Regional background values for metals in Sado sediments.

Abstract

This paper presents regional geochemical baselines for cadium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) determined using sediments of the Sado estuary. The baselines were calculated by analyzing 34 sediment samples selected from 3 sediment cores performed in the Sado basin alluvial plain at Arapouco, Laxique and Arez, located between 50 and 65 km upstream the estuary inlet and in the Comporta salt marshes, located in the central estuarine basin. The samples were selected based on their age and only samples older than ca. 3000 cal BP were analyzed to discard anthropic influence. Maximum values of Cd=4 Co=9, Cr=58, Cu=40, Ni=21, Pb=11, V=71 and Zn=56 mgKg-1 were achieved. These values can be applied as geochemical baselines for the Sado estuary in contamination studies or for the determination of the anthropic metal contribution in the area.