SLU news

Acidified or just acid?

Published: 22 February 2021
Lake with mountains in the background and two rowing boats in the foreground. Photo.

The Nordic countries assess the acidification of lakes and watercourses very differently. Researchers of SLU have together with Norwegian and Finnish colleagues suggested a new harmonized assessment system.

Sweden, Norway and Finland have developed completely different systems for assessing acidification. A new report finds that when these systems are compared on a common dataset, are major differences found. The authors of the report present a proposal for a harmonized Nordic classification system. 

The report is a collaboration between SLU and IVL in Sweden, NIVA, NORCE and NINA in Norway and YMPARISTO in Finland. The work has been led by Jens Fölster from the Department of Aquatic Sciences and Assessment. Kerstin Holmgren from the Department of Aquatic Resources has also participated in the project.  

The report is based on results from several projects financed by the Swedish Agency for Marine and Water Management and the Norwegian Environment Agency. 


Fölster J., Garmo Ø.A., Carlson P., Johnson R., Velle G., Austnes K., Hallstan S., Holmgren K., Schartau A.K., Moldan F., Aroviita J. (2021). Acidified or not? : a comparison of Nordic systems for classification of physicochemical acidification status and suggestions towards a harmonised system. Institutionen för vatten och miljö, Sveriges lantbruksuniversitet, Uppsala, Sweden, Rapport 2021:1