Calibration of Laser-Induced Breakdown Spectroscopy with Soils from the United States. (5252)
Authors:
M.H. Ebinger* - Los Alamos National Laboratory D.A. Cremers - Los Alamos National Laboratory M.L. Norfleet - USDA-NRCS, Auburn,AL
D.D. Breshears - Los Alamos National Laboratory C.W. Meyer - Los Alamos National Laboratory P.J. Unkefer - Los Alamos National Laboratory
Abstract:
Laser-induced breakdown spectroscopy (LIBS) was calibrated for carbon analysis using samples from several soil series throughout the United States. Overall, correlation between conventional analyses (dry combustion) and LIBS was good. LIBS proved more sensitive to carbon from coarse and loamy
textured soils than from clayey soils, possibly due to the amount of material vaporized in the plasma.
Thus, calibrations for coarse to medium textured soils were less variable than from finer soils. These results indicate that LIBS analysis for carbon will require calibration with soils of interest for various investigations, not a universal calibration within each study. While correlation coefficients were generally large (0.8 to 0.95), variation in the LIBS signal was observed with each soil series analyzed.
This variation was due to heterogeneities in the various soils at the sub 1-mm scale, such as carbon deposited as discrete humic particles, coatings on mineral surfaces, and shielding of carbon from the impinging laser by larger soil particles. Variation in LIBS signal was smoothed considerably by increasing the number of collections (shots) per sample and the time allowed for signal accumulation.
Our work shows that LIBS can be a highly effective and rapid analytical tool for carbon analysis of soils if sample micro-heterogeneity is factored into the analyses.
Speaker Information: Michael Ebinger, Los Alamos National Laboratory, EES-2 MS J495, Los Alamos National Laboratory, Los Alamos, NM 87545; Phone: 505-667-3331; E-mail: [email protected]
Session Information: Tuesday, November 2, 2004, 3:00 PM-5:00 PM Presentation Start: 3:00 PM (Poster Board Number: 1836)
Keywords: Soil Carbon Analysis; LIBS; Calibration method; U. S. Soils
