By means of 4 long boreholes, depths between 9 and 27 m, the sedimentary sequence of the Nalón River estuary has been studied in order to assess the impact of the anthropogenic mining activities developed in the Nalón watershed have had on the geochemical partition of heavy metals trapped in the sediments. The results have allowed the identification of two distinct parts in the sedimentary registry. The upper sediment layers in all the boreholes could have been attributed to the Anthropocene, because they presented a mineralogy and Pb isotopic signature correlated with the coal mining period. On the other hand, the deepest layers presented minerals and Pb isotopic signatures differentiable from the previous ones, attributing them to the natural Holocene. Within the alteration in the geochemical partition of sediments, records of the Anthropocene showed values of geochemical background for As, Hg, Pb and Zn much higher than those of the Holocene, attributing the enrichment of their concentrations in the cases of Pb and Zn to the contaminant contributions of coal mining, and in the cases of As and Hg to Hg mining.
