Registro sedimentario en marmitas de erosion fluvial. Río Miño, Ourense

Abstract

The capacity of fluvial potholes to trap sediments led to the hypothesis that these deposits could serve as historical records. A sediment core, obtained from an erosion pothole, was studied. 11 samples (22 cm depth) were obtained. The 210Pb dating indicated that, in general, the pothole was gradually filled in the last 33-35 years. Using trace metals as indicators (Cu, Pb and V) it was possible to estimate their natural background (61±27mgCu·kg-1, 72±45 mgPb·kg-1 and 19±4 mgV·kg-1). After calculating the normalized enrichment factor (NEF), the core showed indexes indicative of possible-moderate contamination for Cu and Pb (average contents 141±45 mgCu·kg-1 and 141±46 mgPb·kg-1), particularly in a layer (1993-2009) that seems to be a mixture of sediments of different ages, coinciding in time with human interventions in the local environment. Sediments trapped in potholes (as traps) showed potential to be used as historical records