/ ^Vv

Fig. 11.11. Predicted oil-slick trajectories for hypothetical spills sited on the Eastern (A), Central (B) and Victoria Land Basins (C) of the Ross Sea. During the short, open-water summer season, most rocky shores and beaches, many of which are important penguin rookeries, of Ross Island and adjacent Victoria Land coast could be under threat, by a spill comparable in magnitude to IXTOC 1. The strong gyral circulation also spreads locally-derived litter northwards along the coast as shown (Based on Gregory, 1982, fig. 3; Gregory et al., 1984a, fig. 6; Cook and Davey, 1984, fig. 1).

Antarctica, it is widely acknowledged, is the most severe, physically and technologically demanding and environmentally hazardous place on earth, in which to conduct hydrocarbon exploration and exploitation. Nevertheless, seismic surveying and the consequential exploratory drilling for identified targets in the Ross Sea could take place today using currently available technology (Anonymous, 1977; Hodgate and Tinker, 1979; Zumberge, 1979, 1982; Burroughs, 1986). Successful exploitation will require costly evolution and adaptation of technology developed for Arctic conditions (e.g., Roots, 1983), although conceptual feasibility has been demonstrated (Splettstoesser, 1979; Sanderson, 1983; St. John, 1986). There is an evolving consensus, however, that, because of economic constraints alone, hydrocarbon exploitation is unlikely in the foreseeable future (cf. Holdgate, 1984; Garrett, 1985).

Because of the great water depths of the Ross Sea (e.g., 200-900 m over prospective parts of the Victoria Land Basin) and the short open water season of 3 months or less (Keys, 1984), it has been suggested that the only sensible long-term option for oil production would be a subsea well completion (Sanderson, 1983). It would need to function without surface maintenance for at least nine months or it could be serviced by submarine — a technology awaiting development. Any subsea completion and pipeline(s) would need to be buried some 5-10 m for protection against iceberg scour. Sanderson (1983) considered that the most likely "export" method would be by seafloor storage and large icebreaking tankers (VLCC) capable of coping with ice conditions year round. Another option could be large submarines (McLaren, 1984). Alternatively, oil could be pipelined to a shore storage facility to await onward delivery.

Environmental and Pollution Aspects

Crude and processed oils vary greatly in their physical and chemical properties, although in both the lighter and more soluble aromatic fractions are highly toxic to marine life. Even in cold waters, spreading of oil as ever-thinning films on the sea surface is rapid, with slicks moving at some 60% of water current rate and 3% of wind speed. The fate and behaviour of oil spilled in cold (Arctic) ice-infested waters have been reviewed by several authors (e.g., Weller, 1980b; Nelson-Smith, 1982; Hume et al., 1983; Weeks and Weller, 1984; Mackay, 1985; Bobra and Fingas, 1986) and amongst the more important processes identified are: evaporative ageing and weathering, mechanical and physical dispersal, dissolution and emulsification, sea-ice and shoreline inter-actions and microbial activities together with seasonal factors and amount of oil that has been spilled. Although difficult to quantify, it is accepted that rates of natural degradation and decomposition are substantially slower in polar environments than they are in temperate ones. Conclusions from the extensive and important Canadian contributions to the study of oil spills in northern high latitudes (e.g., Sergy and Blackall, 1987) are not entirely relevant to the Ross Sea (Holdgate and Tinker, 1979; Keys, 1984). As examples, the Ross Sea pack-ice is lighter and there is less, thick multiyear ice than that which is experienced in the Arctic (Mitchell, 1983), water depths at likely offshore hydrocarbon prospects are too deep for the bottom-founded structures typical of the Beaufort Sea and icebergs are more numerous and larger.

Many authors have addressed the possible environmental consequences and issues likely to arise from the exploration for and exploitation of hydrocarbon resources lying beneath Antarctica's continental shelf (e.g., Elliot, 1977; Dugger, 1978; Holdgate and Tinker, 1979; Zumberge, 1979,1982; Brewster, 1982; Gregory, 1982; Gregory and Kirk, 1983; Holdgate, 1983,1984; Sanderson, 1983; Keys, 1984; Joyner, 1985). The environmental factors and problems identified, which are many, have been summarized by Holdgate and Tinker (1979) and repeated elsewhere (e.g., Holdgate, 1983, 1984). They are presented in Table 11.3, and only some aspects of particular relevance to the Ross Sea are developed in the following discussion. In a review of Southern Ocean pollution, some readers may consider these remarks unnecessary and little better than informed speculation. Others may be more concilliatory viewing them as anticipatory, having a forecasting role, and a necessary part of establishing the planning criteria should hydrocarbon exploration and exploitation ever eventuate around the region.

Shore Line Impact

Gregory (1982) suggested that much of the coast around the Ross Sea could be at risk following a large tanker accident, pipeline rupture, or well head blowout comparable in magnitude to the IXTOC 1 incident in Campeche Bay, Gulf of Mexico (cf. Fig. 11.11). This was the largest spill in history releasing > 4,000,000 tonnes of oil into the sea between June 3, 1979 and March 23, 1980, with impact reaching Texas beaches over 800 km from the spill site. Ross Sea impact potential would be greatest during relative ice-free periods of the brief summer season (December-March) and environmental response determined by hydrocarbon type and weather conditions at the time, as well as shore-line character and processes. Shores of the region are dominated by high ice cliffs (Gregory et al., 1984a; Kirk and Gregory, in press). Seasonally variable landfast sea ice may comprise more than 90% of the effective shore (Fig. 11.12). Ice-free or bare rocky shores comprise little more than a quarter of the coast (Fig. 11.13). The coastal categories of high ice cliffs, high rocky cliffs, low partially ice-covered rocky shores and beaches together with fast ice, identified in the mapping programme of Gregory et al. (1984a) do not fit into a hierarchy of oil spill persistence or physical sensitivity indices of the kinds favoured for mid-latitude coastal landforms (e.g., Gundlach and Hayes, 1978; Michel et al, 1978; Gregory, 1981).

Furthermore, the Arctic experience with retention indices (Nummedal, 1980) and the breakdown of major shore type into several subdivisions (e.g., McLaren, 1980; Owens et al., 1981; Sempels, 1982; Welch, 1984) is inappropriate because coastal landforms of protected low energy environments, such as marshes, lagoons, broad intertidal mud and sand flats, vegetated and non-vegetated low banks and bluffs or cliffs in weakly consolidated materials, have no expression around the Ross Sea.

From observations reported widely in the literature, it has been concluded that high ice cliffs and other permanent and seasonal ice shores around the Ross Sea

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