Alaska's abandoned copper mines leave a mark

A century after copper mining began in Prince William Sound southeast of Anchorage a team of scientists is analyzing the region's environment to find out if metals are having an adverse effect. Not all the results are in yet, but in some places water quality is lower than it should be, LeeAnn Munk said in a presentation to the Alaska Miners Association in Anchorage Sept. 14.

Munk, an assistant professor of geological sciences at the University of Alaska Anchorage, has a doctorate from Ohio State in environmental geochemistry and has been in Alaska for just over four years. She and colleagues from the U.S. Geological Survey visited three locations in Prince William Sound: the sites of the former Beatson, Ellamar and Threeman mines. There were 24 copper mines in this region in the early 20th century, but Beatson - on Latouche Island - was by far the largest, accounting for 90 percent of the 5.8 million tons of ore that was mined.

The Beatson copper mine started shipping ore in 1904. From 1915 until its closure in 1930 the mine was operated by Kennecott and employed up to 300 people. The Good Friday Earthquake of 1964 that devastated Southcentral coastal Alaska raised Latouche Island an average of nine feet and moved it about 60 feet to the southeast. As the beach is raised, the mine tailings are not exposed to seawater and there is probably not much chemical impact on the near-shore environment, Munk said, although there may be a biological impact.

Sampling began in 2002

The scientists have been taking samples offshore and onshore since summer 2002, Munk said. On the water they use a chartered fishing boat equipped for fieldwork and a remotely operated vehicle that takes samples below sea level. "The overall goal is to look at what sort of flux of metals like copper, zinc, lead in some cases, and other trace elements are actually being weathered out of the old mine tailings as well as the waste rock, as well as the naturally occurring bedrock and the ore that may still exist that is unmined," Munk told miners.

One of the main questions for the scientists is which metals are being transported from the terrestrial environment (the land and the streams on land) to the near-shore environment and to seawater, and in what quantities.

"You can have metals dissolved in water, but also transported on particulate matter, suspended sediment, so we look at those two different components in our sampling," Munk said. "We also look at secondary precipitates ... A lot of the metals actually end up in that material, rather than dissolved in the water."

Focus this year on foot chain

This summer there has been a particular focus on whether the metals are getting into the food chain via the eelgrass and invertebrates. The small number of people who live in or vacation in the vicinity of the abandoned mines like to harvest the clams and mussels. "We also have a microbiologist now who is helping us look at what microorganisms might play important roles in the weathering of the waste rock and the tailings, and what role the microbes have, and this is kind of a new area in environmental geochemistry itself, so we're really happy to have her working with us," Munk said.

More iron than copper or zinc can be found dissolved in the water at the Beatson site, which may be due to the degrading scrap iron that is lying around, including old barrels and machinery. People who have cabins in the area ask Munk if they can drink the water, and she refers them to Environmental Protection Agency water quality standards. "In many cases, depending on where you are in the stream, there are high levels (of metals) that exceed what the EPA recommends for drinking water quality standards," she said. The highest concentrations of metals are in the sediment and could be harmful to invertebrates.

Lake popular with wildlife

At Beatson the glory hole has become a lake that is popular with bears and seagulls. At Ellamar the ore was mined below sea level and the glory hole is now submerged. Munk and her team sent a camera down there and found that local residents had been dumping their garbage in it, including a bike.

"Ellamar is a little bit different from Beatson because the beach itself is actually made up of massive sulfide pieces of rock and waste rock," Munk said. The scientists did an experiment to find out if there was any change in the chemistry of the water during low tide and high tide, to see if there was a different effect on how the tailings were oxidized in fresh water and salt water. They observed unsightly accumulations of "yellow boy," an iron sulfate precipitate that forms in acid mine drainage environments. The pH of the water was about 3, much lower than at Beatson, and it tended to decrease at low tide.

Threeman, just south of Ellamar, is the smallest of the sites. Tailings are also located on the beach, which is at the top of a steep slope. A rare purple, sulfur-loving bacteria has been found here, and the microbiologist is investigating it. No data has been obtained from Threeman yet, as the scientists visited it for the first time this summer.

Munk thanked the AMA for their support for UAA's geology major, which was approved last year. The university already has 40 students in the program, she said.