Arsenic in groundwater in Finland

In Finland, arsenic and radon are the substances which cause the worst groundwater quality problems in individual private wells.

Occurrence of arsenic

Elevated arsenic concentrations are detected in some parts of Finland because of the mineralogical composition of the bedrock. Arsenic is a problem especially in drilled wells. According to the data-base of the Geological Survey of Finland, about 7% of the drilled wells have arsenic concentrations greater than 10 micrograms per litre (μg/l). Arsenic is not a problem, however, in public water-works. The highest arsenic concentrations in drilled wells are found in moraines with high levels of arsenic.

 Map 1 shows arsenic concentrations in moraines.

Removal of arsenic from groundwater

In a research project, the Finnish Environment Institute identified simple and easy methods and equipment for removing arsenic from private wells. Two recommended methods are reverse osmosis and filtration with activated alumina (aluminium oxide).

Research project on arsenic

The Geological Survey of Finland has started an extensive three-year research project on risk as-sessment and risk management of arsenic in the Tampere area (RAMAS (2004-2007). Arsenic and its compounds are on the list of the main contaminants found in the Tampere region.  The aim of the RAMAS project is to create a procedure for assessing and managing the risk of arsenic.