『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 4-1190μg/g, 4-466μg/g, 11-297μg/g, 11-194μg/g, 9-139μg/g, 1-120μg/g, 4-76μg/g, 2-62μg/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』

Introduction
Study area
Materials and methods
　Sampling
　Mineralogy
　Geochemistry and enrichment factors
　Sequential extraction
　Suspended matter analysis
Results
　Mineralogy
　Heavy metal concentrations in lagoon sediments
　Correlation between major and trace elements
　Contamination level
　Heavy metals trapping phases
　Heavy metals in suspended matter
Conclusion
Acknowledgments
References