Stockholm university

Reversing Eutrophication with Activated Limestone – Can we help the Baltic Sea?

Eutrophication is the gradual increase of nutrients such as phosphorus (P) and nitrogen (N) in lakes and seas. While N can re-enter the ecosystem via the natural nitrogen cycle, there is no natural remedy for P, and unless physically removed, P stays in the aquatic environment forever. Therefore, the removal of P from eutrophicated systems is of utmost importance.

The Baltic Sea is suffering from severe eutrophication, leading to the growth of plant life such as algae – causing the dreaded algal bloom and depleting oxygen content in the sea floor, killing other marine life. Even though the Baltic countries have recently implemented stricter measures to control P flux into the Baltic Sea, P levels are still significant in the sea bed, which makes eutrophication active during annual water circulation. 

Researchers from a Swedish company (Levande Hav AB, Swedish only)) and the Department of Materials and Environmental Chemistry (MMK) at Stockholm University, in partnership with other Swedish companies, have developed a new material called activated limestone. This promising sorbent can fix P in the sediment and thus reduce algae growth in water.

The researchers have developed and spread 30 tons of activated limestone in the study bay Kyrkviken Gryt, about 230 km south of Stockholm. County Administrative Board, Östergötland, Sweden, independently monitored the P-level and other water quality parameters. 
Results from lab experiments and field studies indicate that the activated limestone can bind P at the sediment level, making this a promising material to rejuvenate the Baltic Sea.