60
J. M. Prospero
Table 2.3. Emissions of nitrogen species to the atmosphere (Pro spero et al. 1996)
Source
NO x (Tg N yr-')
Lightning
Soils (and crops)
Biomass burning
Stratospheric injection
Energy prod uction
Aircraft
Total
NH.(Tg N yr-')
Ocean
Soils (and fertilizer)
Biomass burning
Animal excretia
Total
Pre-industrial
3
3.6
0.8
0.6
0
0
8.0
3-13
10
0.5
2.5
16-26
Present day
3
5.5
8.5
0.6
21.3
0.5
39.4
3-13
20
5
32
60-70
Anthropogenic
1.9
7.7
21.3
0.5
31.4
10
4.5
29.5
44
low over the oceans except for those regions close to coastal urban complexes that emit
large quantities of pollutants. However, pollutants do have a substantial impact on the
NO x chemistry of the remote ocean through PAN. PAN is quite stable at cold temperatures - it has a lifetime of months at 250 K - but it decomposes rapidly at typical ambient temperatures. PAN produced in polluted continental regions can be transported
long distances through the upper troposphere; when it is brought down to the surface, it decomposes to produce NOx; subsequent reactions produce the usual end product, HN03. PAN along with lightning and transport from the stratosphere are the major sources of NO x over the ocean (see Table 2.3); in many ocean areas, PAN pollution
sources completely dominate natural sources.
As shown in Table 2.3, human activities have had a great impact on the mobilization of NH3 and NHt (Galloway et al. 1995; Bouwman et al. 1997; Benkovitz et al. 1996).
The production of fertilizer converts about 80 Tg N yr- 1 from N z to NH3 with an annual rate of increase of 5.3% per year (Galloway et al. 1995); a substantial fraction of
this NH3 (about 10 Tg N yr- 1 ) is volatized directly from fertilized fields (Dentener and
Crutzen 1994). The largest single source of ammonia (about 30 Tg Nyr- 1 ) is from the
excreta of domesticated animals; this source is estimated to be much greater today
(about a factor of ten) than in preindustrial times because of the greatly increased
world population and because of the increased consumption of meat in the diet
(Dentener and Crutzen 1994; Prospero et al. 1996). Emissions of NH3 from biomass
burning have also greatly increased, although amounts are only modest in the overall
budget (Dentener and Crutzen 1994). The present day emissions ofNH x (including both
natural and anthropogenic sources) is about 60-70 Tg Nyr- 1 (Prospero et al. 1996). The
total present-day emissions for both NO x and NHx is about 100-110 TgNyr- 1 (Table 2.3).
Total preindustrial emission rates were about 24-34 Tg N yr- 1 • Considering all conti-
J. M. Prospero
Table 2.3. Emissions of nitrogen species to the atmosphere (Pro spero et al. 1996)
Source
NO x (Tg N yr-')
Lightning
Soils (and crops)
Biomass burning
Stratospheric injection
Energy prod uction
Aircraft
Total
NH.(Tg N yr-')
Ocean
Soils (and fertilizer)
Biomass burning
Animal excretia
Total
Pre-industrial
3
3.6
0.8
0.6
0
0
8.0
3-13
10
0.5
2.5
16-26
Present day
3
5.5
8.5
0.6
21.3
0.5
39.4
3-13
20
5
32
60-70
Anthropogenic
1.9
7.7
21.3
0.5
31.4
10
4.5
29.5
44
low over the oceans except for those regions close to coastal urban complexes that emit
large quantities of pollutants. However, pollutants do have a substantial impact on the
NO x chemistry of the remote ocean through PAN. PAN is quite stable at cold temperatures - it has a lifetime of months at 250 K - but it decomposes rapidly at typical ambient temperatures. PAN produced in polluted continental regions can be transported
long distances through the upper troposphere; when it is brought down to the surface, it decomposes to produce NOx; subsequent reactions produce the usual end product, HN03. PAN along with lightning and transport from the stratosphere are the major sources of NO x over the ocean (see Table 2.3); in many ocean areas, PAN pollution
sources completely dominate natural sources.
As shown in Table 2.3, human activities have had a great impact on the mobilization of NH3 and NHt (Galloway et al. 1995; Bouwman et al. 1997; Benkovitz et al. 1996).
The production of fertilizer converts about 80 Tg N yr- 1 from N z to NH3 with an annual rate of increase of 5.3% per year (Galloway et al. 1995); a substantial fraction of
this NH3 (about 10 Tg N yr- 1 ) is volatized directly from fertilized fields (Dentener and
Crutzen 1994). The largest single source of ammonia (about 30 Tg Nyr- 1 ) is from the
excreta of domesticated animals; this source is estimated to be much greater today
(about a factor of ten) than in preindustrial times because of the greatly increased
world population and because of the increased consumption of meat in the diet
(Dentener and Crutzen 1994; Prospero et al. 1996). Emissions of NH3 from biomass
burning have also greatly increased, although amounts are only modest in the overall
budget (Dentener and Crutzen 1994). The present day emissions ofNH x (including both
natural and anthropogenic sources) is about 60-70 Tg Nyr- 1 (Prospero et al. 1996). The
total present-day emissions for both NO x and NHx is about 100-110 TgNyr- 1 (Table 2.3).
Total preindustrial emission rates were about 24-34 Tg N yr- 1 • Considering all conti-