305 SEDIMENT GEOCHEMISTRY AND USE OF THE SEAFLOOR OF THE GULF OF FINLAND by Henry Vallius Vallius, H. 2011. Sediment geochemistry and use of the seafoor of the gulf of Finland. Geological Survey of Finland, Special Paper 49, 305–313, 7 fgures. The Gulf of Finland has during the second half of the last century been under such stress as never seen before. Human activity in its catchment has introduced large amounts of harmful substances and nutrients into the water column. These substances can still be found in the offshore modern soft sediments of the Gulf of Finland. At the same time, all marine activities, except fshing, have expanded many-fold. The shift from the command economy of Soviet times to the current open market economy in Russia has increased marine activities many-fold, but at the same time it has initiated a slow recovery of the seafoor. The condition of the seafoor during the last two decades has clearly improved from the worst times in the early 1980s, but it takes a long time for the submarine environment to fully recover. In particular, submarine works in connection with various types of new infrastruc- ture, such as pipelines, cables, wind parks and submarine mining, are a new threat for the shallow and sensitive Gulf of Finland. Keywords (GeoRef Thesaurus, AGI): environmental geology, marine pollution, marine sediments, geochemistry, heavy metals, human activity, Finland, Baltic Sea, Gulf of Finland Geological Survey of Finland, P.O. Box 96, FI-02151 Espoo, Finland E-mail: henry.vallius@gtk.f Geoscience for Society 125 th Anniversary Volume Edited by Keijo Nenonen and Pekka A. Nurmi Geological Survey of Finland, Special Paper 49, 305–313, 2011