Ocean depths lure mining companies
"In the depths of the ocean, there are mines of zinc, iron, silver and gold that would be quite easy to exploit," said Captain Nemo, hero of Jules Verne's Twenty Thousand Leagues Under the Sea, in 1870. Now 21st-century technology is confirming his statement, as mining companies, spurred by high commodity prices, prepare to extract metal ore from rich deposits more than a kilometre under water.
The Euroscience conference in Munich heard yesterday that science and technology had combined to make it realistic for the first time to exploit minerals deposited on the seabed in volcanic areas known as ocean ridges, which typically lie 1km-2km below the surface. They are rich in zinc, iron, silver and gold as well as copper and lead.
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Steven Scott, a seabed geologist at the University of Toronto, said two marine mining companies were exploring deep ocean mining prospects. Nautilus Minerals - based in Vancouver, which shares its name with Captain Nemo's submarine - is focusing on the Manus basin near Papua New Guinea, while Neptune Minerals, based in Sydney, concentrates on an area off the coast of New Zealand's North Island.
The prospect has evoked "knee-jerk" opposition from some environmentalists, according to Prof Scott. "There is understandably going to be legitimate concern from many in the public," he said, although he believes deep ocean mining would be less damaging overall than current terrestrial extraction.
There is no acid mine drainage, since acids are neutralised immediately by alkaline seawater. The operations would not touch the active hydrothermal vents, known as "black smokers", which boast extraordinary colonies of submarine animals and plants that have evolved to thrive in extremes of temperature, pressure and chemical concentrations. And the sulphide mineral deposits lie directly on the sea floor, so there would be no excavation and waste rock piles.
Other seabed researchers at the Munich conference agreed cautiously with Prof Scott. Colin Devey, of the Leibniz Institute of Marine Sciences in Germany, said: "The ocean ridges are very active volcanic landscapes. For me that is not a fragile environment. The creatures there have adjusted to life on the edge.
"But there is some difference of opinion within the scientific community," he added. He also runs InterRidge, an international organisation of ocean ridge researchers.
The metal ore would be pumped as slurry up from the seabed to the surface, said Prof Scott. Technology would be brought in from the coal mining and offshore oil industries - and from the abortive attempt in the 1970s and 1980s to extract manganese nodules from the ocean floor 5km deep.
海底采矿将成现实”
“海洋深处有锌、铁、银和金矿，开采相当容易，”儒勒?凡尔纳(Jules Verne)小说《海底两万里》中的主人公尼莫船长(Captain Nemo)在1870年如是说。如今，21世纪的技术正在证实他的这一断言，因为在大宗商品高价的激励下，矿业公司准备从水下逾1公里深处的丰富矿藏中开采金属矿物。
在慕尼黑召开的欧洲科学(Euroscience)大会上，昨天有人发言表示，海洋科学和开采技术的结合，已使开采储存在海床上火山区域的矿物首次成为可能。这些火山区被称为大洋脊(ocean ridge)，一般距离海洋表面1至2公里，它们蕴藏着丰富的锌、铁、银、金、铜和铅。
多伦多大学海床地质学家史蒂芬?斯科特(Steven Scott)表示，2家海洋矿业公司已在积极探索深海采矿前景。
总部设在温哥华的Nautilus Minerals公司在多伦多证交所上市，公司名称与尼莫船长的潜艇同名。该公司正将重点放在巴布亚新几内亚附近的马努斯(Manus)盆地上。而总部设在悉尼、在伦敦上市的Neptune Minerals，则把精力集中在新西兰北岛海岸附近的一片区域。
斯科特教授称，海底开采的前景，引发了一些环保人士的“本能”反对。“公众将会出现一些正当的担忧，这可以理解，”他说，不过他相信，深海采矿将比陆上开采造成的危害小。
海底开采不存在酸矿排放问题，这是因为酸性物质已被碱性海水立即中和。开采作业不会碰及被称为“海底黑烟囱”的活性热液喷溢口，这些喷口寄生着千奇百怪的海底动植物群落，它们已进化到能在极端条件下繁衍兴旺。而硫化物矿藏直接坐落在海床上。
参加慕尼黑会议的其他海床研究人员谨慎同意斯科特教授的观点。德国莱布尼茨海洋科学研究所(Leibnitz Institute of Marine Sciences)的科林?德维(Colin Devey)表示：“大洋脊是一片活火山……不是脆弱的环境。那里的生物已适应在极端环境下生存。”
