Cd transfers during marine sediment resuspension over short and long-term period: Associated risk for coastal water quality

Abstract

Cadmium (Cd) is a highly toxic metal, regularly monitored uniformly for water quality across Europe, but scarcely for sediments. This study was designed to compare the kinetics of Cd remobilization and the amplitude of its transfers with different marine sediments. The results showed a highly reproducible transfer kinetics. Dissolved Cd was strongly and quickly removed from the dissolved phase (from 5 min up to 7 h). Then, the dissolved Cd concentration increased progressively to reach a maximal value after two weeks of mixing. The influence of the resuspension intensity representing light wind-induced resuspension up to dredging operations was observed after 2 weeks. The intensity of the sediment resuspension clearly impacted the amplitude of Cd remobilization, dissolved Cd ranging from a few ngL^-1 to few hundreds of ngL^-1, exceeding the maximal dissolved Cd concentration accepted by the European Union Water Framework Directive (WFD-2008/105 32/EC).

Keywords: Cadmium; Environmental quality standards (EQS); Remobilization; Sediment resuspension; Water quality.