Four replicate sediment samples were collected on SCUBA from 3 sites near Scott Base (SB1, SB2, SB3), 2 sites near McMurdo Station (MM-0, MM-1), 1 site at Cape Armitage (CA), 1 site at Cape Evans (CE) and 1 site near Turtle Rock. The top 5 cm of sediment was collected from depths between 18 and 25 m, within a 20 metre radius of each site and stored frozen. Samples were later freeze dried, coarse sieved and the <2 mm fraction ground.
CLAM AND SPONGE SAMPLING
Five mature soft-shelled clams Laternula elliptica, were collected by hand and stored frozen. Four replicate biopsy samples of the sponges Homaxinella balfourensis, Mycale acerata and Sphaerotylus antarcticus were collected, blotted dry and stored frozen. The soft tissue from the clams and the sponge tissue were later freeze dried and ground.
METAL ANALYSIS IN SEDIMENTS, CLAMS AND SPONGES
After digestion, the sediment, clams and sponge samples were analysed for total Cu, Zn, Cd and Pb concentrations using inductively coupled plasma-atomic emission spectrometry (ICP-AES). In addition, As was analysed by hydride generation and Hg by cold vapour generation using ICO-AES.
ANALYSIS OF HYDROCARBONS IN SEDIMENTS
Two 10 g samples of sediment from each site were pooled and two such samples were prepared, resulting in duplicate 20 g samples for further analysis. After each sample was extracted with DCM/acetone, half the extract underwent GPC and florisil cleanups and analysis for PCBs by gas chromatography. The remaining extract was reduced and processed further before being screened for hydrocarbons, using ultraviolet fluorescence analysis (UVP). Gas chromatography-mass spectroscopy (GC-MS) was used to determine n-alkanes and total hydrocarbons (THC) from the reduced hydrocarbon fractions.