the spectrum was also carried out.

Challenges in Interpreting Geochemical Data: An Appraisal of Analytical Techniques Applied to a Karstic Lake Sediment Record

The paleoclimatic and paleoenvironmental changes inferred from shifts in lake sediment geochemistry require reliable, efficient and cost-effective methods of analysis. The available geochemical techniques, however, suggest that different analytical approaches can influence data interpretation. X-ray fluorescence core scanner analyses (XRF-CS), field portable X-ray fluorescence (FPXRF) and inductively coupled plasma optical emission spectrometry (ICP-OES) were concurrently applied to provide a multi-method geochemical appraisal of a 6000-year-long karstic sediment record (Lake Ighiel, Romania). The comparison between techniques was based on a set of elements that are widely employed in environmental reconstructions (Ti, K, Fe, Ca). Descriptive and statistical approaches were used to assess the advantages and disadvantages of each method and assess their optimal use in karstic environments. Our data display similar downcore patterns, with strong to moderate correlations between the datasets. The discrepancies observed between method-specific downcore multi element behaviour are related to the preparation steps and sampling. To best capture the complexity of past environmental changes in karstic settings, a combination of quantitative and qualitative geochemical methods would be the most appropriate approach to reliable data acquisition and subsequent paleoenvironmental interpretation of lake sediment data.

Smart Determination of Gold Content in PCBs of Waste Mobile Phones by Coupling of XRF and AAS Techniques

Quantitative determination of most economic valuable metals in waste is the first fundamental operation of evaluating the feasibility of recycling processes. Field-portable X-ray fluorescence spectrometers (FPXRFs) represent a more practical, efficient, and economic tool in determining the elemental composition of samples with respect to conventional analytical techniques, such as atomic absorption spectrometry (AAS) and inductively coupled plasma emission spectrometry (ICP). In this paper, quick and smart determination of gold content in printed circuit boards (PCBs) of waste mobile phones was studied. The aim of the research was to combine the practicality of FPXRFs with the reliability of quantitative spectrometry analysis and evaluate the error between the two techniques. Several samples (33) of PCBs were ground to a size below 0.5 mm, and then, the powders were analyzed by FPXRFs at different acquisition times with five replications for each sample. The same analyzed samples then underwent chemical attack to determine the quantitative gold content by AAS. The obtained results were associated with FPXRFs response with the purpose of realizing a calibration curve (100–1000 mg/kg Au). The curve was validated for accuracy and precision by other PCBs waste samples; the control samples were added as standards to obtain a more reliable calibration curve. The curve was evaluated with RPD classification, regression linear, and Bolt–Altman analysis.

A comparison of XRFS and ICP-OES methods for soil trace metal analyses in a mining impacted agricultural watershed.

Field portable X-ray fluorescence spectroscopy (XRFS) has become increasingly prevalent for in situ detection of trace metals, as it is both rapid and cost effective. The accuracy of in situ XRFS analyses has been questioned due to possible interferences from elevated soil moisture and organic content. In this study, three metal analysis protocols (Cd, Pb, Zn) were compared for surface soil samples collected near the Tar Creek Superfund Site in northeastern Oklahoma. The protocols included the use of a field portable XRF spectrometer for in situ analyses and on homogenized, pulverized, air-dried soil samples sieved to < 250-µm fraction in the laboratory. A subset of soil samples was also analyzed after microwave-assisted hot HNO3 digestion followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) analyses. Moisture content and loss-on-ignition (as a surrogate for organic matter) were determined for each sample. Soil moisture exceeding 10% in situ caused underreporting of field XRF readings when compared to the laboratory XRF readings. Relationships between concentrations determined by laboratory XRFS and ICP-OES for Pb (r2 = 0.96) and Zn (r2 = 0.91) were not statistically different (p < 0.025 for both analytes). A strong relationship between ICP-OES analyses of Zn and Cd (r2 = 0.93) allowed prediction of Cd concentrations for additional samples not analyzed by ICP-OES. This study recommends that XRFS field readings be used for initial screening only and that samples analyzed via field portable XRFS be homogenized, air dried, sieved and re-analyzed in the laboratory to yield the most accurate results.

