Making sure clean-ups don't add to problems

Human impacts research at Casey this year focused on developing procedures for monitoring the planned clean-up of Thala Valley tip and other decades-old Antarctic waste dumps. Australia is committed to cleaning up such past sites, but only if it can be done without causing more environmental disturbance. We are monitoring the Thala Valley site so we can detect any environmental changes that may be caused by the clean-up. Because most Antarctic waste tips are near the seashore monitoring will focus on marine impacts.

The proposed monitoring has three main components that will provide information at different time scales. Short-term monitoring will provide information as the clean-up operation progresses. New field techniques and tools for measuring run-off contaminants and for on-site chemical analysis will enable excavation and removal work to be modified if necessary. To cover for the chance of such 'snapshot' chemical monitoring missing peak periods of contaminant spread, small amphipod crustaceans in tanks fed with tip run-off water will serve as biological sentinels, observed for behavioural changes compared to amphipods in 'clean' control tanks.

In the final assessment and audit of the clean up, medium-term monitoring will confirm whether or not the work added to environmental impacts. This year sediment traps deployed in Brown Bay and elsewhere measured contamination carried into the sea during the normal summer melt. Traps deployed during the clean-up will show any changes in contaminant mobilisation during and after the work, while sentinel amphipods will be analysed for contaminants in body tissues. Other experiments will determine whether clean-up work causes changes in recruitment of nearby sediment-living animals, whose larval stages are particularly vulnerable to pollution.

Long-term monitoring will determine whether the effort invested in the clean-up creates significant and lasting environmental improvements. Our research indicates that Brown Bay marine life, adjacent to Thala Valley, is very different from that at other locations near Casey and that human activity is the most probable cause of these differences. However, we do not know whether removing the tip will change the biological communities and if they do, how long it will take. We will look for increases in the diversity of animals and plants living on the sea-bed near Thala Valley as an indicator that the community is recovering.

The three monitoring time scales are needed not just for practical information to guide the Thala Valley clean-up, but also for more general insights into human impacts in Antarctica. Antarctic environmental impacts are assessed against whether they are likely to be less than minor and transitory, but the meaning of this is not easily defined. The three levels of monitoring will allow assessment of how serious the impacts are (whether they are minor) and how long they last (whether they are transitory).

Martin Riddle, Human Impacts Program Leader, AAD