Sjöars inverkan på metallackumulationen i havsvikar - En undersökning av metallmobilisering från sura sulfatjordar

Acid sulfate soils covers an area area about 600 km-2 along the coast line of Northern Sweden. These soils originate from land uplift and oxidized sulfide soils. The oxidation process releases sulfur and Fe(III) and will lower the pH-value and mobilize metals that will cause toxic environments for water living organisms. Concerns of how higher occurrence of extreme weather conditions will affect the mobilization of metals has occurred. Understanding of the mobilizations of metals in different catchment conditions is therefore important knowledge for preparation of risk analyzes to protect ecosystems from toxic effects. The aim of this study is to compare accumulation of metals in sediments from marine and limnic environments to investigate how lakes effects the mobilization of metals in catchments consisting of acid sulfate soil. Answering the questions of accumulation differences between the catchments and how organic matter affects the mobilization and accumulation of metals. Sediment cores were collected in two different catchment areas, known to be affected by acid sulfate soils, in Västerbotten county. 22 different elements were analyzed by x-ray fluorescence spectroscopy and Loss-on-ignition (LOI) was used as a proxy for organic matter. The results indicate that draining of land areas, often due to agriculture and deforestation, increases mobilization and accumulation of metals correlated with both organic and lithogenic fractions to a large extent. However, elements such as S, Ni, Zn, Fe, Cu, Na, Mg, Al, Rb, Sr and Zr are derived from mobilization from acid sulfate soils where elements with high correlation with organic matter accumulates in limnic environment conditions.