Lateral and vertical variations in contaminated sediments from the Tinto River area (Huelva, SW Spain): Incidence on tracemaker activity and implications of the palaeontological approach

Geochemical and ichnological analyses of the Tinto River area (SW Spain) reveal the presence of macro-tracemakers colonizing highly contaminated soils. We found high concentrations of heavy metals and related elements, mainly accumulated in the upper parts (biofilms and thin salty crusts). Some concentrations, including those of Cu, Zn and As, exceed the intervention levels for natural areas and indicate potentially toxic conditions. Ichnological analysis reveals the presence of biogenic structures produced by the activity of the earthworm Lumbricus terrestris and the coleoptera Platystethus. Both alternatives for colonization can be correlated with those used by fossil tracemakers, and they serve to better understand biotic recovery after bio-events in the past.