Issues Magazine

Sewage in Antarctica: A Drop in a Frozen Ocean?

Elephant seals on the beach at Davis come into regular contact with wastewater

Elephant seals on the beach at Davis come into regular contact with wastewater effluent. ©David Barringhaus/Commonwealth of Australia

By Jonathan Stark

It’s an unavoidable truth: wherever there are people there is poo. Approaches to the disposal and handling of sewage and wastewater depend on where you are. In Antarctica there are numerous challenges for sewage disposal.

Most Antarctic research stations are situated on the coast, including all three of Australia’s stations. The simplest solution to sewage and wastewater disposal in coastal regions around the world is discharge of effluents into the sea. But how is this regarded under the Antarctic Treaty, and what are the potential impacts of this activity? Is it just a drop in a frozen ocean?

Antarctic operations are conducted under the auspices of the Antarctic Treaty, and environmental issues are directed by the Protocol on Environmental Protection to the Antarctic Treaty 1991 (known as the Madrid Protocol). The Antarctic Treaty (Environment Protection) Act 1980 implements the Madrid Protocol into Australian law (see box, p.30).

Although the Madrid Protocol guides all activities in Antarctica, the actual management of wastewater by the many countries operating in Antarctica varies considerably, from no treatment to advanced sewage treatment methods.

Recently, the impacts of sewage have begun to receive more attention, as have treatment methods required to mitigate these impacts. Many countries have higher domestic sewage treatment standards for small communities than for similarly sized Antarctic research stations.

However, there is a growing movement towards regarding the obligations under the Madrid Protocol as the bare minimum, and several nations are applying the same requirements in Antarctica as they would to equivalent communities within their respective countries.

Australia has long been at the forefront of environmental stewardship and management in Antarctica. Its continued leadership is demonstrated in the decision to undertake the most comprehensive study of the potential environmental impacts associated with sewage and wastewater discharge into the marine environment in Antarctica, to better understand the impact of the outfall and help improve the management of sewage throughout Antarctica.

Assessing Impacts to Improve Management

The environmental impact of sewage discharged from Davis Station into adjacent coastal waters was the focus of an intensive scientific diving research program in Antarctica in the summer of 2009–10 by the Australian Antarctic Division (AAD). In 2005, the existing wastewater treatment infrastructure was removed because it was no longer suitable to deal with the effluent stream. Since then untreated, macerated wastewater effluent has been discharged to the sea at Davis.

The environmental impact assessment was instigated to guide the AAD in the choice of the most suitable replacement wastewater treatment facility at Davis and to support decisions that would enable Australia to surpass the standards set for the discharge of wastewaters in Antarctica in national legislation and international commitments, and to further Australia’s role as a leader in Antarctic environmental management and protection.

Under the Antarctic Treaty (Environment Protection) (Waste Management) Regulations, the AAD must demonstrate that disposal of the by-product of treatment of wastewater into the sea “is in a manner that does not adversely affect the local environment”. In addition, it requires that “all reasonable steps are taken to discharge the sewage or waste into the sea at a place where conditions exist for initial dilution and rapid dispersal of the sewage or waste”.

The Marine Environment at Davis

The marine environment in the region of Davis Station consists of shallow waters (2–40 metres) ranging from open coast to sheltered marine embayments. Deeper highly sheltered environments are encountered in the fjords of the Vestfold Hills region, but these were excluded from this survey because they are beyond the likely influence of the wastewater outfall.

Sea-ice cover is variable in duration, with some coastal areas having almost year-round sea-ice cover and others having open water for 3–4 months of the summer.

The Davis wastewater outfall is located on the southern side of the Davis wharf. The discharge point is approximately at the high tide level and 2 metres above the sediment/water surface. For most of the year the surrounding sea is frozen with a layer of sea-ice 1–2 metres thick. At the outfall the ice breaks out for a period of 3–4 months each summer between December and March.

The Davis beach and wharf area are important haul-out zones for moulting elephant seals in late summer (average 70–100 seals). Weddell seals and Adelie penguins are also frequently observed on the beach and in close proximity to the outfall. Elephant seals were observed wallowing in shallow water directly in front of the outfall on many occasions during this study.

