Regional geochemical baselines for Portuguese shelf sediments

• Published in: Environmental pollution (1987) Vol. 148; no. 2; pp. 418 - 427
• Main Authors: Mil-Homens, M., Stevens, R.L., Cato, I., Abrantes, F.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2007; Elsevier
• Subjects: aluminum; Aluminum - analysis; Applied sciences; Brackish; chromium; Chromium - analysis; Copper - analysis; data analysis; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Enrichment factors; environmental assessment; Environmental Monitoring - methods; Environmental Pollutants - analysis; Exact sciences and technology; Freshwater; geochemistry; Geologic Sediments - chemistry; Heavy metals; lead; Lead - analysis; Marine; Marine and continental quaternary; Marine sediments; metal concentration; Metals, Heavy - analysis; nickel; Nickel - analysis; Pollution; Pollution sources. Measurement results; Pollution, environment geology; Portugal; Portuguese continental shelf; Portuguese shelf; regional geochemical baseline; Regional geochemical baselines; sediment contamination; Soil and sediments pollution; spatial variation; Surficial geology; Time Factors; zinc; Zinc - analysis; Portugal; Portugal, Algarve; ANE, Portugal, Algarve; Portugal, Tejo R; Regional geochemical baselines; Portuguese shelf; Marine sediments; Enrichment factors; Heavy metals; Background concentration; continental shelf; trace elements; Enrichment factor; geochemistry; heavy metals; marine sediments; Coastal zone
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2006.12.007

Metal concentrations (Al, Cr, Cu, Ni, Pb and Zn) from the DGM-INETI archive data set have been examined for sediments collected during the 1970s from 267 sites on the Portuguese shelf. Due to the differences in the oceanographic and sedimentological settings between western and Algarve coasts, the archive data set is split in two segments. For both shelf segments, regional geochemical baselines (RGB) are defined using aluminium as a reference element. Seabed samples recovered in 2002 from four distinct areas of the Portuguese shelf are superimposed on these models to identify and compare possible metal enrichments relative to the natural distribution. Metal enrichments associated with anthropogenic influences are identified in three samples collected nearby the Tejo River and are characterised by the highest enrichment factors (EF; EF Pb < 3, EF Zn < 4). EF values close to 1 suggest a largely natural origin for metal distributions in sediments from the other areas included in the study. Background metal concentrations and their natural variability must be established before assessing anthropogenic impacts.