172-1 Using NIR Spectroscopy to Predict Sorption of Contaminants at Field Scale.
Poster Number 1410
See more from this Division: SSSA Division: Soil PhysicsSee more from this Session: Soil Hydrology - Patterns and Process Interactions in Space and Time: II
Forty five bulk soil samples were collected from an agricultural field in Estrup,Denmark, in a 15 m x 15 m grid. Samples were air dried and 2-mm sieved. Samples were analyzed for texture, iron and aluminium oxides, pH, and organic carbon content. Sorption coefficients were obtained from a batch equilibration experiment. Soil samples were scanned with a bench top NIR instrument covering the full visible and near infrared range between 350-2500 nm. Partial Least Squares (PLS) regression with full cross-validation was used to correlate the soil spectra with Kd values and soil properties. he sorption coefficients ranged from 345 to 886 L kg-1 and from 162 to 536 L kg-1 for phenanthrene and glyphosate, respectively. By means of the NIR spectra we were able to predict phenanthre (r2 = 0.938, RMSECV = 36.93) and glyphosate sorption (r2 = 0.616, RMSECV = 61.89). The normalized regression coefficients showed that phenanthrene sorption is correlated with total organic carbon and aluminium oxides, and glyphosate sorption with clay content and iron oxides. Predicted Kd values caught the spatial variability within the field suggesting that NIR - Kd predictions can be used as input for leaching risk assessment models.
See more from this Session: Soil Hydrology - Patterns and Process Interactions in Space and Time: II