Temporal clustering of metals in a short sediment core of the Cascais Canyon (Portuguese Margin)

Authors

  • Mário Mil-Homens Laboratório Nacional de Energia e Geologia, I.P., Unidade de Geologia Marinha
  • Ana M. Costa Laboratório Nacional de Energia e Geologia, I.P., Unidade de Geologia Marinha
  • Susana M. Lebreiro Geological Survey of Spain, Dept. of Geosciences Research and Prediction
  • João Canário Instituto National de Recursos Biológicos, Instituto de Investigação das Pescas e do Mar (IPIMAR)
  • Cristina Lopes Laboratório Nacional de Energia e Geologia, I.P., Unidade de Geologia Marinha
  • Filomena Mouro Laboratório Nacional de Energia e Geologia, I.P., Laboratório de Análises Químicas
  • Manuela Mateus Laboratório Nacional de Energia e Geologia, I.P., Laboratório de Análises Químicas
  • Henko de Stigter Royal Netherlands Institute for Sea Research, Department of Marine Chemistry and Geology
  • Thomas Richter Royal Netherlands Institute for Sea Research, Department of Marine Chemistry and Geology
  • Vasco Branco Instituto National de Recursos Biológicos, Instituto de Investigação das Pescas e do Mar (IPIMAR)
  • M. Ascensão Trancoso Laboratório Nacional de Energia e Geologia, I.P., Laboratório de Análises Químicas
  • Zenaida Melo Laboratório Nacional de Energia e Geologia, I.P., Laboratório de Análises Químicas
  • Wim Boer Royal Netherlands Institute for Sea Research, Department of Marine Chemistry and Geology

DOI:

https://doi.org/10.3989/scimar.2010.74s1089

Keywords:

Portuguese Margin, Cascais Canyon, sediment, heavy metals, cluster analysis, enrichment factors

Abstract


The Cascais Canyon delivers contaminated sediments from the shelf to the deep marine environment. Multi-core PE252-32, located at 2100 m water depth in the canyon, records the latest 300 years of sedimentation. It was dated by 210Pb and analyzed texturally and geochemically for major elements and selected trace metals (Cu, Cr, Hg, Li, Ni, Pb and Zn). Cluster analysis performed on the down-core geochemical data identified four groups of variables related by grain-size, geochemical source and composition. Mercury, Pb and Zn were grouped in a cluster representing the anthropogenic component. Cluster analysis was applied again particularly to the latter cluster relatively to depth, in order to constrain the onset and temporal evolution of anthropogenic contamination. A second clustering, made on the basis of Hg, Pb and Zn, grouped samples by age and degree of anthropogenic contamination. One cluster contained relatively uncontaminated samples older than 1900 AD, and another cluster samples younger than 1900 AD with distinct metal enrichment. Maximum enrichments occurred during the early 1980s, followed by a slight recovery from the mid-1980s to the present. Mercury was the element with the highest enrichment factor (EFHg=5). Despite relatively low accumulation rates at this core location, our results show the importance of the Cascais Canyon as a transport route for contaminated sediments from the Tagus prodelta into the deep regions of the Portuguese Margin.

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Published

2010-12-30

How to Cite

1.
Mil-Homens M, Costa AM, Lebreiro SM, Canário J, Lopes C, Mouro F, Mateus M, de Stigter H, Richter T, Branco V, Ascensão Trancoso M, Melo Z, Boer W. Temporal clustering of metals in a short sediment core of the Cascais Canyon (Portuguese Margin). Sci. mar. [Internet]. 2010Dec.30 [cited 2024Mar.29];74(S1):89-98. Available from: https://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/1221

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