Partitioning of Fe and heavy metals in sediments from Odiel and Tinto Rivers (SW Spain)

Abstract

It has studied the fractionation of Fe and several metals in 24 suspended matter samples collected during two cruises in the Ria de Huelva surface water. In all cases are observed high concentrations of Fe (7,4%) and metals. Among metals the most elevated average concentrations correspond to Cu (2834 ppm) followed by Zn (1921 ppm), Pb (344 ppm), As (139 ppm), Cd (22 ppm) and Ni (19 ppm). These high concentrations match with the high amounts of these same elements in surface sediments of this estuarine system and are originated by the acid contributions of the Tinto and Odiel rivers. They are observed throughout the system, from the mixing zones of both rivers to the interchange channels with the near coast. The fractionation analysis indicates that an important part of the total concentration of the studied elements is associated to phases with high chemical mobility, thus, more of 50% of the As, Cd and Pb concentrations present in the suspended matter correspond to labiles or very labiles fractions.