Home-based informal jewelry production increases exposure of working families to cadmium

Trace element concentrations in biological fluids may vary according to the individual exposome, especially when considering specific external factors of the environment, such as occupational activities. The aim of this study was to determine concentrations of Potentially Toxic Elements (PTEs: As, Cr, Cd, Cu, Mn, Ni, Pb, Zn) in urine samples of informal jewelry workers and in jewelry and soldering powder. Fifty-two families from Brazil comprised the Exposed (n = 113) and Control (n = 79) groups. PTE concentrations in urine samples (n = 192) of workers, controls and their family members were determined by ICP-MS. Soldering powder samples (n = 7) and jewelry pieces (n = 54) were measured for PTEs by field-portable X-ray fluorescence. Levels of PTEs in urine and occupational exposure associations were determined. The environment-wide association study (EWAS) approach was applied to test the influence of occupational activities on participant exposure. Mean PTE concentrations were within the limits recommended in urine by Brazilian occupational guidelines. However, As, Cd, Ni and Zn concentrations in some samples exceeded acceptable values for environmental exposure in the U.S and Canada, as well as Brazilian occupational limits. Cd concentrations were higher for women (0.19 μg g−1 creatinine; p = 0.01), adult workers (0.25 μg g−1 creatinine; p = 0.0002) and smokers (0.27 μg g−1creatinine; p = 0.0001). The difference between the Exposed (0.17 μg g−1creat.) and Control groups (0.10 μg g−1creat.) for Cd was significant among non-smokers. Workers engaged in soldering and assemblers had higher Cd concentrations (0.61 and 0.18 μg g−1 creatinine, respectively) than individuals not working with jewelry production (0.12 μg g−1 creat). PTEs in some jewelry and all soldering powder exceeded Brazilian limits. Considering this exposure scenario, informal jewelry production increased urinary cadmium levels in workers. Occupational exposure to this element in the household environment should be explored, as it may pose a health risk to family members and workers alike.

Field Portable X-Ray Fluorescence (pXRF) Spectrometry for Chemical Dust Source Characterization: Investigations of Natural and Mining-Related Dust Sources in Greenland (Kangerlussuaq Area)

In this study, we evaluate the use of field portable X-ray fluorescence (pXRF) as a screening tool for dust source characterisation at two sites in Greenland, a natural site near Kangerlussuaq influenced by dust generated by the Greenland Ice Sheet and an anorthosite mine site located 80 km from Kangerlussuaq. Measurements of ground surface samples were done ex-situ in LDPE plastic bags and in-situ at selected locations. Ex-situ measurements were done both before and after drying of samples to evaluate the effect of water content. Further, the effect of XRF cup films and LDPE bag walls was measured to enable element-specific corrections for signal attenuation of the pXRF measurements. Accuracy and precision were evaluated using a matrix blank and three different soil certified reference materials (CRMs). Finally, pXRF data from the two sites were analysed statistically by principal component analysis (PCA) and linear discriminant analysis (LDA) for the purpose of discriminating between dust sources. The pXRF results showed detectable concentrations of the elements: Al, Si, K, Ca, Fe, Sr, Zr and Ba in all samples (and P, Mn, Zn, Rb, Y, Nb, Ta, Pb and Th in some samples). Moreover, the results showed good accuracies for 21 elements in the CRMs. The PCA/LDA plots based on the pXRF data provided a good tool to discriminate between natural and mining-related dust sources and also between some specific mining-related sources. Altogether, this demonstrates that pXRF combined with multivariate statistics can be an adequate tool for fast cost-effective dust source characterisation.

