Bottom of Gulf of Finland remains in poor condition

Winter storms bring brief increase in oxygen

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The Gulf of Finland is still in poor condition, and the deepest parts of the narrow body of water are mostly without life.
      Last winter’s storms brought some oxygenated water to the depths. However, the benefits were short-lived, and by the summer, the oxygen had been depleted in many parts.
      A lack of oxygen on the bottom accelerates a process in which substances that increase eutrophication are released from the bottom to higher layers.
      The marine research vessels Muikku and Aranda returned from their sample-taking voyages in the Gulf of Finland and other parts of the Baltic. As was the case in previous years, the trips yielded worrisome information about the condition of the sea.
     
In the areas investigated by Muikku, only one third had oxygen in the bottom silt. Fauna on the bottom was scarce in wide areas, and in some places it was completely missing. In the oxygen-free depths, bacteria were the only forms of life that could be detected.
      Although the storms of last winter had improved the oxygen situation from a year ago, it was not enough to revive the sea bottom.
      According to Pentti Kangas, special researcher at the Finnish Environment institute, the stratified nature of the Gulf of Finland means that the different layers do not mix much, which helps maintain the poor oxygen situation at the lower levels.
      The oxygen reserves of the bottom layers are so small, that occasional boost from oxygenated water brought by storms does not last long.
      "Nature itself makes the situation difficult", Kangas notes.
      Little change has been noted in recent years. "The state of the Gulf of Finland is really poor. Bottom animals are missing almost everywhere", Kangas observes.
     
The studies by Aranda indicate that the oxygen situation in deeper water in the Gulf of Finland weakened considerably during the summer, and that in two locations, toxic hydrogen sulphide was detected.
      The oxygen situation of the main basin of the Baltic Sea is very poor. Juha Flinkman, special researcher at the Finnish Institute of Marine Research, says that large amounts of phosphates have been released from the depths, which was reflected in increased appearances of toxic blue-green algae in the area.
      In the main basin of the Baltic, nearly all water deeper than 70 metres was without oxygen. The situation is expected to have a detrimental effect on fish populations.
     
The phosphorous content of the Gulf of Finland has doubled since the early 1990s, as has the amount of algae that grows in the summer. Researchers say that the only way to improve the state of the sea would be a sharp reduction in pollutants coming from land.
     
Some improvement may be in store when the new sewage treatment plant in St. Petersburg, at the far eastern end of the Gulf of Finland begins operations.
      However, the plant will reduce the amount of waste water flowing from St. Petersburg to the Gulf of Finland by only 12 - 13%. About one fifth of the sewage of the large city will continue to be dumped untreated into the Gulf of Finland, mainly affecting areas in the open sea.
      The poor condition of Finnish coastal waters is largely caused by emissions originating in Finland.


Previously in HS International Edition:
  Weekend winter storm may improve water quality in Gulf of Finland (12.1.2005)
  Gulf of Finland still in bad shape (23.8.2004)
  Experts fear bad blue-green algae situation in Gulf of Finland this summer (10.5.2004)
  Heavy summer blue-green algae growth expected in Gulf of Finland (6.5.2005)

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