Hydrogeology and groundwater quality in the Nordic and Baltic countries

Abstract

Groundwater utilization and groundwater quality vary in the Baltic and Nordic countries mainly because of different geological settings. Based on the geology, the countries were treated in the following three groups: (1) Fennoscandian countries (Finland, Sweden, and Norway), (2) Denmark and Baltic countries (Estonia, Latvia, and Lithuania), and (3) Iceland. Most of the utilized groundwater resources are taken from Quaternary deposits, but Denmark and the Baltic countries have in addition, important resources in Phanerozoic rocks. The groundwater quality reflects the residence time of water in the subsurface and the chemical composition of the geological formations. Concentrations of ions in the Fennoscandian bedrock are elevated compared to Iceland, but lower than in Denmark and the Baltic countries. Compared to groundwater in the bedrock, groundwater in Quaternary deposits has usually lower concentrations of dissolved minerals. Unconfined Quaternary aquifers are vulnerable to contamination. Examples from Denmark and the Baltic countries illustrate challenges and successful effects of mitigation strategies for such aquifers related to agricultural application and management of nitrogen. Confined and deeper groundwater is better protected against anthropogenic contamination, but water quality may be affected by harmful compounds caused by geogenic processes (viz, sulfide, arsenic, fluoride, and radon). HIGHLIGHTS The paper reviews groundwater quality, and groundwater utilization in the Baltic and Nordic countries.; Chemical data from all involved countries have been compiled and the data is summarized in the Supplementary Material.; The mineral composition of the underlying bedrock governs to a large extent the chemical character of groundwater in the Quaternary deposits.; Denmark and the Baltic countries have large and complex aquifers, whereas the aquifers in Iceland and the Fennoscandian countries are relatively small and with less complexity.; The groundwater in the region is largely of high quality, but local challenges exist related to geogenic (viz radon, arsenic, fluoride) and anthropogenic origin (viz nitrate, pesticides).;

Keywords

• baltic and nordic countries
• geological framework
• groundwater quality
• groundwater pollution
• groundwater utilization