Chemometric tools to evaluate the spatial distribution of trace metals in surface sediments of two Spanish rias

A suite of relevant trace metals (Hg, Pb, Cd, Cu, Zn and Ni) was measured in surface sediment samples to assess the environmental situation of the largest two Atlantic Spanish 'rias' (a form of estuaries, ria of Pontevedra, ROP, and ria of Vigo, ROV).The level of contamination originated by these metals was assessed against international guidelines, the threshold effect. ERL, and the midrange effect, ERM. Six unsupervised and supervised multivariate chemometric techniques were applied to model each ria, compare them and select those metals that characterize the samples. This is first time that such a study is performed for these two important seafood-producing areas. Maximum concentrations at ROP occurred in the vicinities of an inner island, where Cu, Zn, Ni and Pb presented concentrations over the ERL and Hg over the ERM. Highest concentrations of metals in ROV were observed in the proximities of Vigo shipyards and port, except for Pb, with peak values in San Simon Bay. ERL limits were exceeded in the inner part of this ria for Cu, Zn and Hg and in a wider area for Pb and Ni. Levels for Pb went beyond the ERM boundary in the axial part of San Simon Bay. In general, the distribution of the metals was more homogeneous in ria of Pontevedra than in ria of Vigo (where three morphological zones were characterized). Both rias could be differentiated using only two metals: Ni and Hg, as deduced from the multivariate techniques. 0 2011 Elsevier B.V. All rights reserved.