TY - JOUR
T1 - Field-scale predictions of soil contaminant sorption using visible-near infrared spectroscopy
AU - Paradelo Pérez, Marcos
AU - Hermansen, Cecilie
AU - Knadel, Maria
AU - Møldrup, Per
AU - Greve, Mogens Humlekrog
AU - de Jonge, Lis Wollesen
PY - 2016
Y1 - 2016
N2 - Models used to evaluate leaching of contaminants to groundwater are very sensitive to sorption coefficients (Kd). These models need reliable Kd data at the field scale, but the number of samples required makes the classic batch sorption experiments inappropriate for this purpose. Since visible-near infrared (vis-NIR) spectroscopy is an inexpensive and fast method, it has been used for predicting soil properties related to soil sorption capacity. In this study, we aimed to predict the spatial variation of Kd from vis-NIR spectra for two contaminants: phenanthrene (sorbed on organic fractions) and glyphosate (sorbed on mineral fractions). Forty-five bulk soil samples were collected from an agricultural field in Estrup, Denmark, in a 15 m × 15 m grid. Samples were air-dried, sieved to 2 mm and analysed for selected soil properties. Sorption coefficients were obtained from a batch equilibration experiment. Soil samples were measured with a bench-top spectrometer covering the vis-NIR range between 400 nm and 2500 nm. Partial least squares regression with full cross-validation was used to correlate the soil spectra with Kd values and soil properties. The sorption coefficients ranged from 345 L kg-1 to 886 L kg-1 and from 162 L kg-1 to 536 L kg-1 for phenanthrene and glyphosate, respectively. The regression coefficients showed that phenanthrenesorption was correlated with total organic carbon, aluminium oxides and cation exchange capacity, and glyphosate sorption with clay minerals and iron oxides. By means of the vis-NIR spectra we were able to predict phenanthrene (R2 = 0.95, RMSECV = 31 L kg-1) and glyphosate (R2 = 0.79, RMSECV = 45 L kg-1) sorption capacities. A model using vis-NIR spectra plus pH values improved the prediction of glyphosate sorption capacity (R2 = 0.88, RMSECV = 34 L kg-1). The models obtained from vis-NIR spectra successfullypredicted Kd within the investigated field, indicating the potential of vis-NIR spectroscopy as a fast method for determining Kd for input to leaching risk assessment models. However, further studies of different soil types and geographical scales are needed to confirm our findings. © 2015 IM Publications LLP. All rights reserved.
AB - Models used to evaluate leaching of contaminants to groundwater are very sensitive to sorption coefficients (Kd). These models need reliable Kd data at the field scale, but the number of samples required makes the classic batch sorption experiments inappropriate for this purpose. Since visible-near infrared (vis-NIR) spectroscopy is an inexpensive and fast method, it has been used for predicting soil properties related to soil sorption capacity. In this study, we aimed to predict the spatial variation of Kd from vis-NIR spectra for two contaminants: phenanthrene (sorbed on organic fractions) and glyphosate (sorbed on mineral fractions). Forty-five bulk soil samples were collected from an agricultural field in Estrup, Denmark, in a 15 m × 15 m grid. Samples were air-dried, sieved to 2 mm and analysed for selected soil properties. Sorption coefficients were obtained from a batch equilibration experiment. Soil samples were measured with a bench-top spectrometer covering the vis-NIR range between 400 nm and 2500 nm. Partial least squares regression with full cross-validation was used to correlate the soil spectra with Kd values and soil properties. The sorption coefficients ranged from 345 L kg-1 to 886 L kg-1 and from 162 L kg-1 to 536 L kg-1 for phenanthrene and glyphosate, respectively. The regression coefficients showed that phenanthrenesorption was correlated with total organic carbon, aluminium oxides and cation exchange capacity, and glyphosate sorption with clay minerals and iron oxides. By means of the vis-NIR spectra we were able to predict phenanthrene (R2 = 0.95, RMSECV = 31 L kg-1) and glyphosate (R2 = 0.79, RMSECV = 45 L kg-1) sorption capacities. A model using vis-NIR spectra plus pH values improved the prediction of glyphosate sorption capacity (R2 = 0.88, RMSECV = 34 L kg-1). The models obtained from vis-NIR spectra successfullypredicted Kd within the investigated field, indicating the potential of vis-NIR spectroscopy as a fast method for determining Kd for input to leaching risk assessment models. However, further studies of different soil types and geographical scales are needed to confirm our findings. © 2015 IM Publications LLP. All rights reserved.
KW - Field scale
KW - Glyphosate
KW - Multivariate analysis
KW - Phenanthrene
KW - Soil sorption coefficients
KW - Visible-near infrared reflectance spectroscop
KW - Field scale
KW - Glyphosate
KW - Multivariate analysis
KW - Phenanthrene
KW - Soil sorption coefficients
KW - Visible-near infrared reflectance spectroscop
U2 - 10.1255/jnirs.1228
DO - 10.1255/jnirs.1228
M3 - Journal article
SN - 0967-0335
VL - 24
SP - 281
EP - 291
JO - Journal of Near Infrared Spectroscopy
JF - Journal of Near Infrared Spectroscopy
IS - 3
ER -