第二章 大气环境化学.pdf

《环境化学》第二章大气环境化学
第二章第二章
大气环境化学大气环境化学
EnvironmentalEnvironmental chemistrychemistry
inin AtmosphereAtmosphere
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《环境化学》第二章大气环境化学
第一节第一节
大气的组成及其主要污染物大气的组成及其主要污染物
一、大气的主要成分
二、大气层的结构
三、大气中的主要污染物
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《环境化学》第二章大气环境化学
一、大气的主要成分
positions in atmosphere
大气的主要成分(体积百分比)包括:
ƒ N2(%)、 O2(%)、 Ar(%)和CO2
(%)。
ƒ 几种惰性气体:He(×10-4)、Ne(×10-3)、
Ke(×10-4)和Xe(×10-6)的含量相对比较高。
ƒ 水的含量是一个可变化的数值。一般在1~3%。
-5 -4
ƒ 痕量组分,如H2(5×10 )、CH4(2×10 )、CO
-5 -7 -7
(1×10 )、SO2(2×10 )、NH3(6×10 )、N2O
-5 -6 -6
(×10 )、NO2(2×10 )、O3(4×10 )等。
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《环境化学》第二章大气环境化学
Atmospheric Trace Gases in Dry Air Near Ground Level
Gas or Volume Process for Removal
Species Percenta Major Sources from the Atmosphere
-4 b
CH4 ×10 Biogenic Photochemical
CO ~×10-5 Photochemical, Photochemical
-5
N2O 3×10 Biogenic Photochemical
d -10 -6
NOX 10 to 10 Photochemical, lightning, anthrogenic Photochemical
-9 -7
HNO3 10 to 10 Photochemical Washed out by precipitation
-8 -7
NH3 10 to 10 Biogenic Photochemical, washed out by precipitation
-5
H2 5×10 Biogenic, Photochemical Photochemical
-8 -6
H2O2 10 to 10 Photochemical Washed out by precipitation
HO·e 10-13 to 10-8 Photochemical Photochemical
e -11 -9
HO2· 10 to 10 Photochemical Photochemical
-8 -7
H2CO 10 to 10 Photochemical Photochemical
-9 -8
CS2 10 to 10 Anthropogenic, biogenic Photochemical
OCS 10-8 Anthropogenic, biogenic, photochemical Photochemical
-6
SO2 ~2×10 Anthropogenic, photochemical, volcanic Photochemical
I2 O trace - -
f -5
CCl2F2 ×10 Anthropogenic Photochemical
g -8
l3 ~1×10 Anthropogenic Photochemical
a Level in the absence of gross pollution; b From biological sources; c Sources arising from human activities; d
e
Sum of NO, NO2, and NO3, of which NO3 is a major reactive species in the atmosphere at night; Reactive free
radical species with one unpaired electron, transient species whose concentrations e much lowe