Use of field-portable XRF in exploration of PGE-enriched zones in the Pilanesberg PGE deposit, Bushveld Complex, South Africa

The field-portable X-ray fluorescence (FPXRF) spectrometer has evolved significantly in the last decade and has become one of the most innovative tools for field geologists. Portability and ease of use of FPXRF systems have opened up new and unique applications for even novice technicians. Application of FPXRF in precious metals exploration and mining appears to be challenging due to their low concentrations (lower than detection limit by FPXRF) in nature and even in most ore deposits. This case study shows the success of FPXRF in identifying anomalous zones of platinum group elements (PGE) and Au (target elements) using pathfinder elements in the Pilanesberg PGE deposit, Bushveld Complex, South Africa. Sixty-three core samples were analysed using both FPXRF and laboratory methods. In these samples, Pt &lt;8 ppm, Pd &lt;5 ppm and Au &lt;1 ppm, which were not detected by FPXRF; however, Ni and Cu are up to 6540 and 3560 ppm, respectively, which were easily detected by the same method. These elements show positive correlation with the precious metals indicating that they can be used as pathfinders. Both direct shot analyses of core samples and their pulverized specimen assays show correlation with lab assay data suggesting that both methods can be used in the field; however, the accuracy of direct shot data is lower due to the heterogeneity of samples.

Resampling with in situ field portable X-ray fluorescence spectrometry (FPXRF) to reduce the uncertainty in delineating the remediation area of soil heavy metals.

There must be some uncertainty in the remediation areas delineated based on limited sample points, and resampling in the high-uncertainty areas is particularly necessary. In situ field portable X-ray fluorescence spectrometry (FPXRF), a rapid and cheap analysis method for soil heavy metals, is strongly affected by many spatially non-stationary soil factors. This study first delineated the high-uncertainty area (threshold-exceeding probabilities (PTE) between 30% and 70%) of soil Pb based on the 1000 realizations produced by sequential Gaussian simulation (SGS) with 93 ICP-MS Pb concentrations measured in a peri-urban agriculture area, China. Next, in situ FPXRF was used to increase sample density in this high-uncertainty area. Then, robust geographically weighted regression (RGWR) was used to correct the in situ FPXRF Pb, and the correction accuracies of RGWR, basic GWR, and traditionally-used ordinary least squares regression (OLSR) were compared. Finally, to explore the best way to combine these corrected in situ FPXRF concentrations in delineating the remediation area, we compared the following spatial simulation methods: basic SGS, sequential Gaussian co-simulation (CoSGS) with the RGWR-corrected in situ FPXRF Pb as auxiliary soft data (CoSGS-CorFPXRF), and SGS with the RGWR-corrected in situ FPXRF Pb as part of hard data (SGS-CorFPXRF). Results showed that (i) RGWR produced higher correction accuracy (RI=71.5%) than GWR (RI=59.68%) and OLSR (RI=25.58%) for the in situ FPXRF Pb; (ii) SGS-CorFPXRF produced less uncertainty (G=0.97) than CoSGS-CorFPXRF (G=0.95) and SGS (G=0.91) in the spatial simulation; (iii) High-uncertainty area (30%<PTE<70%) was reduced from 36.55% to 8.7% of the whole study area. It is concluded that the recommended methods are cost-effective to reduce the uncertainty in delineating the remediation areas of soil heavy metals.

Source apportionment of soil heavy metals using robust spatial receptor model with categorical land-use types and RGWR-corrected in-situ FPXRF data.

