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Total Petroleum Hydrocarbon Concentration Prediction in Soils Using Diffuse Reflectance Infrared Spectroscopy
Author(s) -
Forrester Sean T.,
Janik Les J.,
McLaughlin Michael J.,
Soriano-Disla José M.,
Stewart Richard,
Dearman Ben
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/sssaj2012.0201
Subject(s) - partial least squares regression , total petroleum hydrocarbon , diffuse reflectance infrared fourier transform , soil water , coefficient of determination , analytical chemistry (journal) , chemistry , hydrocarbon , diffuse reflection , correlation coefficient , infrared , infrared spectroscopy , calibration , near infrared spectroscopy , soil test , environmental chemistry , soil science , environmental science , soil contamination , mathematics , statistics , optics , biochemistry , physics , organic chemistry , photocatalysis , catalysis
Partial least squares (PLS) calibration models, from diffuse reflectance infrared Fourier‐transform (DRIFT) spectra, were developed for the prediction of total petroleum hydrocarbon (TPH) concentrations in contaminated soils. Soils were collected from sites in southeastern Australia known to be contaminated with TPH. Regression models were derived for concentration ranges of 0 to 32,600, 0 to 5000, 0 to 15,000, and 15,000 to 32,600 mg kg −1 . For each range, PLS models using selected near‐infrared (NIR) and mid‐infrared (MIR) frequencies were tested. The aliphatic alkyl stretching vibration regions were the most sensitive to TPH: NIR frequencies at 4500 to 4100 cm −1 and MIR at 3000 to 4600 cm −1 . The MIR range included two –CH 3 peaks, one at 2950 cm −1 and the other near 2730 cm −1 , having strong correlation with TPH at low and high TPH concentrations, respectively. These peaks were considered to be either weak or absent in natural soil organic matter relative to the usual –CH 2 region at 2930 to 2850 cm −1 . The PLS regression analysis using the combined 2980 to 2950 and 2777 to 2650 cm −1 MIR frequency regions for the 0 to 15,000 mg kg −1 set resulted in a ratio of prediction deviation of 3.7 (“analytical quality”), coefficient of determination ( R 2 ) = 0.93, and root mean square error of cross‐validation of 564 mg kg −1 . Using these MIR frequencies, the DRIFT infrared technique showed the potential to be a rapid and accurate nondestructive method to determine TPH concentrations in contaminated soils, potentially adaptable to in‐field use.