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Impact of sample preparation methods for characterizing the geochemistry of soils and sediments by portable X‐ray fluorescence
Author(s) -
Goff Kathleen,
Schaetzl Randall J.,
Chakraborty Somsubhra,
Weindorf David C.,
Kasmerchak Chase,
Bettis E. Arthur
Publication year - 2020
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.1002/saj2.20004
Subject(s) - pellets , sample preparation , environmental science , mineralogy , fluorescence spectrometry , soil water , grinding , soil test , trace element , analytical chemistry (journal) , chemistry , environmental chemistry , soil science , materials science , fluorescence , metallurgy , chromatography , physics , quantum mechanics , composite material
We examined the impact of three different sample preparation methods on bulk soil geochemistry data obtained from a hand‐held, portable X‐ray fluorescence (pXRF) spectrometer. We generated data from a soil core recovered from the surface, downward into unaltered loess, and into a buried soil at a site in eastern Iowa. Samples were scanned (i) directly from field‐moist soil cores; (ii) after drying, grinding, and being loosely massed in plastic cups; and (iii) as pressed‐powder pellets. Data derived using these methods were compared with data obtained from a standard benchtop X‐ray fluorescence (XRF) unit. Generally, the results indicated that data from pressed powder pellets often provide the best correlation to benchtop XRF data, although the results were sometimes element or compound specific. Calcium oxide, Fe 2 O 3 , and K 2 O generally provided the strongest correlations between pXRF‐ and XRF‐reported values; SiO 2 data were more problematic. Field‐moist pXRF scans generally underestimated element concentrations, but the correlations between pXRF and benchtop XRF measurements were greatly improved after applying pXRF‐derived calibration standards. In summary, although element/compound data provided by pXRF showed significant relationships to benchtop XRF data, the results are improved with proper sample preparation (i.e., drying, grinding, pressing) and usually by calibrating the pXRF data against known standards.