Climate impact on contaminant dispersion in the river basin of Göta Älv, Sweden

This study is the result of the DiPol project (Impact of climate change on the quality of urban and coastal waters) that was conducted 2009-2012 as part of the EU Interreg IVB North Sea Program. The overall aim with DiPol was to gather knowledge regarding how climate changes affect water quality. Additionally, to communicate such knowledge and increase awareness about climate changes among decision makers to be able to counteract the effects of climate changes both on the local and regional levels as well as to involve the general public in this work. Four study sites were choosen in Sweden, Norway, Denmark and Germany. This report covers the results from the Swedish study site; the river basin of Göta Älv. Based on samples from wet and dry periods as well as spring flood events, this study presents a possible relation between a short term increase in precipitation and enhanced contaminant transport in urban water courses of the Göta Älv river basin in Sweden. Elevated metal and PAH concentrations (polycyclic aromatic hydrocarbons) in the studied river system was linked to increased surface runoffs and shallow groundwater flows from urban areas, rather than re-suspension of river sediments. Based on future prediction of precipitation, also the climate change impact on ground water levels and river discharge are shown together with other consequences such as contaminant transport in rivers of this region. This study demonstrates an enhanced contaminant transport from urban areas to the river system due to increased precipitation and ground water levels