Effect of salinity on heavy metal mobility and availability in intertidal sediments of the Scheldt estuary

G. Du Laing, R. De Vos, B. Vandecasteele, E. Lesage, F. M.G. Tack, M. G. Verloo

    Onderzoeksoutput: Bijdrage aan tijdschriftA1: Web of Science-artikel

    Uittreksel

    The effect of the flood water salinity on the mobility of heavy metals was studied for intertidal sediments of the Scheldt estuary (Belgium). Soils and sediments of 4 sampling sites were flooded with water of different salinities (0.5, 2.5, and 5 g NaCl L-1). Metal concentrations were monitored in pore water and surface water. To study the potential effects of flood water salinity on metal bioavailability, duckweed (Lemna minor) was grown in the surface water. The salinity was found to primarily enhance the mobility of Cd and its uptake by duckweed. Cadmium concentrations in pore water of soils and sediments and surrounding surface waters significantly exceeded sanitation thresholds and quality standards during flooding of initially oxidized sediments. Moreover, the effect was observed already at lower salinities of 0.5 g NaCl L-1. This implies that risks related to Cd uptake by organisms and Cd leaching to ground water are relevant when constructing flooding areas in the brackish zones of estuaries. These risks can be reduced by inducing sulphide precipitation because Cd is then immobilised as sulphide and its mobility becomes independent of flood water salinity. This could be achieved by permanently flooding the polluted sediments, because sulphates are sufficiently available in the river water of the brackish part of the estuary. © 2007 Elsevier Ltd. All rights reserved.
    TaalEngels
    TijdschriftEstuarine Coastal and Shelf Science
    Volume77
    Exemplaarnummer4
    Pagina's (van-tot)589-602
    Aantal pagina's14
    ISSN0272-7714
    DOI's
    StatusGepubliceerd - 10-mei-2008

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