Jökull - 01.12.1990, Blaðsíða 111

Figure 5. Core no. 2, showing the core
coverage of the integrated sample 2.1,
the coverage of the downcore samples
2.1, 2.2, 2.3... etc., the locations of
ice lenses in the core and some down-
core chemical changes. The ice lenses
are shown by the hatched lines but the
length of each core step is shown by
the solid lines. The 1986-1987 precip-
itation layer is shaded. — Línuritfyrir
kjarna 2. Orin sýnir hvar heildarsýnið
2.0 (Tafla 1.) er tekið úr kjarnanum en
ferningarnir hvarsýnin íTöflu3 eru tek-
in úr kjarnanum. Þverlínur eru dregn-
ar í kjarnann við hvern borunaráfanga
en kjarni 2 var boraður í 11 áföngum.
Brotalínurnar sýna hvar íslinsur eru
í snjónum. Snjólagið frá 1986-1987
er skyggt. Hœgri hluti myndarinnar
sýnir hvernig sýrustig, styrkur klóriðs
og styrkur natríums breytist niður eftir
kjarnanum (Tafla 3).
core 1 and 2, shown by the unshaded part of the core
below 190 cm depth (Figs. 4 and 5), range from pH
^•4 to 5.55. This is slightly higher than the average
PH (5.4) of precipitation in Iceland (Fig. la) and still
about 0.2 pH units lower than the pH of pure water sat-
urated with air at 25 °C. This minuscule acidification
's probably caused by sulfuric acid, originating from
the buming of fossil fuel. If the 0.9 ppm chlorine
concentration in and close to Grímsvötn represents
the original concentration of the precipitation and this
chlorine is of marine origin, this concentration trans-
lates then to one drop of sea water versus 19000 drops
°f pure water originating from evaporation and the
condensation of water vapor.
The ratio of the major ions in the snow versus chlo-
rine is shown in Fig. 8. As shown in Fig. 1, all of the
major dissolved solids in Icelandic precipitation, ex-
cluding carbönate and perhaps sulfur and calcium, are
of marine origin, since their unfractionated ratios are
close to the marine ratios, represented by the lines in
Fig. 1. The same lines are shown in Fig. 8, except the
intercepts for Ca2+ andS042~ are not included. Most
of the snow samples shown in Fig. 8 have experienced
partial melting and therefore chemical fractionation.
If the original ratios in the precipitation for Na+/Cl_,
Mg2+/cr, K+/C1- is marine, similar to the one in
Fig. 1, the results in Fig. 8 suggest that during partial
melting Cl“ and Na+ are released at similar rates be-
JÖKULL, No. 40, 1990 107