Although the Southern Ocean environment is relatively unaffected by human activities, the development of fisheries, growth of tourism, and the construction and expansion of coastal stations and facilities to support research are changing the pristine conditions of Antarctic marine ecosystems. A number of studies have reported the occurrence of a contaminated halo around point sources on the Antarctic shoreline. In most cases concentrations of metals and other persistent contaminants rapidly decrease within a few hundred metres of sources, and measured concentrations are often much lower than those deemed to be toxic for marine organisms. In all scientific stations, fossil fuel hydrocarbons, oil and greases are widely used to generate electric power and for heating and transportation. Hydrocarbons, particularly polycyclic aromatic hydrocarbons (PAHs; persistent toxic substances which are produced through hydrocarbon fuel spillage and as unintended by-products of combustion), are the most widespread environmental contaminants in coastal marine areas near the larger and/or long-inhabited Antarctic stations. Hydrocarbons in the environment occur as complex mixtures, and it can be difficult to detect low-level anthropogenic contamination in Antarctica, because many compounds are also found in biogenic materials. Research by Cripps (1989) in Antarctic remote marine areas and in those affected by human coastal settlements revealed that methods used to assess the possible anthropogenic input of hydrocarbons were rather inconsistent. These methods assumed that organisms synthesise a range of n-alkanes dominated by compounds with odd numbers of carbon atoms, and/or that values greater than unity for the pristine/phytane ratio indicate the absence of petroleum. Even PAHs formed during the pyrolysis of organic materials cannot be considered reliable tracers of anthropogenic input, because the combustion of petroleum may result in high levels of alkanes and low levels of PAHs with three or more rings in their structure. Moreover, PAHs in the Southern Ocean are also produced by microorganisms (Cripps 1989). The author suggested that the identification of anthropogenic input in Antarctic coastal ecosystems should be based on the quantification of all compounds against a well-defined baseline; the source of pollution can then be estimated from hydrocarbon distribution patterns. In addition to the difficulty in discriminating between natural and anthropogenic hydrocarbons, data on PAHs and n-alkanes in the Southern Ocean environment are extremely variable, and this variability is at least in part due (Ehrhardt et al. 1991) to the wide variety of adopted analytical methods (e.g. spectrofluorometry, HPLC, capillary GC, GC/MS).
In addition to petroleum hydrocarbons, some studies have investigated the concentrations and distribution in coastal marine sediments of other lipid compounds such as sterols and fatty acids (e.g. Smith et al. 1986; Venkatesan and Kaplan 1987; Weber and Bigeco 1990; Green et al. 1992; Venkatesan and Mirsadeghi 1992; Green and Nichols 1995). In temperate regions, sterols such as coprostanol and epicoprostanol are often used as tracers of human faecal waste. However, in Antarctica these compounds are also produced by seals and other marine mammals (Venkatesan et al. 1986).
Despite difficulties in discriminating between natural and anthropogenic sources of hydrocarbons and sterols, clear evidence of local seawater and sediment contamination by human activities has been reported in areas located near long-inhabited research stations or land-based whale processing plants. Although the results of environmental studies in the Ross Sea Region, Palmer Peninsula, Davis Station and sub-Antarctic islands will be reported in this chapter, the reader should refer to Kennicutt and Champ (1992), COMNAP-AEON (2001), and UNEP (2002a) for more comprehensive reviews.
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