HELCOM Baltic Sea Environment Fact Sheet 2019, published: 22.11.2019
The total amount of material deposited at Baltic Sea area is highly variable between years, depending widely on the occurrence of larger capital dredging operations. Total amount of material deposited in 2017 was around 9 million tonnes which is 2 million tonnes more than in 2016. This is mainly due to increase in capital dredging operations, as there were 1,5 million tonnes less maintenance dredging than in 2016. Dredged material was deposited at 108 depositing sites.
In 2017 the amount of material deposited at sea originated from capital dredging slightly prevailed over the maintenance operations. Capital dredging produced 4.9 million tonnes of the deposited material, which constitutes 55% of all dredged material deposited at sea in 2017. This amount slightly exceeds the volume produced by capital dredging in 2016 but remains much lower than the amounts reported in 2013-15. Most of the capital dredging in 2017 was reported by Russia and Finland.
Maintenance dredging in 2017 contributed slightly less than 4 million tonnes, which constitutes about 45% of all dredged material deposited at the Baltic Sea. This amount is slightly less than what was reported two previous years but a bit higher than 2013-14. The main contributors in 2017 were Russia, Latvia and Denmark.
59% (5.2 million tonnes) of the material deposited at sea in 2017 originates from sea, 27 % (2.4 million tonnes) from harbours or river estuaries and about 14% was reported as of unknown origin.
There were six major contaminants reported by countries in 2017: four heavy metals (mercury, lead, cadmium and copper), tributyltin and polyaromatic hydrocarbons. The proportion of TBT and PAHs in sediments from harbours/rivers is about 99% and 89% of total amount respectively. Most of the copper and mercury in dredged material originates from operations at sea (64% and 63%) while lead and cadmium are mainly from harbour/river sediments (64% and 55%).