Geology Reference
In-Depth Information
PRODUCTION
LOSS
RO 2
CH 4 , HC
j(O 1 D)
j(HONO)
j(HCHO)
j(H 2 O 2 )
O 3 + C n H 2n
j(ROOH)
j(RCHO)
j(H 2 O)
RADICAL - RADICAL
HO 2 + HO 2
HO 2 + RO 2
RO 2 + RO 2
RADICAL - NO x
OH + NO 2
HO 2 + NO 2
RO + NO Nitrate
RCO 3 + NO 2
NO
CO
HO 2
OH
NO, O 3
Heterogeneous
P
L
Figure 9 The sources, interconversions and sinks for HO x (and ROx) in the tropo-
sphere 14
Table 2 Calculated fractional contribution of various photolysis rates to radical
production with altitude
j(O( 1 D)) þ
H 2 O
j(O( 1 D)) þ
CH 4
Altitude
j(Acetone)
j(H 2 O 2 )
j(HCHO)
Ground
0.68
0.0
Neg.
0.15
0.17
Mid-
troposphere
0.52
Neg.
0.03
0.20
0.25
Upper-
troposphere
0.35
0.02
0.1
0.25
0.28
Lower
stratosphere
0.40
0.1
0.25
0.1
0.15
Note: (Neg: Negligible).
relatively high concentration given its high reactivity. The hydroxyl
radical is ubiquitous throughout the troposphere owing to the widespread
nature of ozone and water. In relatively unpolluted regimes (low NO x )the
main fate for the hydroxyl radical is reaction with either carbon monoxide
or methane to produce peroxy radicals such as HO 2 and CH 3 O 2 , viz
OH þ CO
-
H þ CO 2
(2.11)
H þ O 2 þ M
-
HO 2 þ M
(2.12)
 
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