A comparison of an optimised sequential extraction procedure and dilute acid leaching of elements in anoxic sediments, including the effects of oxidation on sediment metal partitioning.

The effect of oxidation of anoxic sediment upon the extraction of 13 elements (Cd, Sn, Sb, Pb, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As) using the optimised Community Bureau of Reference of the European Commission (BCR) sequential extraction procedure and a dilute acid partial extraction procedure (4h, 1 molL(-1) HCl) was investigated. Elements commonly associated with the sulfidic phase, Cd, Cu, Pb, Zn and Fe exhibited the most significant changes under the BCR sequential extraction procedure. Cd, Cu, Zn, and to a lesser extent Pb, were redistributed into the weak acid extractable fraction upon oxidation of the anoxic sediment and Fe was redistributed into the reducible fraction as expected, but an increase was also observed in the residual Fe.

A study of metal and metalloid contaminant availability in Antarctic marine sediments.

Previous studies of impacted sites near Casey Station, Antarctica, have revealed elevated concentrations of metals and metalloids, particularly Cd, Cu, Fe, Pb, Sn and Zn in marine sediments. However, attempts to understand the availability and mobility of contaminant elements have not provided a true understanding of speciation. The current work shows, for the first time, that sediments in Brown Bay, an embayment adjacent to the Thala Valley waste disposal site, have elevated concentrations of sulfide, well in excess of that required to bind contaminant metals such as Cd, Cu, Pb and Zn.

Monitoring the remediation of a near shore waste disposal site in Antarctica using the amphipod Paramoera walkeri and diffusive gradients in thin films (DGTs).

The water quality of a marine embayment (Brown Bay) was monitored during the remediation of an abandoned waste disposal site at Casey Station, East Antarctica, using a combination of biomonitoring and chemical methods. The Antarctic amphipod Paramoera walkeri, in field mesocosms suspended in the water column, was deployed adjacent to the site and at two reference sites for periods of 14 days, repeated three times during the remediation period (December to February). Diffusive gradients in thin film (DGT) samplers were deployed for the same periods to provide estimates of dissolved metals.

Evaluation of diffusive gradients in thin film (DGT) samplers for measuring contaminants in the Antarctic marine environment.

This work has been the first application of DGT samplers for measuring metals in water and sediment porewater in the Antarctic environment, and whilst DGT water sampling was restricted to quantification of Cd, Fe and Ni, preconcentration using Empore chelating disks provided results for an additional nine elements (Sn, Pb, Al, Cr, Mn, Co, Cu, Zn, As). Although higher concentrations were measured for some metals (Cd, Ni, Pb) using the Empore technique, most likely due to particulate-bound or colloidal species becoming entrapped in the Empore chelating disks, heavy metal concentrations in the impacted Brown Bay were found to be comparable with the non-impacted O'Brien Bay. Sediment porewater sampling using DGT also indicated little difference between Brown Bay and O'Brien Bay for many metals (Cd, Al, Cr, Co, Ni, Cu), however, greater amounts of Pb, Mn, Fe and As were accumulated in DGT probes deployed in Brown Bay compared with O'Brien Bay, and a higher accumulation of Sn was observed in Brown Bay inner than any of the other three sites sampled.