August 28, 2018

Removal of top-layer sediment

Removal of active top layer of sediment – Southwest Finland ELY Centre

Janne Suomela taking samples.

Two pilots on removal of organic, oxygen consuming, active top layer of bottom sediment will be carried out at two pilot sites in Finland. Potential methods for sediment removal will be tested and, based on the results, the effect and efficiency of these methods will be evaluated. The main objective of the measure is to eliminate the organic oxygen consumption processes in the sediment and, consequently, decrease the leakage of phosphorus from anoxic sediment to the water phase. Therefore, to gain information on the efficiency of the measure, the nutrient contents in the sediment will be measured and changes in nutrient concentration in the water above the sediment will be monitored thoroughly. The suitability and potential of the measure in Baltic Sea protection will be evaluated, especially for coastal anoxic bottom areas that have been historically under high nutrient load, with little possibilities of significant flora or fauna to survive without restoration measures.


Results from this pilot were presented in the SEABASED Final Webinar on January 26th, 2021. See the presentation behind this link. Read the final report of this pilot behind this link and the study on the incubation of the sediment behind this link (the study is in Finnish).

Anoxic sediment (gyttja clay) from Archipelago Sea.

Well oxygenated sediment surface.

For more information, please contact

Pekka Paavilainen, Senior Officer

Janne Suomela, Chief Specialist

Varsinais-Suomen ELY-keskus (Centre for Economic Development, Transport and the Environment for Southwest Finland)