Portable X-Ray Fluorescence as a Rapid Technique for Surveying Elemental Distributions in Soil

Abstract

Case studies from two sites demonstrate how concentration distributions of hazardous contaminants can be rapidly measured and visualized using portable XRF (X-ray fluorescence) coupled with geostatistical interpolation tools. In this study, lead is used as an exemplar due to its well-known detrimental effect on human health through long-term exposure. A portable Thermo Scientific NITON X-ray fluorescence (XRF) instrument was used for real-time in-situ concentration measurements, which were linked to GPS coordinates of the sampling locations. A 52 point mixed sampling density survey was performed at a site near Maynooth, Co. Kildare, and a second 58 survey undertaken at Dublin City University (DCU). At Maynooth, high concentrations of Pb (above 110 mg=kg) were found close to the site where a local canal meets a road. At the DCU site, results indicate high Pb concentrations (above 160 mg=kg) near a busy main road. Geostatistical techniques were used to generate concentration prediction and critical threshold contour surfaces for both sites. Linked with GPS coordinates for each sampling location, this technology enables the distribution of multiple elements to be mapped over wide areas in a relatively short time.

Potential of integrated field spectroscopy and spatial analysis for enhanced assessment of soil contamination: A prospective review

“…In this regard, some official methodologies now recognise PXRF technology for use in in-situ measurement of soil contaminants such as the United States Environmental Protection Agency (US EPA) Method 6200 which in turn also recognises the instrument's internal factory-installed calibrations for elemental detection (Radu et al, 2013;Weindorf et al, 2014). Furthermore, the latest USDA-NRCS soil survey and laboratory method manual now also includes a referenced method for PXRF use (USDA-NRCS, 2014).…”

“…PXRF devices have also been used successfully for in-field environmental screening to detect the occurrence of elevated concentrations of metals in the soil (Carr et al, 2008;Fujimori and Takigami, 2014;Kalnicky and Singhvi, 2001;Radu et al, 2013;Weindorf et al, 2013b). For example, Weindorf et al (2013b) used a PXRF spectrometer to survey a site in Zlatna, Romania, with a history of mining/smelting operations.…”

“…The authors concluded that the use of georeferenced PXRF data offers a powerful tool for the in-situ assessment and areal identification of contaminated soil. Similarly, Radu et al (2013) successfully mapped the distribution of the main anthropogenic metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, V and Zn) at two sites in Ireland. Fujimori and Takigami (2014) investigated the distribution of heavy metals (Pb, Cu, Zn) in surface soils at an electronic waste recycling workshop in Manila, Philippines.…”

Moving your laboratories to the field – Advantages and limitations of the use of field portable instruments in environmental sample analysis

“…On-site screening is useful for creation of spatial contaminant distribution maps. Visualization of data from on-site measurements can be done in the field as demonstrated by two case studies on lead distribution in soil carried out by Radu et al (2013).…”

Sensing and Sensor Fundamentals

“…A key advantage of the technique is that it requires almost no sample preparation, such as acid digestion. However, the technique is limited to bulk concentration analysis in which high concentrations of an element are likely to be present in a sample (Radu, et al, 2013). Other commonly used instruments include temperature and moisture meters and penetrometer for the measurement of soil strength.…”