Quality of the surface sediments of the northern coast of the Gulf of Finland, Baltic Sea

• Quality and toxicity of the coastal Gulf of Finland was assessed using sediment quality guidelines.
• Heavy metal and arsenic deposition in surface sediment of the coastal Gulf of Finland 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.
• There is a need of local sediment quality guidelines in the Baltic Sea.

The Gulf of Finland is a shallow sea where a multitude of activities compete of space. Many of the activities include reworking of the sea floor. The gulf is known to have been rather largely contaminated by heavy metals during the last century, and although indications of recovery have been reported, it is crucial to know the levels of sea floor sediment contamination before any decisions of activities are taken by the authorities. In order to predict sediment toxicity the sediment concentrations acquired during a study from 2001 to 2004 are compared to Canadian sediment quality guidelines (SQG: s), which reveal that in the majority of the subsamples the metals and arsenic exceed the threshold levels of the used SQG: s, some exceed also the probable effect level. As, Cd, Hg, and especially Zn concentrations occur at unacceptably high levels in the coastal Gulf of Finland sediments.