A study of heavy metal pollution in the Tinto-Odiel estuary in southwestern Spain using factor analysis

The estuary of Odiel and Tinto rivers, located on the southwestern coast of the Iberian Peninsula, receives acidic fluvial water discharges with high concentrations of sulphates and heavy metals from these rivers. In addition, a big industrial complex which efflues directly on the system is located in the same estuary. The effluents induce the presence in the estuary of high concentrations of heavy metals and phospates (nutrients). The application of factorial analysis techniques on the nutrients and heavy metal concentrations in 46 water samples taken from 32 different sampling stations located along the estuary, allows three groups of elements and compounds with a distinct origin to be determinated. So, Cu and Zn have a clear fluvial provenance, whereas PO₄ and As are clearly industrial wastes and Cl, K, Ca, Li, Rb and Sr come from the sea. From the factorial analyses we can deduce the existence of two agents controlling the behavior of the analyzed elements, which are: the tidal exchange with the open sea and the fluvial supply. Received: 20 November 1998 · Accepted: 11 August 1999