Contaminants in marine sediments, sponges and bivalves from McMurdo Sound, Antarctica

Brief description

SEDIMENT SAMPLINGFour 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 CLAM AND SPONGE SAMPLINGFive 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 SPONGESAfter 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 SEDIMENTSTwo 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. This research was undertaken to compare the concentrations of contaminants in the vicinity of the scientific bases, Scott Base (NZ) and McMurdo Station (US) with less impacted sites at Cape Armitage, Turtle Rock and Cape Evans. Sediment samples were analysed for total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH) and the trace metals (Cu, Zn, Cd, Pb, Hg and As). Sponge and clam tissues were analysed for the presence of trace metals only. TBT contamination of sediments from these sites is described in the metadata record:Tributyltin (TBT) in marine sediments from McMurdo Sound, Antarctica

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Maintenance and Update Frequency: notPlanned

Statement: Statement: Trace metal extraction and analysis:Sediments were digested using the method described in:Kwiecien W (1990) Silicate Rock Analysis by AAS. School of Geology, Queensland University Technology, Brisbane.Clam and sponge samples were digested using the method described in:Thompson M, Walsh JN (1989) Handbook of Inductively Coupled Plasma Spectrometry. Blackie & Son Ltd, London, pp. 155-156.A Varian Liberty 220 inductively coupled plasma-atomic emission spectrometer (ICP-AES) was used for metal analyses.The method for analysis of Hg followed:Adair BM, Cobb GP (1999) Improved preparation of small biological samples for mercury analysis using cold vapour atomic absorption spectroscopy. Chemosphere 38, 2951-2958.Recoveries for each batch of samples were assessed against certified reference materials from the National Research Council of Canada (DOLT 1 and 2976 Mussel Tissue for bivalves and sponges and MESS-2 for sediments) and fell within the certified range for all elements analysed.Hydrocarbon, PCB and PAH extraction and analysis:The samples were extracted by a NATA accredited laboratory (ALS Environmental, Sydney). Extracts underwent GPC (USEPA Method 3640) and florisil (USEPA Method 3620) cleanups and analysis for PCBs by gas chromatography-electron capture detection (GC-ECD) (USEPA Method 8081/8082). The detection limit for total PCBs reported by ALS Environmental was 5 mg/kg dry weight.The instrument used for ultraviolet fluorescence analysis was calibrated against a light Arabian crude oil standard. Gas chromatography-mass spectroscopy detection (GC-MS) was performed using an Agilent 6890 GC/5973 MSD system, with pulsed pressure splitless injection into an HP-5MS capillary column (30 m, 0.25 mm, 0.5 mm).The method for determination of n-alkanes and total hydrocarbons (THC) was based on GC-MS-selected ion monitoring (SIM), targeting ions m/z = 57, 71, 83 and 85. Alkanes were quantified using external standards over the range of n-dodecane (C12) to n-hexatricontane (C36). A GC-MS-SIM program was used to monitor a selection of m/z ions characteristic of 265 parent PAHs and one to four carbon alkylated oil-derived PAHs over the naphthalene/biphenyl, phenanthrene/anthracene, dibenzothiophene, chrysene/benzanthracene, pyrene/fluoranthene series, plus nine higher molecular weight combustion-derived PAHs. These were quantified using external standards for parent PAHs and at least one alkylated PAH within each group. A suite of characteristic triterpane (Tm, Ts, C29, C30 through C35 hopanes) and sterane (alpha beta beta-C27, C28 and C29 R&S isomers) petroleum biomarkers (Peters and Moldowan, 1993) were quantified using d4-stigmastane as an external standard. Final quantification was achieved following the application of reported relative response factors (Geosciences-Australia, 1996).Peters KE, Moldowan JM (1993). The Biomarker Guide: Interpreting Molecular Fossils in Petroleum and Ancient Sediments. Prentic Hall, New Jersey, 363 pp.Geosciences-Australia (1996) National oil spill identification database, GPOBox 378, Canberra, Australia 2601.

Notes

Credit
Negri, Andrew P, Dr (Principal Investigator)