Assessing Anthropogenic Soil Changes Via Portable x-Ray Fluorescence Spectrometry.

Portable x-ray fluorescence (PXRF) spectrometry is a rapid, proximal sensing technique capable of providing quantitative elemental data in-situ. The technology has previously been used extensively for geological, metallurgical, and environmental assessment applications. Originally developed as a large laboratory-based instrument, recent advances have made the instrument not only portable, but handheld. The US Environmental Protection Agency is among many agencies and scientists who have endorsed PXRF’s application to soil and sediments (EPA Method 6200). Adoption of other field portable, proximal sensing systems (ground penetrating radar, visible near infrared diffuse reflectance spectroscopy) by field soil scientists has become popular given substantial savings in sample analysis, rapid data acquisition, and high accuracy of results. Over the past 5 years, a research team at the Louisiana State University Agricultural Center has worked to evaluate a number of different soil science applications for PXRF. Among them are studies utilizing PXRF for: 1) assessment of heavy metal spatial variability in peri-urban agricultural lands, 2) quantification of soil gypsum, 3) enhanced pedon horizonation, 4) soil textural analysis, and 5) diagnostic subsurface horizon characterization; topics applicable to assessment of anthropogenic influence on soil which will be reviewed in this presentation. Beyond these applications, this presentation seeks to open dialog on even more soil science applications of PXRF such as salinity assessment and source sediment identification from subaqueous soil cores, with a goal of broadening the scope of scientific inquiry and building a compelling body of peer reviewed literature in support of its adoption by the USDA-NRCS as a sanctioned tool for field soil survey.