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The concentration profiles of Co, Ni, Cu, Zn, Sc, Y, As, Cd, Pb, U and the rare earth elements (REE) were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in three sediment cores sampled in the western branch of Lake Como (northern Italy). This hydrographically closed branch has a complex morphology, with a maximum depth of 425 m and an approximate length of 30 km and it is affected to different extents by direct discharges and atmospheric depositions. The present study is the first attempt to deeply investigate trace element profiles in the sediments of this lake. The concentration trends of cores sampled in different zones were compared and the different patterns were interpreted on the basis of local runoff and/or global atmospheric sources. The concentrations of Cr, Zn, Pb, Cd and Cu, which are representative proxies of anthropogenic activities, were found to increase moving toward the tip of the branch, where human activities are concentrated. A distinction between atmospheric, runoff and crustal contribution to element levels in the sediment cores was proposed based on both profile analysis and principal component analysis (PCA). [ABSTRACT FROM AUTHOR]

A chemometric approach based on Principal Component Analysis (PCA) has been proposed, in order to study chemical features (major and minor ions, total alkalinity, dissolved silica) of surface and deep waters of Lake Como (Northern Italy). The method allowed us to investigate the correlations between the analyzed ions in an easy-to-see way, using bi-dimensional graphs. In wintertime, the ionic composition of Lake Como waters seems to be mainly related to the geological composition of the lake basin, with a crystalline bedrock on the northern side and a sedimentary cover in the southern part. The presence of contaminants such as bromide and nitrite in water columns is also evidenced and discussed. [ABSTRACT FROM AUTHOR]