What is it?

Portable x-ray fluorescence (pXRF) is a non-destructive geochemical method that uses an x-ray power source to rapidly screen for elemental concentrations, such as lead, arsenic, copper, and zinc. It provides onsite point data collection without the need of data preprocessing of multiple elements. It is also capable of data georeferencing for further spatial analysis and interpretation.

How does it work?

The instrument generates an x-ray beam, and when the beam comes into contact with atoms, electrons detach from lower orbits opening space to electrons from upper orbits to fill the gap. The movement of electrons generates fluorescence energy that the instrument uses to identify the concentration of elements present in the sample.

An advantage of pXRF is the capability of rapid elemental soil screening from phosphorus (P) to lead (Pb) depending on the concentrations and the equipment limit of detection. A limitation of the pXRF technology is that x-ray fluorescence is an elemental technique; therefore, it cannot identify compounds, such as chemicals that have more than one element. Moisture in the soil sample or not evenly mixing the soil sample can affect the results.

How do we use pXRF in soil survey and soil conservation?

NRCS staff have conducted research with applications of pXRF in rapid soil characterization that can be used for more accurate soil classification in the field to more detailed soil mapping. In soil conservation, pXRF has been important in urban agriculture, providing necessary information on soil condition to address resource concerns. Because of the versatility for onsite and easy instrument operation, it is an ideal tool in soil survey and a source of information for conservation planning when visiting landowners on their property.

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