Distribution of trace metals in marine sediments of the Bay of Palma de Mallorca (Mallorca Island, Spain).

Metals were determined in surface bottom marine sediments of the Bay of Palma de Mallorca (Spain) by microwave-assisted acid-oxidant digestion and inductively coupled plasma-optical emission spectrometry in order to assess the level and distribution of potentially metallic pollutants. Average concentrations found were 1.2 ± 0.3 Al and 1.9 ± 0.9 Fe (in milligrams per gram), and 8 ± 2 Cr, 2 ± 1 Cu, 60 ± 10 Mn, 4 ± 1 Ni, 6 ± 4 Pb, 50 ± 7 Sn and 10 ± 3 Zn (in micrograms per gram). Enrichment factors using normalized values to Al were also calculated which indicated that sediments were Sn and Pb enriched. Sediments were fractionated by grain size: <63, 63-250, 250-500 and >500 (in micrometres), and the metals' affinity towards the different fractions was studied. The metals' affinity to the finer fraction was evidenced, excluding Sn and Mn that showed practically no affinity for fine grains. Latent variables were extracted from the data using principal components analysis. It allowed samples to be grouped in two clusters, and most of the metals (Al, Cr, Cu, Fe, Ni, Pb and Zn) showed a similar distribution pattern. Sn and Mn showed a distinct pattern.