ISSN:
1432-0495
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Groundwaters from crystalline and metamorphic rocks (hardrocks) and from Quaternary deposits, i.e., alluvial and glacial deposits (softrocks) from the counties of Nord-Trøndelag and Sør-Trøndelag were analyzed for major and minor elements and ions including fluoride. The median concentration of F− in water from the hardrock aquifers is 0.28 mg/l (14.7 μeq/l) in contrast to water from softrock aquifers in which it is found to be 0.05 mg/1 (2.6 μeq/l). More importantly, ca. 15% of the locations where water was abstracted from hardrock wells contain 1.5 mg/l (78.9 μeq/l) F− or more. Thus, 15% of all hardrock wells returned F− results that are at or above the maximum recommended value for drinking water. Of the softrock wells, none are above 1 mg/l. Geologists would normally expect higher F−contents in groundwaters derived from acid rocks, e.g., in granitic or gneissic areas. When comparing the host lithology with the observed F−contents, however, no clear relationship between F− content and lithology is visible. The highest observed F− values actually occur in gneissic host rocks. However, wells drilled in amphibolites/greenstones, mica schists, calcareous rocks, and sedimentary rocks all returned some analytical results above 1.5 mg/l F−. These results suggest that all hardrock wells drilled should be tested for F− and the users informed about the results and advised to take any necessary precautions. When applying the recently proposed Norwegian drinking water limits to our data, 51% of all softrock well waters and 56% of all hardrock well waters are unfit for consumption without prior treatment, although we analyzed only for about half of the proposed elements/parameters. This result seriously questions the concept of fixed action levels—many of them with totally unproven health implications—for so many parameters/elements for hardrock groundwaters.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00768736
Permalink
