Using Geochemical Fingerprints for Assessing Sediment Source Apportionment in an Agricultural Catchment in Central Argentina

Abstract

In the hilly semi-arid region of central Argentina, where the agricultural frontier expands at the expense of natural ecosystems, soil erosion is one of the most alarming environmental problems. Thus, obtaining knowledge about the dynamics of erosive processes and identifying erosion hotspots constitutes a primary scientific objective. This investigation is focused on estimating the apportionments of main sources of sediments, at the mouth of a small catchment called Durazno del Medio, located in the province of San Luis, Argentina. Elemental Analysis, measured by Energy Dispersive X-ray Fluorescence (EDXRF), was used to select potential geochemical fingerprints of sediment. The unmixing model MixSIAR was applied to approximate the contribution of each identified source in the sediment accumulation areas at the mouth of the catchment. Potential sediment sources were selected using two criteria: (i) a hierarchical approach to identify the main geomorphological units (GUs) and (ii) the main land uses (LU), recognized by examining satellite images and field recognitions. The selected geochemical tracers were able to distinguish sources located in the Crystalline basement hills with loess-patched (CBH) as the main sediment contributors.

Tracking Sediment Provenance Applying a Linear Mixing Model Approach Using R’s FingerPro Package, in the Mining-Influenced Ocoña Watershed, Southern Peru

“…Assuming high mining activities in those areas, these results agree with the findings by Fang and Fan [76], who investigated sediment sources in the Shouchang watershed (southeastern China), concluding that most sediments were originated from human activities. Similarly, one of the main sediment sources found by Garcias et al [77] in Argentina was exotic forest plantations, normally characterized for yielding sediments after clearcutting and road construction, e.g., [78,79], while Tiecher et al [80] concluded that agricultural fields in Brazil are a significant source of sediments, even under no-tillage conditions, similar to the findings by Zhang et al [81] in Hampshire, UK. However, Liu et al [82] reported that agriculture represented less than 10% of sediment sources in the Lower Little Bow River (Alberta), with the majority of sources unknown.…”