Enrichment of trace metals from acid sulfate soils in sediments of the Kvarken Archipelago, eastern Gulf of Bothnia, Baltic Sea

Trace metals from acid sulfate soils, delivered by rivers in western Finland, have been found to significantly enrich sediments in the Kvarken Archipelago of the Baltic Sea. This enrichment, particularly noticeable since the 1960s due to artificial drainage, extends at least 25 km seaward and is likely causing detrimental effects on marine biota more than 12 km from river mouths. The study identifies a key mechanism for metal transport: the transformation of dissolved organic matter and metals into metal-organic aggregates, alongside co-precipitation with manganese oxyhydroxides. Additionally, terrestrial organic carbon constitutes a substantial portion (39–48%) of total organic carbon in these sediments, underscoring the importance of riverine organic matter supply. These findings are critical for assessing environmental risks and managing sensitive coastal ecosystems.

Virtasalo, J. J., Österholm, P., Kotilainen, A. T., & Åström, M. E. (2020). Enrichment of trace metals from acid sulfate soils in sediments of the Kvarken Archipelago, eastern Gulf of Bothnia, Baltic Sea. Biogeosciences, 17(23), 6097–6113. https://doi.org/10.5194/bg-17-6097-2020