The investigation of the sediments in the lake Hörntrasket was part of the project aimed to find the reason for the reduction of the lake fauna. Earlier investigations have showed elevated concentrations of some of the metals in the lake water.

One of the goals of our part of the project was to explain reasons for high metal content in the lake water. We had three hyphotesis: pollution from the mining industry, release from natural sources such as bedrocks and release from the lake sediments. The profile of bioavailable concentrations of the 12 heavy metals in the sediment pore water were determined using in situ sediment probe deployed in the spring season in the four sites in lake. The bioavailable metal pollution in lake sediment, situated in mining area, was relatively low.