Use of neutralized industrial residue to stabilize trace elements (Cu, Cd, Zn, As, Mo, and Cr) in marine dredged sediment from South-East of France Mehwish Taneez a, * , Nicolas Marmier a , Charlotte Hurel b a Universit e Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, 06108, France b Universit e Nice Sophia Antipolis, CNRS, LPMC, UMR 7336, Parc Valrose, 06108 Nice, France highlights  Bauxite residue (bauxaline ® ) was neutralized with gypsum to lower its pH.  Neutralized bauxaline ® was used as amendment at 5% and 20% for trace elements stabilization in marine dredge sediment.  20% neutralized bauxaline ® immobilized significantly cationic pollutants.  Leachates toxicity towards rotifers (Brachionus plicatilis) was sufficiently decreased with 20% amendment application. article info Article history: Received 29 September 2015 Received in revised form 13 January 2016 Accepted 2 February 2016 Available online xxx Handling Editor: Martine Leermakers Keywords: Neutralized bauxaline ® Gypsum addition Trace elements Marine dredged sediment Stabilization Ecotoxicity abstract Management of marine dredged sediments polluted with trace elements is prime issue in the French Mediterranean coast. The polluted sediments possess ecological threats to surrounding environment on land disposal. Therefore, stabilization of contaminants in multi-contaminated marine dredged sediment is a promising technique. Present study aimed to assess the effect of gypsum neutralized bauxaline ® (bauxite residue) to decrease the availability of pollutants and inherent toxicity of marine dredged sediment. Bauxaline ® , (alumia industry waste) contains high content of iron oxide but its high alkalinity makes it not suitable for the stabilization of all trace elements from multi-contaminated dredged sedi- ments. In this study, neutralized bauxaline ® was prepared by mixing bauxaline ® with 5% of plaster. Experiments were carried out for 3 months to study the effect of 5% and 20% amendment rate on the availability of Cu, Cd, Zn, As, Mo, and Cr. Trace elements concentration, pH, EC and dissolved organic carbon were measured in all leachates. Toxicity of leachates was assessed against marine rotifers Bra- chionus plicatilis. The Results showed that both treatments have immobilization capacity against different pollutants. Significant stabilization of contaminants (Cu, Cd, Zn) was achieved with 20% application rate whereas As, Mo, and Cr were slightly stabilized. Toxicity results revealed that leachates collected from treated sediment were less toxic than the control sediment. These results suggest that application of neutralized bauxaline ® to dredged sediment is an effective approach to manage large quantities of dredged sediments as well as bauxite residue itself. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The presence of contaminants in aquatic environment has attracted global attention in the recent years due to their toxicity, abundance and persistence (Sin et al., 2001). Trace elements can be easily adsorbed onto particles, deposited and accumulated in the sediments, making sediments a sink and an ultimate source of contaminants. Contaminants can be released back into water col- umn during natural (tidal movements or storms) and anthropo- genic processes (dredging, dredged disposal and fishing) that provoke little variations of pH or redox potential of interstitial water (Calmano et al., 1996; Zoumis et al., 2001; Eggleton and Thomas, 2004). Mediterranean Sea is vulnerable to chemical contamination due to its semi-closed environment with low freshwater inputs. During the past decades, industrial, agricultural and urban waste have been discharged into the Mediterranean Sea * Corresponding author. E-mail address: mehtaneez@gmail.com (M. Taneez). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere http://dx.doi.org/10.1016/j.chemosphere.2016.02.014 0045-6535/© 2016 Elsevier Ltd. All rights reserved. Chemosphere 150 (2016) 116e122