Environmental Engineering Reference
In-Depth Information
Volcanic bombs
Volcanic ash cloud
Inactive volcanic cone
Fumaroles
Crater
Adventive cone
Volcanic cone
Solidified
lava flows
Lava flows
Magma chamber
Fig. 2.1 Intuitive representation of active and inactive volcanic phenomena [ 17 ]
Table 2.1 Approximate composition of volcanic gas [ 18 - 21 ]
Component H 2 O 2
SO 2
H 2 S
COS
CS 2
HCl
HBr
HF
10 4 -10 2
10 4 -
10 2
10 4 -
10 2
10 3
% vol
50-90
1-40
1-25
1-10
1-10
<
As hydrochloric acid is highly soluble in water, it is quickly removed from the
atmosphere through acid rains that usually start during eruptions, when water
vapour condenses on cooled ash particles, in higher atmospheric layers.
Hydrosulphuric acid has the same contribution, after it is oxidised by the ozone
in the troposphere:
H 2 S
þ
2O 3 !
H 2 SO 4 þ
O 2
ð
2
:
1
Þ
The hydrobromic acid (HBr) concentration is relatively low [ 22 , 23 ]. However,
its contribution, alongside hydrosulphuric acid oxidation, is significant for the
direct decrease in both the ozone and the diatomic oxygen concentration, as it
forms derivatives with the diatomic oxygen much easier than the hydrochloric acid:
HBr
þ
O 3 !
HBrO 3
ð
2
:
2
Þ
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