High-density samples are usually a prerequisite for obtaining high-precision source apportionment results in large-scale areas. In-situ field portable X-ray fluorescence spectrometry (FPXRF) is a fast and cheap way to increase the sample size of soil heavy metals (HMs). Moreover, categorical land-use types may be closely associated with source contributions. However, the above information has rarely been incorporated into the source apportionment. In this study, robust geographically weighted regression (RGWR) was first used to correct the spatially varying effect of the related soil factors (e.g., soil water and soil organic matter) on in-situ FPXRF in an urban-rural fringe of Wuhan City, China, and the correction accuracy of RGWR was compared with those of the traditionally non-spatial multiple linear regression (MLR) and basic GWR. Then, the effect of land-use types on HM concentrations was partitioned using analysis of variance (ANOVA). Last, based on the robust spatial receptor model (i.e., robust absolute principal component scores/RGWR [RAPCS/RGWR]), this study proposed RAPCS/RGWR with categorical land-use types and RGWR-corrected in-situ FPXRF data (RAPCS/RGWR_LU&FPXRF), and its performance was compared with those of RAPCS/RGWR with none or one kind of auxiliary data. Results showed that (i) the performances of the correction models for in-situ FPXRF data were in the order of RGWR>GWR>MLR, and the relative improvement of RGWR over MLR ranged from 52.6% to 70.71% for each HM; (ii) categorical land-use types significantly affected the concentrations of soil Zn, Cu, As, and Pb; (iii) the highest estimation accuracy for source contributions was obtained by RAPCS/RGWR_LU&FPXRF, and the lowest estimation accuracy was obtained by basic RAPCS/RGWR. It is concluded that land-use types and RGWR-corrected in-situ FPXRF data are closely associated with the source contribution, and RAPCS/RGWR_LU&FPXRF is a cost-effective source apportionment method for soil HMs in large-scale areas.

Distribution of heavy metals in soils from abandoned dump sites in Kumasi, Ghana

This study investigated the heavy metal content and the extent of pollution in soils from abandoned dump sites in Kumasi, Ghana. Concentrations of heavy metals in the 70 soil samples were determined using a Niton XL3t GOLD field portable X-ray fluorescence spectrometer and confirmed on an Agilent 7800 inductively coupled plasma-mass spectrometer. Mercury was determined with a Lumex mercury analyzer. Mean concentrations of metals in soils were in the order: Zn (166 mg/kg). Cr (67 mg/kg) > Cu (32 mg/kg), Ni (22 mg/kg) > Pb (11 mg/kg) Cd (8.9 mg/kg) > As (4.2 mg/kg) > Hg (0.04 mg/kg) for Kronum; and Zn (558 mg/kg), Cu (347 mg/kg), Pb (288 mg/kg) > Cr (77 mg/kg) > Ni (35 mg/kg) > As (11 mg/kg) > Cd (3.0 mg/kg) > Hg (0.19 mg/kg) for Amakom. Pollution indices (geo-accumulation, contamination factor, pollution load and potential ecological risk) indicated very high contamination for arsenic, cadmium and lead at Kronum and arsenic, cadmium, copper, lead and zinc at Amakom. Mercury recorded the least level of pollution for both dump sites. Regular monitoring of these abandoned dump sites is required. Remediation programs in these sites should also be instituted.

Accumulation and bioaccessibility of toxic metals in root tubers and soils from gold mining and farming communities in the Ashanti region of Ghana

ABSTRACT The presence of metal contaminants in agricultural soils and subsequent uptake by food crops can pose serious human health risk. In this study, we assessed the levels of toxic metals – arsenic, chromium, copper, iron, manganese, nickel, and zinc – in soils and some edible root tuber crops from two gold mining and two non-mining communities in Ghana to evaluate the potential human health risks associated with exposure to these metals. Concentrations of the metals in 154 soil and edible root tuber samples were analyzed using field portable x-ray fluorescence spectrometer prior to confirmation by inductively coupled plasma mass spectrometry. Bioaccessibility of the metals was determined using an in vitro physiologically based extraction technique. Concentrations of the metals were generally higher in the gold mining communities than in the non-mining communities. The contamination indices indicated low to moderate contamination of the soil and food crops. Bioaccessibility for the metals varied from 1.7% (Fe) to 62.3 (Mn). Overall, the risks posed by the metals upon consumption of the tubers were low.

