Náttúrufræðingurinn - 1978, Qupperneq 63

0.3—126 j.ig l-1 ancl be signií'icantly lower
at Krafla than Námafjall, whereas the
mercury concentrations ranged from 40—
1782 ng l-1 and were generally higher at
the Krafla field. Large variations in the
mercury concentrations were found
among the Krafla drillholes where two
hydrothermal systems of different charac-
teristics have been proposed. Mercury was
chiefly found in drillholes wliich extend
into the lower gas-rich high temperature
(320—340° C) system. The data which is
however limited suggest a linear relation-
ship between mercury and carbon dioxide.
ln the second survey ot the Námafjall
drillholes, an increase in the mercury con-
centration was noted; this is thought to
be associated with volcanic events in
April 1977 which affected the drillholes
by increasing pressure and carbon dioxide
concentrations. Assuming that 10 drill-
holes will supply the Krafla geothermal
power plant with steam, the resultant
mercury emission rate will be about 8.8 x
10» g yr->, most of which is thought to
enter the atmosphere.
57