The geochemical composition of the surface sediments has been analyzed for three estuaries located in the
Huelva coast: Guadiana, Piedras and Ría de Huelva (Tinto and Odiel river estuaries) and it has determined
the Enrichment Factor for analyzed elements. Between studied major elements, detach the high
concentrations of Fe2O3 and P2O5 present in the Ría de Huelva sediments, with EF values of 4 and 15,
respectively. In both cases the origin of these concentrations is antropogenic. Fe2O3 is introduced to the
estuary by the acid contributions of the Tinto and Odiel rivers, and the P2O5 result from the spills of the
phosphatic rocks. The sediments of the Guadiana and Piedras rivers show no significant EF in studied
metals. On the contrary, the Ría de Huelva sediments show EF very high for metals related to the acid mine
drainage of mine, thus the Cu displays EF values of 75.6, 36.9 for Zn and 58 for Pb. The three cases exceed
the average concentrations of 750 ppm. This indicates that the Ría de Huelva sediments present a bad
environmental quality. The Guadiana and Piedras estuaries are not observed significant antropic metal
contributions and can be considered that they maintain a good environmental quality