Jökull - 01.12.1987, Page 42

Fig. 6. The effect of partial degassing on C02-N2-tem-
peratures (A) and calculated steam condensation (B and
C). Adiabatic boiling was assumed and an initial N2
concentration of 0.71 mmoles/kg. The curves show how
the calculated values for tco N , Zb and Zc relate to N2
degassing of water initially at ^00°C, 250°C and 300°C.
— Áhrif hlutaafgösunar djúpvatns á C02-N2-hitastig (A)
og á reiknaða gufuþéttingu (B og C). Gert var ráð fyrir
innrænni suðu og að upphaflegur styrkur N2 í djúpvatn-
inu nœmi 0.71 mmól/kg. Ferlarnir sýna hvernig reiknuð
gildi á tco^N , Zb og Zc breytast með N2 afgösun á vatni
sem var upphaflega við 200°C, 250°C og 300°C.
much lower than those observed. Lack of steam samples
from the Krísuvík field giving strongly negative Z-values
is thus taken to indicate that the fumarole steam has
been derived from undegassed, or little degassed water.
Some 30% degassing with respect to N2 would explain
the lowest Z-value (sample 5 in Table 4). It should,
however, be pointed out that atmospheric contamina-
tion which increases the N2 content of the steam samples
will have the opposite effect of partial degassing. There-
fore, primary N2 degassing may truly be in excess of
30%.
The calculated amount of condensation, up to 50%,
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