Prior to this study there had been only limited investigation of the marine ecosystems around Davis, and very little was known about the distribution of sea bed habitats and their ecology. We aimed to survey and characterise the habitats, chemistry and biological communities at sites near the sewage outfall and compare these to control sites away from the possible influence of the sewage.

We sampled at a range of control locations both north and south of Davis Station in the same type of habitats encountered around the outfall. Habitats around the outfall (to a distance of 2 km) include shallow, fine to coarse sediments, shallow rocky reef, shallow mixed hard and soft substrata (mixes of cobbles, gravel, sand and mud), shallow macro-algal beds, and deeper depositional basins, slopes and plains dominated by finer sediments. Sites were surveyed around the Davis/Vestfolds region, primarily by divers from a small work boat, Pagodroma.

A site was defined as an area of approximately 50 metres radius around the work boat at anchor, as this was the area in which divers could easily and safely work. In each site a number of different tasks were performed:

• habitat surveys to determine the types of physical and biological habitats and their variation from site to site. Divers recorded the proportion of different substrata types (rock, sand, mud) and types of biological cover (seaweed and invertebrates such as sponges);

• photo surveys to collect detailed information on the seabed communities. A special frame with a camera mounted on it was used to take photographs of a fixed area of the seabed for analysis in Australia;

• sediment core collection for a range of purposes. The biological communities living within the sediment (small invertebrates such as worms, crustaceans, snails and bivalves) were examined. The types of species present and their abundance provide a measure of ecosystem health as certain types of communities are characteristic of polluted or disturbed sites. A range of chemical analyses were conducted on the sediment, including for metals, sewage biomarkers, chemicals, detergents and oils. Sediments were also analysed for microbial communities, which provide an excellent indication of the presence of sewage contamination; and

• collection of invertebrates and fish for several different studies related to the project.

For much of the survey period we had to navigate underwater in poor visibility due to the plankton bloom that occurs over summer, reducing water clarity to only a few metres of green soup. Davis can be a very unforgiving place to dive from a boat. There is very little shelter from winds as the coastline is low-lying and open. We had many days of marginal weather, where the winds were not too strong to prevent us from operating on the water but strong enough to make it very cold and unpleasant. However, Pagodroma had a small cabin, and once we got the heater working we could all crowd in and warm up between dives and munch on frozen sandwiches. The strong winds caused the boat to swing widely on its anchor, making it difficult for both the divers underwater and the tenders on the surface manning the umbilicals.

Our team consisted of six divers and associated support and research staff. In all we surveyed 30 sites, conducted approximately 2.8 km of habitat surveys, took about 2000 photos of the sea bed, collected more than 400 sediment cores and did 176 dives.

Wastewater Properties

The wastewater effluent had properties broadly similar to effluent in other parts of the world, with some notable exceptions. While some toxic contaminants – such as metals and persistent organic pollutants – were detected, concentrations were generally very low. The effluent was, however, higher than usual in nutrients and solids, probably due to the fact that it is significantly more concentrated than a municipal wastewater stream: water is in limited supply and its use is rationed (e.g. shower times are limited to 2 minutes) and there is no input of stormwater or runoff from rain into the system. Levels of microbiological faecal indicator bacteria (faecal enterococci and Escherichia coli) in station wastewater were typical of untreated human sewage. In laboratory experiments, the wastewater was found to be lethal to local marine invertebrates at dilutions as low as 3% in sea water over 14–21 days. The sub-lethal effects and long-term impacts of extended exposures were not investigated.

Dispersal and Dilution

The direction of primary current flow and effluent dispersal in summer was to the south-west along the coast. However, some effluent was retained around the wharf area and dispersed to the north, particularly on a falling tide. Faecal indicator bacteria were detectable approximately 1.5 km to the south, 1.25 km to the north and 100 metres to the west of the outfall. Wildlife in the vicinity of Davis beach can be expected to come in contact with wastewater-associated indicator bacteria at concentrations above the ANZECC guideline limits for human health for marine primary contact recreation (immersion, swimming etc.). Wildlife within approximately 50 metres of the outfall would be exposed to levels well above these limits.

