Speciation of metals in contaminated sediments in the Kalmar County, Sweden : an initial approach toward sediment mining

Abstract: In response to the growing numbers of contaminated sites, concerns about proper management with reduced environmental footprints have been raised. In the present study, mining of highly contaminated sediments to recover valuable elements such as metals and nutrients is proposed as sustainable approach, both through enhancing resilience of ecosystems and remediation, beside probable turnovers. Thereby, in order to evaluate feasibility of metal recovery, fractionation of thirteen heavy and trace metals (Fe, Al, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn) in Oskarshamn harbor and Malmfjärden semi-enclosed bay surface sediments taken from five polluted locations in Kalmar County in southeast of Sweden was studied. The dissolution experiment by a modified BCR (Community Bureau of Reference, now SM&T) sequential extraction procedure (BCR-SEP) was used to determine the partitioning of elements. Oskarshamn and Malmfjärden sediments showed highest mobility for Zn and Cd, which can be leached out easily by small changes in environment conditions, whereas Al, Ba, and Hg in both sites, beside Cr and Fe in Malmfjärden exhibited high percentage in residual fraction. Moreover, total digestion results turn out that Oskarshamn in comparing to Malmfjärden sediments tended to result in larger contents of total extractable heavy metals (except Al), which is strongly attributed to factories, wastewater treatment plants, and ships traffic in Oskarshamn basin and diffusive sources in Malmfjärden. Despite the smaller magnitude of pollution in Malmfjärden relative to Oskarshamn, besides dredging and removal of sediments, in situ remediation techniques such as capping, using amendments and phytoremediation could be suggested. The results indicated that among different metals in the sediments, particularly in Oskarshamn, Cu and Pb followed by As, Cr and Ni can be considered for future sediment mining.