Inverkan av dikning av sulfidjordar på metallkoncentrationer i havssediment : En studie av hur metallhalten i havssediment i Gumbodafjärden (Norra Sverige) har förändrats över tid

Sammanfattning: Acid sulphate soils cover all around the world an area of approximately 170 000 km2. The soils can cause huge acidification problems for streams and lakes due to increasing concentration of hydrogen ions which will increasing the mobilization of heavy metals. This can result in huge complications for species living in the polluted water. The aim with this study was to see what kind of impact the ditching activity in a catchment area affected by sulfide soils have when it comes to the leaching of heavy metals and Al. This was studied by investigate the distribution of 27 different elements (such as heavy metals, trace metals, nutrient etc) and LOI in a 2,14 m long marine sediment core from a bay situated in the county of Västerbotten. The catchment area from the stream which has it outflow at the bay are predicted to be affected by the acid sulphate soils in a high extent. Furthermore the spatial distribution of the elements in the bay was studied, this was made by compare the results from two sediments samples taken by a HTH corer from two different locations. The results made it clear that some element highly correlated to each other followed a trend similar to the ones of Sulphur and LOI. The concentration for the elements (As, Cu, Fe, Mn, Ni, Pb och Zn) was also compared by the Canadian guidelines which indicate that As and Fe had concentration that can cause severe negative effects for biota in the water. The conclusion made from this study indicate that the majority of the elements are affected by the LOI fluctuations due to the high positive or negative correlation to LOI. Therefore the highest concentration of elements such as Al, Co, Cu Mn, Ni and Zn which will be leached by acid sulphate soils are in this situation instead caused by LOI. However there occur some trends when the ratio between S/LOI and other heavy metals sharply  increase, this could be seen as a sign of an effect caused by acid sulphate as a results of ditching activity.