Mine, All Mine
First discovered in 1979, hydrothermal vents, or black smokers, sit along volcanic mid-ocean ridges and subduction zones--areas where tectonic plates of the earth's crust slowly spread out or push into one another, melting rock below the seafloor. Sometimes seawater percolates downward, superheats, then jets back out, often laden with dissolved minerals such as copper, gold, silver, and zinc, which eventually pile up in the form of chimneys and mounds. Until now the formations--some of them lying 10,000 feet or more beneath the sea surface--have been thought too mysterious and remote for mining. They have remained the province of scientists fascinated with the unique heat- and chemical-loving creatures that haunt them--the source of life on earth, many believe. But with soaring metal prices, advances in seafloor mapping, and sophisticated new robotic technology, the riches that these areas contain may finally be within reach.
In recent years, mining outfits have staked out 900,000 square miles of vent fields and other potential deposits-a total area bigger than Mexico. James Hein, a senior scientist with the U.S. Geological Survey, believes mining will begin in the next two to three years. "You can't tell people in India or China, 'Sorry, you can't have telephones or cars or computers,'" he says. "The world market is going to get that metal from somewhere, and we are running out of it on land."
First in line for a working vent mine is Australia-based Nautilus Minerals, which for the past few years has explored the volcanically active Bismarck Sea, in the territorial waters of Papua New Guinea. Now Nautilus is about to request permits to mine a soccer-field-size lode 5,000 feet underwater; the company says the area contains almost two million tons of ore, including concentrations of copper six or seven times higher than most land mines. Nautilus hopes to be digging by 2010.
The site is seen as an economic and environmental test case. Steven Scott, a professor emeritus of geology at the University of Toronto who helped pioneer the study of vents, points out that underwater mining could be done "surgically" and so have some environmental pluses. Mining on land usually requires moving as much as seven tons of overlying rock for every ton of ore-and that ore is of lower grade to begin with. That means huge energy usage and waste generation, factors that could be cut by as much as 90 percent at a rich sea mine. Additionally, acid drainage from oxidizing waste rock would not exist undersea, because what little waste is produced would be neutralized by alkaline seawater. Nor would there be any need for new roads or towns; once a deposit is worked, the mother ship would just move on.
The negatives are mainly the huge unknowns regarding the biology and physics of vent systems and of the sea in general. Nautilus says it will mine only small "dead or dying" systems that are no longer hot spots for high-temperature vent fauna. But scientists say the company's initial site is still slowly leaking hot water, and a sizable volcano with active black smokers is less than a mile away. The smokers host dozens of specialized mussels, tube worms, shrimps, and primitive bacteria. The mine area itself--a forest of chimneys up to 35 feet high and six feet thick and mounds of fallen rock--is twice as rich in biodiversity. There are corals, barnacles, and snails, some of which may need that kind of habitat, says Cindy Lee Van Dover, a biological oceanographer at Duke University who assessed the site for Nautilus. Many of these species are new to science, and almost nothing is known about their biology or ecology. "If you take out one patch, it's probably no big deal," she says. "If you start in on a large scale and take out every patch across a region, it could be devastating."
Nautilus plans to rip out the top 40 feet or so of soft rock in baseball-size chunks with a gigantic robot like those used in coal mines, then pipe it up to barges for processing on land. But no matter how careful the company is, mining will almost certainly create sediment plumes that could travel tens or even hundreds of miles and smother filter-feeding organisms, says Chuck Fisher, a marine biologist at Pennsylvania State University. Currents could carry such plumes both sideways and upward, lacing mid-depth and surface waters with toxins or an overabundance of nutrients, which could upset coral reefs, clog the gills of fish, and harm creatures such as sea turtles.
Van Dover hopes that governments will wait at least five years for biologists to learn more before allowing widespread operations. Meanwhile, a few efforts to shield undersea deposits are underway. In 2003, for example, Canada placed the Endeavour vent field, a small Pacific system off Vancouver Island, off-limits. In 2006, Portugal did the same with the Lucky Strike system, near the Azores. But these sites are tiny-a few dozen square miles in the vastness of the seas."[We] do not have a very good record of regulating mining on land," says Wenceslaus Magun, an environmental activist in Papua New Guinea, "and may not have the capabilities to do so at sea."