Towards Multiscale and Multisource Remote Sensing Mineral Exploration Using RPAS: A Case study in the Lofdal Carbonatite-Hosted REE Deposit, Namibia

Traditional exploration techniques usually rely on extensive field work supported by geophysical ground surveying. However, this approach can be limited by several factors such as field accessibility, financial cost, area size, climate, and public disapproval. We recommend the use of multiscale hyperspectral remote sensing to mitigate the disadvantages of traditional exploration techniques. The proposed workflow analyzes a possible target at different levels of spatial detail. This method is particularly beneficial in inaccessible and remote areas with little infrastructure, because it allows for a systematic, dense and generally noninvasive surveying. After a satellite regional reconnaissance, a target is characterized in more detail by plane-based hyperspectral mapping. Subsequently, Remotely Piloted Aircraft System (RPAS)-mounted hyperspectral sensors are deployed on selected regions of interest to provide a higher level of spatial detail. All hyperspectral data are corrected for radiometric and geometric distortions. End-member modeling and classification techniques are used for rapid and accurate lithological mapping. Validation is performed via field spectroscopy and portable XRF as well as laboratory geochemical and spectral analyses. The resulting spectral data products quickly provide relevant information on outcropping lithologies for the field teams. We show that the multiscale approach allows defining the promising areas that are further refined using RPAS-based hyperspectral imaging. We further argue that the addition of RPAS-based hyperspectral data can improve the detail of field mapping in mineral exploration, by bridging the resolution gap between airplane- and ground-based data. RPAS-based measurements can supplement and direct geological observation rapidly in the field and therefore allow better integration with in situ ground investigations. We demonstrate the efficiency of the proposed approach at the Lofdal Carbonatite Complex in Namibia, which has been previously subjected to rare earth elements exploration. The deposit is located in a remote environment and characterized by difficult terrain which limits ground surveys.

Advances in exploration geochemistry, 2007 to 2017 and beyond

Mineral exploration under relatively young, exotic cover still presents a major challenge to discovery. Advances and future developments can be categorized in four key areas, (1) understanding metal mobility and mechanisms, (2) rapid geochemical analyses, (3) data access, integration and interoperability and (4) innovation in laboratory-based methods. Application of ‘regolith-style9 surface mapping in covered terrains outside of conventional lateritic terrains is achieving success in terms of reducing background noise and improving geochemical contrasts. However, process models for anomaly generation are still uncertain and require further research. The interaction between the surface environment, microbes, hydrocarbons and chemistry is receiving greater attention. While significant progress has been achieved in understanding the role of vegetation, interaction with the water table and cycling of metals in the near surface environment in Australia, other regions of the world, for example, the till-covered terrains in the northern hemisphere and arid colluvium-covered areas of South America, have seen less progress. In addition to vegetation, the influence of bacteria, fungi and invertebrates is not as well studied with respect to metal mobilization in cover. Field portable XRF has become a standard field technique, though more often used in a camp setting. Apart from a tweaking of analytical quality, instruments have probably reached their peak of analytical development with add-ons, such as cameras, beam-limiters, wireless transmission and GPS as the main differences between instrument suppliers. Their future rests in automated application in unconventional configurations, for example, core scanning and better integration of analytical data with other information such as spectral analyses. Pattern drilling that persists in industry, however, has benefited from innovative application of field-portable tools along with rock and mineral chemistry to provide near real-time results and assist in a shift toward more flexible and targeted drilling in greenfields settings. Innovation in the laboratory continues to progress. More selective geochemical analysis, imaging of fine particle size fractions and resistate mineral phases and isotope analysis are faster and more accessible than ever before. The application of genomics (and data analysis) as mineral exploration tools is on the horizon. A continuing problem in geoscience, the supply to industry of suitably trained geochemists, persists although some needs, particularly at junior level, will be met by recent initiatives at various universities at graduate level. Unfortunately, the current economic climate has had a significant impact on R&D and retention of geochemistry skills by the industry. Whilst the future is positive, significant investment is required to develop the next generation of geochemical exploration tools and concepts. Thematic collection: This article is part of the Exploration 17 collection available at: https://www.lyellcollection.org/cc/exploration-17

