Eutrophication and Phosphorous accumulation in sediments of Karlskärsviken, bay in Lake Mälaren

G. Olli (1)

1 Department of Physical Geography and Quaternary Geology

Biogenic silica (BSi) and phosphorous (P) accumulation were investigated in sediment cores from Karlskärsviken, a bay of Lake Mälaren. The aim was to understand and quantify environmental changes since the Middle Ages, with focus on industrial times, and to evaluate anthropogenic influences on the bay's water quality. The BSi accumulation in the sediments is a better indicator of former nutrient trophy than P accumulation and for this reason a BSi inferred P content, BSi-P, is calculated. There is an increasing trend of BSi-P content in the bay since the Middle Ages, with a small decrease in the inner bay section during the last decades. In Karlskärsviken, the shallow inner section of the bay, where the water quality is dominated by loading from the bay catchment area, is less nutritious than the water in the outer section, which is influenced by the main streams in the Lake Mälaren. The P content in the water column is presently higher than in the mid nineteenth century, and the P loading to Karlskärsviken is not found to have changed since the 1960s and 1970s.

Domaines: Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

G. Olli. Eutrophication and Phosphorous accumulation in sediments of Karlskärsviken, bay in Lake Mälaren. Hydrology and Earth System Sciences Discussions, 2007, 4 (3), pp.1823-1843. ⟨hal-00298850⟩