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

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

沉积物采样：本研究通过水肺潜水（SCUBA），于斯科特基地（SB1、SB2、SB3）周边3个点位、麦克默多站（MM-0、MM-1）周边2个点位、阿米蒂奇角（CA）、埃文斯角（CE）及海龟岩周边各1个点位采集沉积物样品。于每个采样点周边20米半径范围内、水深18至25米处采集表层5厘米沉积物，每个点位采集4份平行样品，所有样品均冷冻保存。后续样品经冷冻干燥与粗筛分处理。

蛤类与海绵采样：手工采集5只成熟软壳蛤（Laternula elliptica）并冷冻保存。同时采集3种海绵——Homaxinella balfourensis、Mycale acerata与Sphaerotylus antarcticus的4份平行活检样品，吸干表面水分后冷冻保存。蛤类软组织与海绵组织后续均经冷冻干燥并研磨处理。

沉积物、蛤类与海绵的金属元素分析：样品经消解处理后，采用电感耦合等离子体原子发射光谱法（ICP-AES）测定沉积物、蛤类与海绵样品中的总铜（Cu）、锌（Zn）、镉（Cd）及铅（Pb）含量。此外，采用氢化物发生法分析砷（As），采用冷蒸气发生法结合ICO-AES分析汞（Hg）。

沉积物中的烃类物质分析：从每个采样点取两份10克沉积物样品混合，共制备两份此类混合样品，最终得到两份平行20克样品用于后续分析。每份样品经二氯甲烷/丙酮（DCM/acetone）萃取后，取一半萃取液进行凝胶渗透色谱（GPC）与弗罗里硅土净化处理，再通过气相色谱法分析多氯联苯（PCBs）含量。剩余萃取液经浓缩与进一步处理后，采用紫外荧光分析法（UVP）进行烃类物质筛查。采用气相色谱-质谱联用法（GC-MS）对浓缩后的烃类组分进行正构烷烃与总烃（THC）含量测定。

本研究旨在对比斯科特基地（新西兰）与麦克默多站（美国）周边区域的污染物浓度，同时以阿米蒂奇角、海龟岩与埃文斯角作为受干扰程度较低的对照点位。沉积物样品的分析指标包括总烃（THC）、多氯联苯（PCBs）、多环芳烃（PAH）以及痕量金属（Cu、Zn、Cd、Pb、Hg与As）。仅对海绵与蛤类组织的痕量金属含量进行分析。上述采样点沉积物的三丁基锡（TBT）污染情况详见元数据记录：《南极麦克默多湾海洋沉积物中的三丁基锡（TBT）》