Gas pipeline route survey reveals effects of pollution on Baltic Sea bottom

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The murky sea bottom moves slowly on the computer screen, as if it were a mind-numbingly boring film. Suddenly one of the screens goes blank. Alexander Yevdokimov grabs the radio.
     "Attention bridge. Stop and move 15 metres back. The computer crashed."
     "OK", comes the answer in a crackly voice. On the bridge of the research vessel, the Pollux, a young woman grabs the steering column, and the hull of the vessel begins to tremble slightly from the sudden braking action. Greenland-born Vivika Brandt is the navigating officer of the Pollux.
     Yevdokimov is Lithuanian. The vessel has been hired by a Swedish research company, surveying the sea bottom for the Russian-German gas pipeline company Nord-Stream.
     An international team is studying the bottom of the Baltic sea, and the problems they encounter are also international.
     
Few have visited the bottom of the Baltic Sea, but the effects of human activity are evident there, and come back to punish those who live along the shore. In wide areas, the bottom, which has a low oxygen content by nature, is completely lifeless. And that is not all.
     "In wartime, about 150,000 mines were put in the Baltic Sea. About 35,000 of them have been cleared away, and the fate of the rest is unknown", says Ola Oskarsson, head of Marin Mätteknik, the Swedish company that operates the Pollux.
     The computer is restarted, and the Pollux continues its way slowly near the Danish island of Bornholm.
     Yevdokimov guides the remote-controlled submarine, which is operating at a depth of more than 100 metres. The sub has a very sensitive metal detector, which could find a key chain that was dropped into the sea.
     
Nord-Stream wants to lay two pipes over 1,200 kilometres in length along the sea bottom from Russia to Germany. The route must be cleared of any refrigerators, shopping carts, large boulders, and other similar objects - especially old mines.
     Yevdokimov guides the Comanche submarine from the control room on the mother ship. If the Comanche finds a large metal object, another submersible is used to investigate it further and take pictures. The bottom is mostly empty and desolate, and the work, which has lasted for months, is excruciatingly dull.
     The route of the planned pipeline is the most closely charted stretch of the Baltic Sea. Every rock, gully, and bump along a 15-kilometre-wide area of the 1,200-kilometre route is known, as well as every sunken ship and other object of human origin in the vicinity. The geology of the bottom is also known in fine detail.
     "The whole idea is to lay the pipeline along a route, where there would be no need to do anything to the bottom, and that there would be nothing in the way that would have to be avoided or cleared away", says Bob Pirie, a British supervisor working for Nord-Stream. Most of the bottom is free of obstacles. Only the Gulf of Finland is problematic, with a very uneven bottom and large amounts of human junk.
     
The depths east of Bornholm are avoided. In that area, the allies sank large quantities of German chemical munitions. Ola Oskarsson is not too worried about them. "I would imagine that it would be best to leave them there. I don't know of a good way to raise them, but perhaps I would not go fishing there."
     
Old weapons, cables, and pipelines are nevertheless a minor problem. A bigger one stems from the pollutants that people put in the water. Emissions of detergents and fertilisers add to the phosphorous at the sea bottom. If the oxygen runs out at the bottom, phosphate begins to dissolve into the water, which promotes the growth of toxic blue-green algae.


Previously in HS International Edition:
  Baltic Sea needs urgent attention (14.4.2008)
  Russian journalist: gas pipeline´s damaging environmental effects underestimated (15.4.2008)
  Baltic Sea gas pipeline project facing big difficulties (10.3.2008)
  Cost of Baltic Sea gas pipeline looks to be higher than expected (8.1.2008)
  St. Petersburg reduces phosphorous emissions into Gulf of Finland (2.10..2007)

Links:
  Nord Stream (Wikipedia)

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