Qualitative evaluation of heavy metals in soils using portable XRF instruments

Portable isotope-source energy dispersive x-ray fluorescence (XRF) analyzers can provide rapid on site screening for heavy metals in soils. Their use generally involves empirical calibration to a suite of representative soil samples spiked with a range of concentrations of the analytes of interest. In most cases, only a limited number of analytes can be measured with this approach, because of constraints imposed by the operational software and costs associated with preparing the calibration suite. A simple approach is described that provides a qualitative indication of anomalous concentrations of heavy metals based on numeric comparison of gross count rates to background values. This approach can rapidly identify contaminated soils and does not depend on a suite of calibration samples. Direct measurements can be made to rapidly map soil contamination without sample collection, and the method can also be applied to other surfaces such as concrete