Heavy metals in surface sediments near urban and industrial sewage discharges in the gulf of Trieste

Abstract

Chromium, copper and zinc, as possible pollution indicators and lithium as a lithogenic reference were determined in surface sediments, sampled in the Gulf of Trieste nearby the exits of sewage collectors, to check for clues of modifications occurring in these sediments during the last 20–30 years. A biplot obtained from the data matrix points out anomalously high concentrations of metals in the upper layers of the sediments, whereas the deepest layers are relatively unpolluted. The structures of our data set ‐ referred to polluted sites ‐ and of another set describing natural geochemical baselines of the metals for the Gulf of Trieste, were compared and studied using a univariate robust statistical test (Mann‐Whitney) and multivariate clustering methods. The results support the hypothesis of a noxious, recent anthropogenic pressure on the benthic environment caused by the collectors.