Sequential extraction analysis provides decision-making tools for the use of contaminated sediments

Abstract

To construct a new tourist harbour in Marina di Ragusa (Sicily), the dredging of 300,000 m³ of marine sediment is required. To evaluate potential disposal options, a detailed physico-chemical characterisation of this material is needed. A very cost-effective solution is represented by the re-use of the dredged material for beach nourishment. To this aim, compliance with environmental standards and a strong homogeneity between the receiving beach and the source sediments must be proved. Analytical determinations for the main parameters show an arsenic content exceeding the Italian quality standard (12 mg·kg⁻¹). In order to evaluate arsenic mobility and availability, and therefore the actual release into the environment, a three-step sequential extraction procedure was applied to a limited number of samples. The results obtained seem to exclude the risk, showing that arsenic is almost totally bound to the resistant fraction and thus does not represent an impediment to the beneficial re-use of sediment.

Keywords:

• arsenic
• sediments
• sequential extraction
• metals’ mobility
• nourishment