Statistical comparison of trace metal concentrations in wild mussels (Mytilus galloprovincialis) in selected sites of Galicia and Gulf of Biscay (Spain)

Concentrations of five trace metals (Cd, Hg, Pb, Cu and Zn) in wild mussels (Mytilus galloprovincialis) from the Galician and Gulf of Biscay areas in Spain were monitored from 2000 to 2004. A pool of mussel soft tissue was prepared using 50 or more individuals representing the available size range (35–60 mm) present at the sampling points (A Coruña, Pontevedra and Vigo–Galicia, NW of Spain—and Avilés, Bilbao and Santander–Gulf of Biscay). Metals were analysed by atomic absorption spectrometry, AAS, (flame–AAS: Cu and Zn; graphite furnace–AAS: Cd and Pb; flow injection-cold vapour–AAS: total Hg). Quality of the chemical analyses was assessed by participation in periodic QUASIMEME intercalibration exercises carried out from 2000 to 2004, while the present study was developed . Univariate statistical studies, Anova (Analysis of the Variance) and Principal Component Analysis (autoscaled data, Varimax rotation) were carried out. Differences between the two areas as well as certain temporal trends were found and, in general, the Gulf of Biscay samples showed higher metallic contents, mainly close to Avilés, where iron and steel factories thrown residues for years into a nearby coastal area.