Size, composition, morphology, and health implications of airborne incidental metal-containing nanoparticles

There is great concern regarding the adverse health implications of engineered nanoparticles. However, there are many circumstances where the production of incidental nanoparticles, i.e., nanoparticles unintentionally generated as a side product of some anthropogenic process, is of even greater concern. In this study, metal-based incidental nanoparticles were measured in two occupational settings: a machining center and a foundry. On-site characterization of substrate-deposited incidental nanoparticles using a field-portable X-ray fluorescence provided some insights into the chemical characteristics of these metal-containing particles. The same substrates were then used to carry out further off-site analysis including single-particle analysis using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Between the two sites, there were similarities in the size and composition of the incidental nanoparticles as well as in the agglomeration and coagulation behavior of nanoparticles. In particular, incidental nanoparticles were identified in two forms: submicrometer fractal-like agglomerates from activities such as welding and supermicrometer particles with incidental nanoparticles coagulated to their surface, herein referenced as nanoparticle collectors. These agglomerates will affect deposition and transport inside the respiratory system of the respirable incidental nanoparticles and the corresponding health implications. The studies of incidental nanoparticles generated in occupational settings lay the groundwork on which occupational health and safety protocols should be built.

Evaluating the utility of elemental measurements obtained from factory-calibrated field-portable X-Ray fluorescence units for aquatic sediments

We assessed factory-calibrated field-portable X-ray fluorescence (pXRF) data quality for use with minimally-prepared aquatic sediments, including the precision of replicate pXRF measurements, accuracy of factory-calibrated pXRF values as compared to total digestion/ICP-OES concentrations, and comparability of calibrated pXRF values to extractable concentrations. Data quality levels for precision, accuracy, and comparability were not equivalent for element/analyzer combinations. All analyses of elements that were assessed for precision and accuracy on a single analyzer were both precise (<10% relative standard deviation) and accurate (r2 > 0.85) for K, Ca, Ti, Mn, Fe, and Zn. Calibrated pXRF values for Al, K, Ca, Ti, Mn, Fe, Cu, Zn, and Pb were within ∼10% relative difference of total digestion/ICP-OES concentrations. Calibrated pXRF values for Fe, Cu, Zn, As, and Pb were within ∼20% relative difference of extractable concentrations. Some elements had a higher level of data quality using specific analyzers, but in general, no pXRF analyzer had the highest level of data quality in all categories. Collectively, our data indicate that a wide range of factory-calibrated pXRF units are capable of providing high-quality total concentrations for the analysis of aquatic sediments.

Biogeochemical mapping of metal contamination from mine tailings using field-portable XRF

Trace and major element composition of selected plant species and parts may be used to map geochemical dispersion from mineral deposits and contaminated areas. This study examines the application of field-portable X-ray fluorescence spectrometry (fpXRF) in obtaining real-time biogeochemical data. In situ analysis of parts of black and silver wattle (Acacia mearnsii De Wild. and Acacia dealbata Link) was conducted to map the extent of contamination surrounding the former Woodlawn base metal mine. High levels of ore-related elements were detected in the bark of these species in a zone extending up to 1 km down-drainage from the tailing ponds. Major elements are more elevated in bark on the side of the trees facing the tailings ponds and correlations between trace and major elements indicate dust contamination. The penetration distance for X-rays is dependent on the energy of the secondary X-rays measured, with the maximum depth of penetration in bark and leaf material <30 mm. There was a close correlation for most elements between the fpXRF and laboratory-based XRF analysis but with element-dependent attenuation by the organic matrix. Providing there is consistency in sampling and analytical methodology, in situ fpXRF analysis of vegetation is an effective method in both contamination surveys and biogeochemical mineral exploration for a range of trace and major elements.