Rit (Vísindafélag Íslendinga) - 01.06.1976, Page 18

In most of the hot spring samples the deuterium and oxygen-18
concentrations are found to have a linear relationship characteristic
of meteoric water derived from the ocean through evaporation and
condensation processes. This supported the view that geothermal
water in Iceland is meteoric in origin. At the same time the results
showed that some hot springs could not originate from local ground-
water but must have their recharge area at a considerable distance.
In case of the Reykjavík geothermal area the hot water seemed to
have flowed into the area from the north-east, indicating flow along
the tectonic lines in the region rather than across them (Böðvars-
son 1962).
During his visit to Iceland in 1957, I. Friedman from the U.S.
Geological Survey collected 20 samples of hot and cold water from
different parts of Iceland. The sampling was continued by the
Physical Laboratory of the University of Iceland and, in 1961, 159
samples of geothermal water, cold subsurface and surface water
and monthly precipitation from one meteorological station in South-
west-Iceland were analysed for deuterium in Friedman’s laboratory
(Friedman, et al. 1963).
The measurements of surface water and precipitation gave an
idea of the distribution of deuterium content in precipitation
throughout the country. The highest concentrations of deuterium
in surface water were found on the coast and the lowest in central
parts of the country. On the north coast, surface water was found
to have a somewhat lower deuterium concentration than on the
south coast.
The decreasing deuterium content of the rain from the coast in-
land can be accounted for as a result of isotopic fractionation caused
by evaporation and condensation processes. These processes, which
are discussed in detail by Friedman et al. (1964) for deuterium and
by Epstein (1956) and Dansgaard (1964) for oxygen-18, will be
given special attention later in this work.
The higher deuterium content of the precipitation on the south
coast compared with the north coast is also understandable when it
is considered that the precipitation in South Iceland is mainly
caused hy southerly winds, which bring moisture from the rela-
tively warm sea south and southwest of Iceland, whereas precipita-
tion in North Iceland is mainly caused by northerly winds, which
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