There is evidence of accumulation of contaminants in marine sediments at sites within 1.5 km of the outfall. There are relatively low levels of chemical contamination, sewage biomarkers and relatively high levels of microbial indicators of sewage in sediments at sites in the immediate vicinity of the wastewater outfall and at sites to the south of the station in the direction of primary current flow.

While there is evidence for dispersal of wastewater, the rate of dispersal is insufficient to prevent accumulation of contaminants in local marine habitats. This indicates there is long-term potential for a build-up of pollutants in the local environment (metals, persistent organic pollutants, surfactants) and non-native bacteria.

Environmental Impacts

Deformities observed in tissues of local fish were consistent with exposure to contaminants present in wastewater. However, testing whether there is a causal relationship was beyond the scope of this study. The occurrence of disease, as indicated by cellular deformities in the liver and gills, was more severe and extensive in fish collected next to the site of wastewater discharge than in fish collected from other sites around Davis, demonstrating a significant impact on the health of fish at Davis.

There was no evidence of impacts on other components of the sea bed communities, which were similar at the outfall to those at reference locations. However, analysis of stable nitrogen isotopes indicated that sewage and associated contaminants are making their way into the food chain.

One of the most important findings was that genes encoding for antibiotic resistance have been introduced into the Davis marine environment, carried by non-native bacteria and taken up by a common filter-feeding mollusc. The impact of this gene pollution to the diversity and evolution of native Antarctic bacterial communities is unknown. These genetic elements now present in the Davis marine environment may also confer selective advantages to bacteria other than antibiotic resistance.

Environmental Risks

The environmental risks of greatest concern in this study include the introduction of genetic elements to the Antarctic environment (a discovery new to science) and the introduction of non-native microorganisms and disease.

Large migratory wildlife (seals and penguins) as well as marine organisms and fish come into regular contact with wastewater effluent at Davis. The potential pathological effects of such exposure were not examined in this assessment and are unknown, but the exposure of animals to concentrations of bacteria deemed of risk for human disease is expected.

This study found conclusive evidence of impacts as a consequence of wastewater discharge to the marine ecosystem adjacent to Davis Station. The nature of these impacts have important implications when considering the level of treatment appropriate for Antarctica.

There is evidence that the dispersal and initial dilution of wastewater is insufficient to prevent accumulation of low levels of contaminants up to 2 km away and to prevent exposure of wildlife to potentially harmful levels of contaminants. The rate of the dispersal process is unknown, but given the evidence for accumulation of contaminants in marine sediments around the outfall, it would be difficult to consider it rapid compared with the rate of delivery into the environment. The current location of the outfall near the wharf leads to retention and pooling of effluent in the wharf area on an outgoing tide, with some dispersal north along Davis beach.

Sewage Treatment Technology

Interpreting these findings is somewhat of a grey area. While it is clear that there are potential impacts on the local environment, this is the same situation almost all countries operating coastal Antarctic stations are facing. The impact of sewage in Antarctica is a relatively new issue, and prior to this work we had little understanding of the extent and nature of potential impacts at Australia’s stations.

Upon reviewing the findings of this study, the AAD has decided to pursue the world’s best practice in sewage treatment technology. It is currently working with scientists from around Australia to develop a treatment system that will treat water to a standard that is better than drinking water.

A Drop in the Ocean?

This Australian research and its outcomes reflect a significant shift in how environmental management is now regarded in Antarctica. It mirrors a general shift over the past 20 years in how we all view the environment as a society. While the impacts of this outfall may seem insignificant in the context of the whole of Antarctica – just a “drop in the ocean” – in reality it has potentially far greater consequence. Coastal ice-free areas are extremely rare in Antarctica, constituting less than 0.01% of the continent. These areas are where human activities (research stations) are concentrated and are also important habitat for wildlife, such as penguin, seabird and seal breeding sites, important moss and lichen “forests” and highly diverse shallow water marine ecosystems.

Thus any potential impacts in these areas can’t be considered as too small and localised to ignore. Australia’s leadership in environmental stewardship will ensure improved management of such issues into the future.