Natural factors influencing strontium concentrations in bulk and throughfall deposition, soil solution and litterfall in forest ecosystems on Olkiluoto Island, southwestern Finland

We studied the total concentrations of naturally occurring Sr in bulk deposition, stand throughfall, soil solution and litterfall in forest ecosystems located on Olkiluoto Island in southwestern Finland; in order to estimate the importance of sea water, soil chemical processes and plant and soil interactions on the Sr cycling in coastal areas of Baltic Sea. The area is specific because of the brackish sea water and land uplift from the sea. Bulk deposition samples were collected from two plots located in open areas and the other samples from four forest stands typical on Olkiluoto Island. The variation in the Sr concentrations in the stand throughfall and soil solution followed closely the variation in the base cations and anions. The highest individual Sr, base cation and anion concentrations were determined in the black alder-dominated forest stand close to the shore line of the Baltic Sea due to sea, high weathering input and nitrification. Nitrification on this plot led to nitrate leaching and increased buffering of acidity and weathering. All these processes promoted the presence of Sr in soil solution. Increased concentrations of naturally occurring Sr were reflected similarly in all sampled media, i.e., in stand throughfall, soil solution and litterfall.