Preserving the Balticenvironment

摘要

THE Baltic Sea is today a major resource for recreation for a population of over 85 million people in Northern Europe. It is naturally beautiful and is a home for a great number of different sea plants and animals. It is also the destination for hundreds, if not thousands, of treated and untreated sewage discharges and outlets. The sea has a history of being both sweet and salty in turns. Today it is a brackish water with an average depth of just 55 m, the deepest point being only 450 m, which compares to the average 1,000 m depth of the Mediterranean. The Baltic is special. Over the past decade several 'hot spots' have been identified as sources responsible for a major part of the pollution in the Baltic Sea. Many of these have had their harmful discharges reduced to a minimum - thanks to significant international cooperation. But still, the sea is continuously heavily exposed to pollution. So how well is the current urban water supply and sewerage infrastructure coping, given the systems receive sewage 24 hours a day from 85 million people, and how is this affecting the Baltic Sea? What is the overall structural and functional condition of these underground assets? How are they surveyed, maintained and rehabilitated? As an example this article looks at how these questions are answered in Helsinki, one of the region's capital cities enjoying the Baltic seascape.