1. 1Thule Institute, Center of Northern Environmental Technology (NorTech Oulu), University of Oulu, FI-90014 P.O. Box 7300, Oulu, Finland
2. 2Faculty of Technology, Environmental and Chemical Engineering Research Group, University of Oulu, FI-90014 P.O. Box 4300, Oulu, Finland
3. 3North Ostrobothnia Center for Economic Development, Transport and the Environment, Environmental Protection Unit, FI-90101 Oulu, P.O.Box 86