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Direct Soil Gypsum Quantification via Portable X‐Ray Fluorescence Spectrometry
Author(s) -
Weindorf David C.,
Herrero Juan,
Castañeda Carmen,
Bakr Noura,
Swanhart Samantha
Publication year - 2013
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 - 10.2136/sssaj2013.05.0170
Subject(s) - gypsum , soil water , linear regression , soil test , environmental science , soil science , mineralogy , chemistry , mathematics , materials science , statistics , metallurgy
Soil scientists have long struggled with an effective method for quantifying gypsum content in soils. Several methods exist, but each is fraught with problems. Recent enhancements to portable X‐ray fluorescence (PXRF) spectrometers have provided better detection limits especially for lighter elements such as S, a key component of gypsum. Thus, this research aimed to test the effectiveness of PXRF as a means of directly quantifying gypsum in soils. A total of 102 soil samples containing a wide variety of gypsum (∼2–95%) were subjected to both traditional laboratory analysis (thermogravimetry) and elemental analysis via PXRF. Simple linear regression and multiple linear regression were used to establish the relationship between the two datasets. Log transformation of some datasets was necessary to normalize the data. Using simple linear regression for Ca, laboratory data and PXRF Ca data produced an R 2 of 0.8794. Similarly, simple linear regression for laboratory‐quantified gypsum vs. PXRF S produced an R 2 of 0.9120. Multiple linear regression of laboratory quantified gypsum vs. both PXRF S and Ca produced an R 2 of 0.9127. No significant differences were observed between model generation and validation datasets. Overall, PXRF shows great promise for the direct quantification of gypsum in soils.