Jökull - 01.12.1990, Side 107

Table I. Chemical composition of snow cores. Integrated samples — Efnasamsetning safnsýna úr ískjömum
1-9.
Samplea Date6 d/m Location Lambert coordin. Ele- vation m.a.sl. Depth cm pH/r pH/°C Na ppm K ppm Ca PPra Mg ppm C1 ppm S04 ppm hco3 ppm
88-1.1 6/6 465676-433392 1680 0-252 5.67/22.7 0.509 0.045 0.019 0.051 0.91 0.386 0.140
88-1.2 6/6 465676-433392 1680 252-433 5.91/22.7 0.066 0.019 0.005 0.007 0.13 0.042 0.250
88-2.2 7/6 467925-434996 1427 0-532 5.75/22.7 0.367 0.024 0.019 0.034 0.78 0.221 0.170
88-3.l 8/6 471333-430639 1685 0-222 5.63/21.5 0.292 0.019 0.026 0.035 0.53 0.301 0.130
88-3.2 8/6 471333-430639 1685 222-458 5.45/21.7 0.370 0.024 0.024 0.047 0.69 0.358 0.090
88-4.1 8/6 473739-430678 1580 0-385 5.50/22.5 0.368 0.020 0.041 0.048 0.70 0.233 0.100
88-5.1 8/6 478614-430399 1495 0-347 5.50/22.1 0.323 0.015 0.026 0.036 0.77 0.361 0.100
88-6.1 10/6 484697-428800 1395 0-343 5.55/21.5 0.270 0.015 0.010 0.020 0.43 0.080 0.110
88-7.1 10/6 489853-427440 1300 0-333 5.47/22.0 0.347 0.017 0.040 0.034 0.58 0.211 0.090
88-8.1 10/6 496077-426106 1190 0-205 5.66/22.0 0.256 0.005 0.017 0.011 0.40 0.040 0.140
88-9.1 10/6 499365-425620 1120 0-144 5.73/21.7 0.175 0.010 0.017 0.010 0.29 0.072 0.160
”88-1.1“ 5.57 0.442 0.055 0.085 0.054 0.78 0.402 0.130
"88-2.1“- 5.59 0.499 0.027 0.043 0.048 0.91 0.313 0.130
”88-3.0“ 5.52 0.331 0.022 0.025 0.041 0.61 0.330 0.110
°the concentration of fluorine was below the detection limit of the
88-3.1 and 88-7.1 was 0.024,0.007 and 0.017 ppm respectively.
6all samples were collected 1988
constants of Plummer and Busenberg (1982). The
concentrations of H+ and bicarbonate are important
for the charge balance at relatively high and low pH
yalues. N03- and NH4+ were not analysed. Their
concentrations are low compared to the sea-salts in
the data base from the Icelandic Meteorological Office
(1957-1981).
Results and interpretations
The analytical results shown in Table I are for
integrated core samples. Sample 88-1.1 represents
the average of the integrated 1987-1988 precipitation
layer in core 1 but 88-1.2 the average of the integrated
1986-1987 precipitation layer in core 1. Sample ”88-
1-1“ is the calculated average of the individual 25 cm
samples of the 1987-1988 precipitation layer in core 1
(Table II). Sample ”88- 2.1“ is the calculated average
°f the individual ”25 cm samples" of the 1987-1988
Precipitation layer in core 2 (Table III) but the sample
88-2.2 represents the 1986-1987 and the 1987-1988
Precipitation layers in core 2. Sample ”88-3.0“ rep-
resents the 1987-1988 precipitation layers in core 3.
analytical method (0.02). The silica concentration in samples 88-1.1,
It is the weighted average according to sample length,
of samples 88- 3.1 and 88-3.2 in Table I. Tables II
and III show the results for downcore samples cov-
eringthe 1986-1987 andthe 1987-1988 precipitation
layers in core 1 and 2. The results are tested using
the charge balance equations 1 and 2. If all the major
ions are analysed, and the analyses are ”perfect“ the
charge balance should be zero. Samples tested with
equation 1, have a mean charge balance of -2.7% and a
standard deviation of 30% (Fig. 7a) but samples tested
with equation 2 have a mean charge balance of -8.8%
and a standard deviation of 20% (Fig. 7b). When the
pH is relatively high the bicarbonate contribution to
the charge balance becomes important, and when it is
included the greatest excess positive charge balances
are shifted towards zero as shown in Figs. 7a and 7b.
The four analyses resulting in charge balances below
-30% (sample 2.2, -39%, sample 2.3, -75%, sample
2.20, -47%, sample 1.2, -46%, Figs. 7a and b, Tables
I and III) should be treated with caution. N03_ and
NH4+ are probably not major ions in general but they
might be in some of the more dilute samples.
Spatial changes in the average chemistry of the
JÖKULL, No. 40, 1990 103