Jökull - 01.12.1963, Blaðsíða 17

cause of the fineness of the particles a usual
filter papers was in the majority of cases not
effective in removing all suspended matter. The
first two samples were however filtered in this
way and liigh values for dissolved solids in the
samples from Fúlilakur may be caused by sus-
pencled matter, which went through the filter
paper. For subsequent samples ultrafiltration
was applied using organic membrane filters
which effectively removed all suspended matter.
Silica and sulfate were determined gravimetri-
cally. Calcium and magnesium were titrated to-
gether with EDTA using eriochrome bfack as
indicator. Caicium was then titrated in a sepa-
rate aliquote with murexide as indicator and
magnesium obtained as difference. An EEL Tit-
rator was used for these determinations. Sodium
and potassium were determined fiamephoto-
metricaliy with a Beckman DU instrument with
the oxygen-acetylen atomizer burner. In these
dilute waters correction for flame background
is unnecessary and the concentrations were de-
termined against standard prepared from the
pure chlorides of sodium and potassium. Chlo-
ride was titrated according to Mohr’s method.
A separate sample for the determination of
hydrogen sulfide was obtainecl and zinc-acetate-
solution added in the field. Sulfide was then
determined colorimetrically with paraaminodi-
methylanilin and ferric cforide. Fluoride was
determined using the zirconium-alizarin method.
(U.S.G.S. Water Suppfy Paper 1454).
The analysis oí all three rivers (Tables 2, 3, 4)
shows a general tendency towards lower amounts
of dissolved solids during the summer months
as would be expected by greater dilution during
rnore rapid melting of the glacier. Measurements
of discharge in the rivers Múlakvisl and Fúli-
leekur are difficult because of the braided char-
acter of the river beds. Skálm on the other hand,
is confined to a stable becl and discharge
measurements can be made more easily. Ap-
proximate discharge of Skálm and calculated
arnount of total dissolved load is shown in
Table 5. In Fig. 3 is shown the change in dis-
solved solids with time for the three rivers. The
variation is greatest in Fúlilœkur and Múla-
kvísl but less pronounced in Skálm. Assuming
similar relative changes in the discharge of
Fúlilcekur and Múlakvísl a distinct minimum
in the total dissolved load of Fúlilcekur occurrs
during the summer months, whereas in Múla-
kvísl and Skálm the total dissolved load is con-
stant or even at a maximum in the fatter during
the varm period. These differences are affected
TABLE 2
Analysis of water from Fúlilcekur (Jökulsá á Sólheimasandi).
15-1- ’63 10-3-’63 22-4-'G3 4-6-’63 3-7-’63 9-8-’63 l-10-’63 3-11- '63 14-12-’63
ppm epm ppm epm ppm ?pm ppm epm ppm epm ppm epm ppm epm ppm epm PPm epm
Si09 18.4 9.6 10.8 9.2 10.0 6.4 17.2 13.2 19.6
Ca 11.2 0.56 6.9 0.34 7.4 0.37 8.4 0.42 5.2 0.26 6.1 0.30 7.7 0.38 10.2 0.51 11.4 0.57
Mg 3.4 0.26 1.8 0.15 1.9 0.15 1.5 0.12 1.6 0.13 1.5 0.12 2.3 0.19 3.4 0.28 2.7 0.22
Na 12.0 0.52 10.0 0.44 n.d. 6.2 0.27 5.7 0.25 0.7 0.29 15.5 0.67 17.5 0.76 16.0 0.70
K 1.7 0.04 1.5 0.04 n.d. 1.3 0.03 1.2 0.03 0.4 0.01 1.5 0.04 1.0 0.03 1.6 0.04
1.40 0.97 0.84 0.67 0.72 1.28 1.58 1.53
C1 8.2 0.23 6.5 0.18 5.0 0.14 5.2 0.15 4.2 0.12 4.2 0.12 6.5 0.18 16.4 0.46 9.7 0.27
so4 12.0 0.25 6.1 0.13 5.9 0.12 5.3 0.11 4.3 0.09 5.6 0.12 8.6 0.18 9.5 0.20 9.9 0.21
F 0.3 0.02 0.1 0.01 0.05 0.03 0.15 0.08 0.1 0.01 0.1 0.01 0.25 0.01 0.15 0.01 0.25 0.01
HC.Os 74.4 1.22 43.3 0.71 45.1 0.74 44.5 0.73 37.8 0.62 37.8 0.62 62.8 1.03 62.8 1.03 76.3 1.25
1.72 1.03 1.03 1.07 0.84 0.87 1.40 1.70 1.74
Dissolved
solids 168.0 132.0 97.2 62.8 42.4 50.4 90.8 99.2 113.2
H0S 0.1 n.d. 1.0 n.d. 1.2 n.d. n.d. n.d. n.d.
pH 6.84 7.10 7.25 7.30 7.00 7.08 7.05 6.80 6.70
JÖKULL 1963