Original Article

Environmental Geology

, Volume 56, Issue 5, pp 833-843

First online:

Heavy metal contamination of coastal lagoon sediments by anthropogenic activities: the case of Nador (East Morocco)

  • M. K. BloundiAffiliated withEOST, Centre de Géochimie de la Surface, Université Louis Pasteur, CNRS Email author 
  • , J. DuplayAffiliated withEOST, Centre de Géochimie de la Surface, Université Louis Pasteur, CNRS
  • , G. QuarantaAffiliated withEOST, Centre de Géochimie de la Surface, Université Louis Pasteur, CNRS

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Abstract

Nador lagoon sediments (East Morocco) are contaminated by industrial iron mine tailings, urban dumps and untreated wastewaters from surrounding cities. The lagoon is an ecosystem of biological, scientific and socio-economic interests but its balance is threatened by pollution already marked by biodiversity changes and a modification of foraminifera and ostracods shell structures. The aim of the study is to assess the heavy metal contamination level and mobility by identifying the trapping phases. The study includes analyses by ICP-AES and ICP-MS, of, respectively, major (Si, Al, Mg, Ca, Fe, Mn, Ti, Na, K, P) and trace elements (Sr, Ba, V, Ni, Co, Cr, Zn, Cu, As, Pb, Cd) in sediments and suspended matter, heavy metals enrichment factors calculations and sequential extractions. Results show that sediments contain Zn, Cu, Pb, V, Cr, Co, As, Ni with minimum and maximum concentrations, respectively, of 4–1190 μg/g, 4–466 μg/g, 11–297 μg/g, 11–194 μg/g, 9–139 μg/g, 1–120 μg/g, 4–76 μg/g, 2–62 μg/g. High concentrations in Zn are also present in suspended matter. The enrichment factors show contamination in Zn, Pb and As firstly induced by the mining industry and secondly by unauthorized dumps and untreated wastewaters. Cr and Ni are bound to clays, whereas V, Co, Cu and Zn are related to oxides. Thus, the risk in metal mobility is for the latter elements and lies in the oxidation–reduction-changing conditions of sediments.

Keywords

Geochemistry Trace elements contamination Sediments Suspended matter Nador lagoon