FATE OF MERCURY IN THE ARCTIC Michael Evan ... - COGCI

Fate of Mercury in the Arctic 67
pg/m 3
pg/m 3
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
Cold and warm heating Mantles, RGM measurements 2002
Cold heating mantle
Warm heating mantle
0.00
16-apr 17-apr 18-apr 19-apr 20-apr 21-apr 22-apr 23-apr 24-apr 25-apr
Time
Figure 9. Parallel measurements of RGM at Station Nord, Greenland. Warm denuders were +50 0 C cold
denuders were at ambient temperature, approximately -30 0 C each point represents the
averaged concentration of two denuders. Note: Results near 0.00 pg m -3 cover each other, for
cold and warm denuders.
In Figure 9., page 67, it is seen that the annular denuders heated to 50 0 C using the improved
heating caps, give higher RGM concentration values, when RGM concentrations are higher than
approximately 10 pg m -3 and when there is apparently little, 5 pg m -3 or no RGM, the heated or non-
heated denuders report the same amounts. Each point represents the average of parallel
measurements.
Controlling the heating of the denuders is not just important in the field, but as seen from Figure
10., page 68, also important during laboratory analysis. Landis et al., 2002 note the need for coaxial
fans and good insulation to limit the heat escaping from the clamshell denuder oven and warming
the teflon sampling lines connecting the denuder to the charcoal filter on the inlet side, and the
mercury monitor on the outlet side. Figure 10., page 68, is an experiment where a single denuder,