Trace metal distribution in Ria de Aveiro (northwestern Portuguese coast) sediments

Citation

Pastorinho MR, Telfer T & Soares AMVM (2004) Trace metal distribution in Ria de Aveiro (northwestern Portuguese coast) sediments. Fourth SETAC World Congress: 25th Annual Meeting in North America, Portland, OR, USA, 14.11.2004-18.11.2004.

Abstract
A great variety of substances (both natural and synthetic) is poured and spilled into estuarine systems, among which are metals. Once released into the aquatic environment metals may interact with suspended matter, and subsequently be removed from the water column by deposition into sediments. Thus, sediments act as storage compartments and repository for toxic chemicals, hence can be indicators of past pollution events. The present study evaluated the distribution of trace metals in surface sediments in 50 sampling sites in the Ria de Aveiro, a shallow coastal lagoon in the Northwest Atlantic coast of Portugal. Six metals (all EPA priority pollutant) aluminum, cadmium, chromium, copper, lead and zinc were identified and measured by Graphite Furnace Atomic Absorption Spectroscopy (GF-AAS). Percentage of organic carbon and C/N ratios were calculated and environmental parameters (dissolved oxygen, pH, conductivity and temperature) were measured. In general, good correlations were established between the analyzed metals and aluminum associated with continental input and river runoff (Cr>Pb>Cu>Zn with the exception of Cd). A limited correlation was established between metals and organic carbon (with the exception of Cd). Maximum C/N values were not necessarily observed at stations with the highest Organic carbon percentage. The main effluent of this lagoon (Rio Vouga) showed different trends regarding organic carbon with very low correlations to metals (exception to Zn). Aluminum correlations were good with all metals but lead and chromium, that showed the highest absolute levels.

Keywords
sediment; heavy metals; organic carbon; coastal lagoon