Content of PhD-studies
Patterns and controls of fluorine in boreal surface and groundwaters
The focus of my research is the hydrochemistry of fluorine in boreal waters, which includes the interaction perspective between bedrock, soil, ground- and surface waters. Fluorine (in nature mainly referred to as the anionic form called fluoride, F-) is an excellent tracer of sources and reactions in aquatic systems due its special chemical characteristics. Aim of the research is to increase the understanding of the behavior of fluorine in waters at different levels in the ground (from the surface down to 1000 m or more) in the boreal environment.
The Äspö Hard Rock Laboratory (ÄHRL) and the Forsmark and Simpevarp Site Investigation areas are excellent sites for the study. In these areas, a wealth of background information on petrology, structural geology, quaternary geology, pedology, ecology, microbiology, hydrology, geochemistry and hydrochemistry exists, which means that the sites have world unique status with respect to scientific characterization and understanding. This leads to unique opportunities for in-depth studies of various kinds, including hydrogeochemical characterisation of fluorine.
Existing data of fluorine in waters (streams, lakes, groundwaters) and solid materials (soil, overburden, bedrock, mineral) from Simpevarp, Forsmark and the ÄHRL will be comprehensively reviewed and analysed by means of statistical methods. Samples will be collected in the surface waters (including streams and lakes), overburden groundwaters as well as in bedrock groundwaters in the ÄHRL, Forsmark and Simpevarp. The sampling will, as far as possible, be coordinated with the existing hydrochemical monitoring programmes at these sites.
A boreal stream with significantly elevated concentrations of fluoride, caused by the weathering of fluoride-rich minerals such as in Götemar granite (top left corner).
Overall, there will be an increase in the understanding of how fluorine is distributed, in which species it occurs, and which its main sources and sinks are in surface waters, near-surface ground waters and deep ground waters in crystalline (Proterozoic granitoidic) bedrock environments in boreal areas. This will allow us to construct a conceptual model of how this element react and move, both in temporal and spatial dimensions, in water bodies of such areas. This, in turn, will make it possible to also predict hydrological pathways and the reactivity and transport of fluorine within these systems. Such possibilities have important socioeconomic implications, not the least for the nuclear industry.
Since fluoride is of critical health concern in many regions of the world (e.g. eastern Africa and central Asia) the results of this research may be implicated to issues concerning drinking water quality and the understanding of the relationship between geochemistry and biota (i.e medical geology). In fact, more than 30% of the private wells in Sweden are considered as having undrinkable water due to high fluoride concentrations.
Supervisors
Main supervisor, Prof. Mats Åström
Co-supervisor, Dr. Pasi Peltola