Annex III to The Protocol on Environmental Protection to the Antarctica Treaty requires “Past and present waste disposal sites on land and abandoned work sites of Antarctic activities shall be cleaned up by the generator of such wastes and the user of such sites.” Two exceptions are contained in Annex III: historic sites and monuments and where “removal by any practical option would result in greater adverse environmental impact than leaving the structure or waste material in its existing location”.
To date, environmental remediation efforts in Antarctica have focused on terrestrial sites and have encompassed clean-up of former waste sites, removal of disused infrastructure/debris and some removal/remediation of contaminated soils. It is estimated that 1-10 million m3 of contaminated soils may exist in Antarctica . As sites requiring remediation are often associated with present or historic research stations, they are preferentially located in coastal ice-free areas, which represent only 0.18% of the continent and include important habitats for Antarctica fauna and flora . While contamination is known to exist at marine sites within Antarctica , few marine remediation efforts have been undertaken. National programmes have cleaned up former waste sites and removed unused infrastructure on land but overall remediation efforts in Antarctica have been limited since the Protocol entered into force [2, 4].
A modicum of success in the remediation of contaminated sites has been achieved by some national programmes. Perhaps the best documented and most holistic and integrated remediation efforts are those of the Australian Antarctic Program at Casey Station, which began in the 1990s (Figure 1).
In addition to physical removal of waste material and contaminated ground, investigations of the water and soils have characterized the levels and patterns of contaminants and their movement through the local environment . The responses of local biota to contaminants and the efficacy of remediation techniques in the Antarctic environment also received study [5-7]. Other national programmes, including the United Kingdom (Figures 2 and 3), Japan, Argentina, Brazil and Uruguay, have undertaken remediation projects .
The work required in the combined New Zealand/United States clean-up of the Cape Hallett Station (which was abandoned in the early 1970s) illustrates the challenges of cleaning up a major scientific station in a remote location. After many years of modest clean-up attempts, and a great deal of planning, the final clean-up and removal effort took three dedicated field seasons. Its proximity to a penguin rookery indicates that where wildlife may come into direct contact with remaining debris and possibly contaminated soils, it is important to consider further monitoring after clean-up has been completed (Figure 4).
Remediation efforts in Antarctica to date have been hampered by a number of factors. Unlike lower latitude regions and some Arctic countries, Antarctica lacks comprehensive environmental regulations. The Protocol does not establish overall remediation guidelines for chemical contamination, specific clean-up protocols, and there are no penalties for pollution or mechanisms to enforce land reparation as there are elsewhere in the world. Most Consultative Parties have their own environmental regulations and remediation criteria. These often take the form of soil and water guidelines that are used as the first trigger in determining whether an area may be considered contaminated. However, trigger levels differ considerably between countries  and the Protocol does not define what contamination levels should trigger remediation activities or specify an enforcement mechanism other than through Annex VI on Liability. This lack of agreed detail has slowed remediation efforts to date.
There are significant gaps in the scientific knowledge relating to remediation in the Polar Regions. In particular there is a paucity of ecological risk assessment data relevant to the Antarctic environment that can be applied in determining clean-up criteria in remediation programme design. There is limited information for bioaccumulation or toxicity of contaminants in polar species. While toxicity tests have been used widely in temperate regions to relate concentrations of environmental contaminants to biological effects, few studies on polar species have been published. The scarcity of such studies makes it impossible to know whether environmental guidelines determined for lower-latitudes are applicable to terrestrial and marine environments in Antarctica [8, 9, 10].
Petroleum hydrocarbons appear to be the main environmental contaminant in Antarctica on land and may persist in Antarctic soils for long periods . To-date the dominant remediation practice has been to mechanically remove as much fuel contaminated soil, including overlying snow/ice, as is practical. The material has often been shipped off-continent for disposal. However, this expensive practice may be replaced by alternative methods like bioremediation, currently under test at several sites. Additional scientific research on the abiotic and biotic effects of hydrocarbons in Antarctica is still required, including a better understanding of the processes, rates and pathways of hydrocarbon migration through the continent’s soils . Bioremediation is being actively studied to provide an in situ option to shipping contaminated soils off the continent [2, 12]. Polar bioremediation has been recently reviewed [13, 14] and Antarctic efforts should be informed by experiences from the contaminated Arctic .
Although clean-up is a requirement of the Protocol, taking action will depend upon the individual interpretation by a specific Party as to whether or not greater environmental harm might result. This introduces variability in approach, which is not helped by the lack of any internationally agreed criteria. If the remediation process is considered likely to cause more damage than leaving the site alone then remediation is not required . The extensive waste debris field and polychlorinated biphenyl (PCB) contaminated sediments in Winter Quarters Bay adjacent to McMurdo Station are currently contained in a sea floor depression. This is an example where, to date, the waste site has not been removed, but is monitored to determine dispersal, due to concerns that attempts to recover the polluted material would cause wide-scale distribution of the sediments with potential environmental impacts into undamaged areas .
In assessing remediation options, the operational feasibility of the proposed remediation must also be considered . Factors that must be taken into consideration include: whether the remediation can be undertaken safely both for people and for the environment, the accessibility of the area requiring remediation and the financial cost. To provide guidance in addressing environmental requirements, and in particular relating to Annex III to the Protocol, the Committee for Environmental Protection (CEP) produced a Clean-Up Manual in 2014. The manual focuses on practical guidance on the repair and remediation of past waste disposal locations, abandoned work sites and other sites contaminated by fuel or other hazardous waste spills.