Environmental Engineering Reference
In-Depth Information
change on the partitioning of glyoxal and methylglyoxal with photochemical age
(1-NO/NOx) in the chamber and in the atmosphere respectively. The effect seen is
that under high relative humidity (RH), the compounds will evaporate from the
particle phase more slowly than under low RH as photochemical age increases.
0
y
= -244.1
x
+ 238.2
R
2
= 0.665
Glyoxal
Methylglyoxal
-1
y
= -151.6
x
+ 145.9
R
2
= 0.850
Dry
Wet
-2
-3
-4
y
= -28.73
x
+ 25.28
R
2
= 0.304
y = -41.58x + 36.62
R
2
= 0.362
-5
0.97
0.975
0.98
0.985
0.99
0.995
0.995
0.97
0.975
0.98
0.985
0.99
0.995
1 - NO/NOx
Fig. 1.
Log
K
p under two different RH levels in the smog chamber
0.5
Glyoxal
Methylglyoxal
0
-0.5
Dry
Wet
-1
-1.5
-2
y
= -2.8325
x
+ 0.3796
R
2
= 0.5075
-2.5
y
= -3.085
x
+ 0.796
R
2
= 0.567
-3
0
0.2
0.4
0.6
0.8
1
0
0.2
0.4
0.6
0.8
1
1.2
1 - NO/NOx
Fig. 2.
Log
K
p under high and low RH levels in the field
In the chamber, the decrease of the log
K
p value for glyoxal was 8.3 times
faster under dry conditions than under wet conditions, and only 3.6 times faster for
methylglyoxal, which is according with their solubility in water. This fact also
indicates that equilibrium between phases also depends on their evolution in time,
if we consider that in the field the aerosol is transported from central Tokyo to its
downwind regions, the results in
Table 1
can be expected, since the age of
transported aerosol increases at farther areas. Hence a different partitioning was
found at the different sites under similar atmospheric conditions.
4. Concluding Remarks
The partition coefficient of six bifunctional carbonyl compounds was calculated
from concentrations measured in the field, at an urban, a suburban and two rural
sites. Our findings include that even if the effect of variables like humidity and
