Applying sediment quality guidelines on soft sediments of the Gulf of Finland, Baltic Sea

• Sediment quality guidelines were applied for prediction of sediment toxicity in the Gulf of Finland.
• The use of two different sediment quality guidelines was evaluated in the case of the Gulf of Finland.
• Heavy metal and arsenic deposition in surface sediment of the eastern Baltic Sea is declining.
• As, Cd, Hg, and Zn concentrations still occur at unacceptably high levels.
• Zn is according to SQG:s predicted as the most toxic element in the sediments of the Gulf of Finland.

The Gulf of Finland is known to have been rather largely contaminated by heavy metals during the last half of the 20th century, but indications of recovery have been reported. In order to investigate the recent levels of heavy metals and arsenic in the uppermost soft sediments of the off-shore Gulf of Finland coring of altogether 23 sites were performed. The subsamples of the cores are 605 in total and thus give a good picture of heavy metal levels in the surface sediments during the first decade of this century. In order to evaluate methods and predict sediment toxicity the sediment concentrations are compared to American SQG:s. Majority of the subsamples exceeded the threshold levels of both used SQG:s, but some exceeded also the midrange effects quality guidelines. As, Cd, Hg, and Zn concentrations still occur at unacceptably high levels in sediments of the off-shore Gulf of Finland.