Antarctic Footprint Clean-up Challenges - How A Remote Antarctic Base Clean-up Protected One Of Earth’s Clearest Lakes

The clean-up and site restoration of a New Zealand research station in Antarctica has provided valuable lessons on the challenges of contaminated sites, according to a study in the journal Polar Record, recently published by Cambridge University Press.

The study found that while tonnes of contaminated materials were removed from the former Vanda field station, some residual contamination still remained. However, the remediation of the site in Antarctic’s Dry Valleys, which had served as a research base for a quarter of a century, didn’t affect measurably the water quality of the area’s largest and deepest lake or the biological communities that colonised the station footprint.

There was no detectable human-induced environmental change to the pristine Lake Vanda following the decommissioning of the research station, conclude researchers from NIWA, Waikato and Canterbury universities, and Antarctica New Zealand. The successful site rehabilitation shows that in a harsh environment, amongst delicate ecosystems, it is possible to ensure minimal impact from the restoration of a contaminated site, says NIWA aquatic scientist Dr Clive Howard-Williams.

"Located in Antarctica’s largest ice-free area, the arid Dry Valleys, Vanda Station is one of the few research stations that have been decommissioned under more stringent Antarctic environmental standards. Neither minimizing human impact nor climate change may have been top-of-mind when construction commenced in 1968. The eight-building complex was built on a ridge 200m away from Lake Vanda, which has a depth of 78m and some of the clearest water on earth, with a unique warm bottom layer that is more saline than the Dead Sea."

The station facilities included a workshop, lab, generator room, huts for a dozen people, and a toilet above a removable drum, with a tractor hauling supplies and fuel from three helicopter landing areas to the station. The station was occupied every summer from 1968 (and even had staff year-round for three winters), hosting scientists, surveyors, maintenance staff, aircraft crews and VIPs. By the time it was closed in 1992, the site had hosted nearly 17,000 person-days - the equivalent of nearly 46 years. For a polar desert site, this is a substantial human footprint, says Antarctic inland water expert and veteran of more than three decades in the Dry Valleys, Waikato University’s Dr Ian Hawes.

It wasn’t the cumulative human impact that prompted the decision to close the research station, but the consequences of changes in climate.

"While the station was located 15 m above the level of the large, ice-covered Lake Vanda, over time more glacial meltwater flowed from Antarctica’s longest waterway, the Onyx River, into the closed-basin lake. So by 1991, it was just 2.5m below the site. The threat of inundation meant removing the buildings and structures became critically important. In 1991, the Antarctic Treaty Parties had just agreed on the Protocol on Environmental Protection to the Antarctic Treaty, which provides for the comprehensive protection of the Antarctic environment. Its Annex III on waste management and disposal outlines the requirements for the management of wastes associated with present and future activities. Annex III called for programmes to clean up existing waste disposal sites and abandoned work sites so long as their removal didn’t result in a greater environmental impact than leaving the structure in its existing location. It was decided that decommissions of the station would be compliant with the Protocol even though New Zealand did not implement the Protocol into domestic legislation until 1994 as the Antarctica (Environmental Protection) Act."

One concern was that compounds not normally found in the lake, such as organic phosphates, hydrocarbons, fats and soot, might contaminate Lake Vanda, says Professor Hawes.

"A site survey found soil contamination around the station and other locations with hydrocarbons and domestic waste, including high metal concentrations, and contamination associated with detergents, food scraps, packaging and fuels, particularly in the area known as Greywater Gully. If contaminants or nutrients were released into the lake, it could affect the unique microbial mat communities that grow on the floor of Lake Vanda .So, a great deal of effort was put into removing the most contaminated soils and groundwater before the site was flooded. To assess the effectiveness of the rehabilitation, these microbial mats have been monitored, along with levels of trace metals and nutrients in the lake water at the station site."

Rather than return the site to a pristine state, the plan focused on ensuring minimum impact on the lake ecosystem, ensuring that benefits outweighed the damage of remediation activities, says Dr Howard-Williams.

"The plan included excavating and removing the soils and contaminated groundwater, including lead-based painted rocks and fuel-splattered dirt, and returning the terrain to a more natural, pre-human appearance. Around 400kg of contaminated groundwater from the gully along with 7,000kg of soil were shipped back to Scott Base for treatment and disposal."

Results showed that while initial research suggested contaminants from the gully could potentially impact the lake’s ecosystem, 20 years after decommissioning and the complete flooding of the site, there was no evidence of contaminants entering the lake water and the microbial communities colonising the station site were not significantly different from those developing in uncontaminated areas.

Dr Howard-Williams says while recent guidelines on cleaning up contaminated sites in Antarctica outlined in the Antarctic Clean Up Manual are useful, challenges remain particularly when not much is known about the consequences of contamination of Antarctic ecosystems.

"It has been estimated that across Antarctica there may be around two million cubic metres of abandoned waste materials and hydro-carbon contaminated sediment. Effective remediation in Antarctica requires early planning, robust environmental baselines, and adaptive strategies grounded in research - recognising that full decontamination is rarely possible and must be balanced against the risk of further environmental harm. Despite the lack of comparable data, detailed clean-up guidelines, and contaminant baselines, Vanda’s clean up not only demonstrates New Zealand’s commitment to good environmental management, but it will also serve as an example to other countries involved in operations across Antarctica."

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