|Next: Marine and coastal areas
Freshwater and saline lakes of Antarctica are found mainly in coastal regions, and in ice-free areas such as the Larsemann Hills, Schirmacher Oasis, Bunger Hills and Vestfold Hills. Such areas are rare in Antarctica and are often foci for human activities. These lakes are fed by glacier melt streams and many are particularly susceptible to contamination from human activities in the lake basins. In addition to those in ice-free areas, small lakes on ice are often associated with melt water from nunataks in inland Antarctica, and large lakes occur under the ice sheet in the central regions. Some, such as Lake Vostok are very large. Their global significance lies in the fact that they have not been exposed to the atmosphere for the past 500 000 years, and they have not yet been drilled into. International codes for the exploration of these lakes are being discussed by SCAR.
While the scale of threats facing Antarctic inland waters is not as great as those of the Arctic, significant threats do arise from local human activity, particularly for lakes in ice-free areas.
In the Larsemann Hills, at least one lake has been seriously contaminated by activities from an adjacent base which used the lake for cooling the base generators and as a dump for kitchen and other waste (Ellis-Evans and others 1997). Several other nearby lakes are adversely affected by road activities with a poor prognosis for the future (Lyons and others 1997).
In the McMurdo Dry Valleys, there have been diesel spills on some of the icecaps of the lakes and (small) losses of drilling material and fluid into the lakes from operations associated with the Dry Valley Drilling Programme (Parker and Holliman 1978). Small amounts of radioactive isotopes have been released into some of the lakes from accidental spillage and by deliberate introductions such as iodine 35 for tracing water movements (Vincent 1996). Small-scale contamination from camp sites adjacent to the lakes occurred during the first few years of exploration of the Valleys.
At least one of the lakes on the Schirmacher Oasis, Lake Glubokoye, has been recorded as receiving high amounts of phosphorus from wastewater inflow from the Russian Station Novolazarevskaya, and both this lake and Lake Stancionnoye show the effects of human influence from their elevated ammonium concentrations. The long-term threats to these lakes may have diminished in recent years due to a reduction in scientific activities in the oasis area (Borman and Fritche 1995).
Lakes on the islands of the Antarctic Peninsula, particularly the South Orkney Islands, have undergone rapid eutrophication in recent years as a result of increasing populations of seals transferring marine nutrients onto their catchments. Other lakes in the more densely populated islands, such as King George Island, that are in close proximity to bases, may be used as drinking water, and supplies remain under threat of ongoing low-level pollution.
In the past decade, there has been a significant increase in awareness of the environmental fragility of the waters of the ice-free areas of Antarctica. An environmental code of conduct for science operations in the Dry Valleys had been agreed by New Zealand and the United States (Vincent 1996). This has been presented to SCAR for consideration for recommendation to all nations operating in ice-free areas (SCAR 1996b).
|Next: Marine and coastal areas