Sunday, October 29, 2000

Waste not wanted

Published in the Antarctic Sun

McMurdo Station is the largest human settlement on the continent of Antarctica. More than
1,000 people will call it home this summer.

It’s an around-the-clock operation that generates sewage 24 hours a day. That waste is piped into the ocean less than 200 feet from the shoreline.

Two researchers are studying the impact the sewage outflow has on the McMurdo Sound ecosystem and on the quality of drinking water at the station.

John Lisle and Jim Smith are examining samples of ocean-floor sediment, the seawater, Weddell seal feces and McMurdo’s drinking water for evidence of human bacteria and viruses.

The first two are primary sources for a baseline indicator of how much pollution the sewage is introducing into the slow-moving ocean off McMurdo Station.

Seal feces help show the degree to which human bacteria have become part of the ecosystem, possibly causing disease in the seal population.

The drinking water studies are the first to test for viruses in McMurdo’s fresh water supply. The station’s water is regularly tested for bacteria and other contaminants, including lead.

The three major indicators the pair are looking at are fecal coliform bacteria, a common indicator of water quality used in judging safety of beaches and shellfish, clostridium perfringens, a bacterium associated with human sewage, and human enterovirus, which is found in human
feces.

Seal exposure
Lisle and Smith will compare the genetic material in bacteria in sewage and in similar bacteria in seal feces to see if the human bacteria are exchanging genetic information with bacteria in seals.

“Nobody knows if seals normally have clostridia,” Lisle said. He said they are also trying to find some seals that would not have been exposed to human waste, to give them a baseline level of clostridium bacteria in seal feces.

They hope to learn whether human diseases are being transmitted to the seals.

Two teams of researchers studying Weddell seals in McMurdo Sound are helping the pair by collecting samples of seal feces.

Outfall sampling
Science support diver Rob Robbins is collecting samples of water and the ocean floor around the sewage outfall.

Previous work has shown clostridia in sediment layers containing fecal coliform, and defined the physical extent of the pollution from the sewage outfall.

One of the problems was the concentration of waste in a location where the water doesn’t do much to dilute it.

“There aren’t very high current speeds here , ’’Smith said.

The end of the pipe, Robbins said, is 180 feet offshore in an area where the bottom is 60 feet deep. The pipe is raised four feet off the sea floor.

Since the new Crary aquarium was built five years ago, it flushes 250 gallons of cold seawater through the system each minute, Robbins said.

It used to be that the pile would grow over the course of a season to the height of the pipe. Now, Robbins said, with the increased flow from the aquarium in Crary, the waste has spread more thinly over a large area.

“Now it’s this huge field of effluent. It’s mostly poop out there,” Robbins said.

“Most of the pieces are about as big as your fingernail.”

Robbins talked about the spiny sea urchins that like to try to camouflage themselves with debris from the ocean floor.

Normally, they use other animals or bits of coral or other normal sea-floor debris. Near the outfall, though, Robbins said, “You see them with pretty interesting things.”

“I like diving at the outfall,” Robbins said. “You see things you’d never see anywhere else.”

Drinking water quality
The sewage plume extends beyond the intake for McMurdo’s water supply, but this has not been a problem in the past.

“The drinking water quality’s always been fine,” Smith said. But they are testing the water in a new way.

“This is the first time that viruses have been looked at,” Lisle said.

Both are clear, though, about the outfall’s role in transmitting contagious disease on the station.

“You can’t get the Crud from the sewer,” Smith said.

The samples of drinking water will be sent to the University of Arizona for analysis of viral presence; the results will not be available until the scientists return home.

Sewage treatment
“With the Antarctic Treaty, all the treaty signers are held to various standards for pollution and waste,” Smith said.

Some Antarctic bases do treat their waste already, including an Australian base, Smith said. New Zealand is planning to build a sewage treatment plant at Scott Base. McMurdo’s current macerator system meets the treaty requirements.

“Doing sewage treatment down here is a real challenge,” Smith said. Other places, he said, use big lagoons or oxidation ponds.

“ You can’t have that here. It’d just freeze solid,” he said.

Blasting began last week for McMurdo’s new sewage treatment plant, which will be running in 2003, said NSF facilities manager Frank Brier. The sludge from the plant, Brier said, will be sent back to the U.S. for disposal. The water leaving the plant will be treated to kill viruses and bacteria to prevent further pollution of the ocean.

“What is discharged (from the plant) is not drinkable but it’s clean,” Brier said.

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