Sediments as monitors of heavy metal contamination in the Ave river basin (Portugal): multivariate analysis of data

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) were determined in river sediments collected at the Ave river basin (Portugal) to obtain a general classification scenery of the pollution in this highly polluted re gion. Multivariate data analysis techniques of clustering, principal compon ents and eigenvector projections were used in this classification. Five gen eral areas with different polluting characteristics were detected and sever al individual heavy metal concentration abnormalities were detected in rest ricted areas. A good correlation between the overall metal contamination de termined by multivariate analysis and metal pollution indexes for all sampl ing stations was obtained. Some preliminary experiments showed that the met al concentrations normalised to the volatile matter content in the sediment fraction with grain size < 63 mu m seems to be an adequate method for asse ssing metal pollution. (C) 1999 Elsevier Science Ltd. All rights reserved.