How to Detect Arsenic In Soil with XRF
Arsenic is a naturally occurring element in a lot of soil types, which makes arsenic site investigation more complicated than investigations for other contaminants.
The question isn't always whether or not arsenic is in the soil, but whether or not the concentration exceeds background levels and cleanup thresholds.
Anthropogenic arsenic sources include pesticide application on orchards and agricultural land. Particularly sites with historical use of lead arsenate and calcium arsenate pesticides.
Wood treatment facilities using chromated copper arsenate (CCA) are another significant source.
Smelter operations, mining sites, and coal combustion all deposit arsenic in surrounding soils. Naturally elevated background concentrations complicate cleanup threshold determinations in geologically sensitive areas.
XRF is the best way to detect arsenic in soil at concentrations above approximately 10 to 20 mg/kg, depending on the soil matrix and measurement conditions.
Where XRF delivers practical value in arsenic investigations is at sites where concentrations are significantly elevated above background, like former orchard sites, wood treatment facilities, and smelter-impacted properties. These are all places where the decision being made is about spatial extent and hot spot identification instead of borderline threshold determinations.
Scanning a former orchard grid with XRF identifies which sampling locations have elevated arsenic and which are at background levels. That information directs laboratory sampling toward the high-concentration areas and reduces the number of clean-area samples that consume laboratory budget without informing remediation decisions.
Arsenic and lead frequently appear together at sites with histories of pesticide use, given the historical prevalence of lead arsenate in pesticide.
XRF analysis captures both at the same time, and that's a practical advantage over single-element screening methods.
Screen arsenic-impacted sites efficiently before committing your full laboratory budget.
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More XRF Resources for Soil Testing
There are a lot of ways to save money and time with XRF analysis, especially in industries that need perform soil testing. Learn more about the uses and benefits of XRF analysis for your business from an XRF professional.