Relation between Contemporary Water Chemistry and Historical pH from Paleolimnology to Estimate Reference Conditions in Swedish Lakes : Development of a simple tool for acidification assessment

Abstract: Acidification was categorized as the main environmental problem in Scandinavia during the 1960’s. Fortunately for Sweden, as with other countries in Scandinavia, has shown a process of recovery from acidification, by emission control. Further Sweden has had an extended liming program to mitigate the effects from acidification. Regarding the acidification assessment of the EU Water Framework Directive, it requires that EU members attain a ‘good ecological status’ in their surface waters. The status is defined as a deviation from a reference value and this is achieved using a reference reflecting a preindustrial state. As the waters are recovering from acidification the liming program can be reduced. Hence, there is a need to develop tools that can be used for decisions to stop liming in single waters. This study states three approaches: the well known hydrochemical model MAGIC, a meta-MAGIC model which calibrates the reference value computed by MAGIC model and paleolimnology studies. The latter is the key because it is the one that measures the reference value by immediate samples insitu. However, all methods have advantages and disadvantages, which allowed the development of an additional tool called meta-paleo for the same purpose. This meta-paleo model is designed based on an 11 years mean of contemporary water chemistry and paleolimnology data of 71 lakes. This tool for acidification assessment enables to work with few parameters of water chemistry. However it is concluded that the model has uncertainties, which should be evaluated so it can be used as a tool for decision making