[ Introduction ]
[ State ]
[ Pressure ]
[ Response ]
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The yearly trends in phosphorus and nitrogen concentrations in the Gulf of Riga reflect eutrophication process in this productive region of the Baltic Sea. Nitrogen concentrations were increasing during the 1970ies and 1980ies, but in recent years, they have decreased significantly. The phosphorus concentrations increased also during the 1990ies.
Data on nutrient discharge from runoff do not explain the rapid fall of nitrate amounts in the Gulf during the 1990ies and the further accumulation of phosphorus. Release of phosphates from bottom sediments and the losses of available nitrogen in denitrification process may have hastened the reduction of nitrogen concentrations and caused the accumulation of phosphorus during the 1990ies, when nutrient discharge from rivers was low.
Sources: Institute of Aquatic Ecology, University of Latvia
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The Concentration of Oil Hydrocarbons in the Gulf of Riga
The mean concentrations of oil hydrocarbons between May and September 1997 were 13.4 mkg/l along the coast of the Central Baltic, 6.3 mkg/l in the open part and 7.8 mkg/l near the coast of the Gulf of Riga. Along the Baltic Coast, Northern part have been the most polluted with the maximum value of 21.9 mkg/l. In the Gulf of Riga three areas of increased pollution were detected with a maximum oil hydrocarbon concentration of 33.5 mkg/l.
Microbiological Quality of the Coastal Bathing Water
The most important indicators of microbiological quality of bathing water are the total number of coliform bacteria and the number of faecal coliforms (Escherichia coli) in water.
In 1997, a reduction of the bacteriological levels was observed in the coastal bathing water. 94% of samples analyzed were in compliance with the mandatory requirements for the quality of bathing water. A microbiological quality harmful for bather health was detected in 6% of cases.
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