Combining EDXRF and DRIFT-MIRS to distinguish sedimentary sources in an agricultural catchment of Argentina : Identification of suitable fingerprint elements

Abstract

Sediment transport and the associated deposition process are key environmental problems in the semi-arid center of Argentina where the agricultural frontier and new land uses grow at the expense of native vegetation. Using sediment source fingerprinting techniques could be a way of identifying hot spots critiques of land degradation. In this research we explore the use of natural elements in soil to identify sedimentary sources in a small basin in the province of San Luis, Argentina. Soil samples were collected in different points of the basin, representing different land use (source samples) and sediments samples were taken along the stream (mixed samples). Concentrations of possible fingerprint elements were measured using EDXRF technique. Additionally, multivariate PLS analysis was applied to the infrared spectral data of the samples. With the aim of validate the procedure, two artificial mixtures were made up with known proportions of source samples. Fingerprints elements were identified obtaining with them a very good reconstruction of the source proportions in the artificial mixtures. DRIFT-MIRS PLS analysis shows a good correlation between MIRS spectra and the identified fingerprint elements.