Figure 2. Color change in meltwater fractions 25 through 30.
Table 5 gives descriptive information, total plate
100 mL, except for the final sample and rinse-water
counts, and fecal streptococcal counts for each melt-
sample where the counts were only slightly higher, 24
CFU/100 mL. There does not appear to be any prefer-
water fraction. Again, the initial samples had signifi-
ential survival of bacteria based upon gram reaction or
cant color and odor while the final samples were rela-
cell wall composition, as approximately half (46% [11
tively clear and had minimal odor. In this case we did
of 24]) of the bacteria in the meltwater were gram posi-
not see the multiple concentration events that were ob-
tive (Table 5) and the remainder were gram negative.
served in the first study, especially with respect to color.
In the previous study, the concentration events were
Outdoor study
associated with a period of prolonged warmth that fol-
In this study, the snow column was placed outside,
lowed a significant freezing event. In this study, this
and all the fractions were collected and sampled. Table
occurred on August 4 and we observed that the first
6 gives information on the color and odor of these
samples drawn after this event (on 8/6) had more odor
samples. We see a similar concentration effect in that
than the previous samples.
Total counts were approximately 101 CFU/mL in the
the initial samples had significant color and odor.
initial meltwater and increased to 106 CFU/mL by the
Samples drawn on 7/23 show a slight concentration
event, corresponding with significant warming after a
end of the study when significant warming had oc-
freezing event. The final samples had some sediment
curred. Again, there was a significant increase in the
and thus were a little cloudy but had only a faint musty
number of bacteria in the meltwater when compared
odor. Total counts fluctuated from 101 CFU/mL to 103
with the initial concentration in the snow sample (Table
4). Fecal streptococcal counts were generally <2 CFU/
CFU/mL throughout the experiment and did not in-
Table 4. Summary of total numbers of bacteria in snow and meltwater-
calculated values.
Total vol.
Total number
Number of
Total number of
meltwater in
of bacteria in
bacteria in last
bacteria in all
columna
snow columnb
meltwater
meltwater
(CFUc)
fractiond (CFU)
fractionse (CFU)
Study #
(mL)
2.0 107
9.9 108
1
7360
--
1.9 107
6.7 108
2
7200
--
1.73 106
7.2 105
2.3 106
3
5760
aTotal
volume in column = (mL/bottle)(# bottles collected from column).
bTotal
number bacteria in snow = (# CFU/mL in snow)(total # mL melted snow in column).
cColony Forming Unit
dNumber bacteria in last meltwater sample = (# CFU/mL in sample)(# mL in sample).
eTotal number bacteria in all the meltwater = Σ #5 for all the fractions.
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