On the heavy elements content of sediments and rocks from two semiclosed ecosystems: Proglacial Lake Balea (Fagara Mountains) and Crater Lake St. Ana (Harghita Mountains)

The content of seven heavy elements (natural Sc and Cr, Co, As, Sb, Br and Se as possible pollutants) was determined by the Neutron Activation Analysis (NAA) in 29 samples of sediments and surrounding rocks collected from proglacial Lake Balea (Fagara Mountains) and crater St. Ana Lake (Harghita Mountains) to estimate the degree of anthropogenic pollution, as well as the sediments provenance. Consequently, we have found that, within experimental uncertainties, the content of the considered elements in sediments was close to those of surrounding rocks, and, at the same time, comparable with the normal environmental content as defined by the Romanian Regulations, which enabled us to consider them as normal, nonpolluting constituents of lake sediments. A further R-mode, Principal Component Analysis (PCA), performed for each lake, showed that Sc, Cr, and Co, on the one hand, and As, Sb, Br and Sb, on the other, form two distinct clusters, regardless of the lake, while the Q-mode analysis pointed to a different lake geochemistry with respect to sediments as well as rocks origin.