Environmental Engineering Reference
In-Depth Information
HSO
+
0.5O
→
HSO
23
2
24
HSO
+
CaCO
+
2HO 0.5O
+
→
CaSO.2HO HCO
+
24
3
2
2
4 2
2 3
These processes have been studied by Baedecker
et al.
[BAE 92] on the
limestones and marbles at five American sites, within the framework of the NAPAP
(National Acid Precipitation Assessment Program). The erosion speed is far more
important for limestone (25-45 µm/year) than for marble (15-30 µm/year). Thirty
per cent of the erosion is due to dry and wet sulfur deposits and 70% is due to simple
karstic dissolution of calcite by rain water.
The UN-ECE program run by United Nations for Europe studied 39 sites in 11
countries, allowing the evaluation of average annual SO
2
content (µg/m
3
) acceptable
for different materials. Unexpectedly, nickel (2 µg/m
3
), bronze (17.9 µg/m
3
), and
even limestone (18.5 µg/m
3
) have lower thresholds than human beings (50 µg/m
3
).
8.3.3.2.
Impact of particulate pollution
The atmosphere contains solid and liquid particles in suspension, the diameter of
which ranges from some angstroms to 100 µm. The speed at which they fall may be
very slow. The natural sources of atmospheric aerosols are mainly oceans, deserts,
biological sources and volcanoes (see Table 8.9). Industrial combustion, domestic
heating and incineration of domestic garbage, transportation and vegetation fires are
the predominant anthropogenic sources [REN 96].
Natural origins
Quantity (megatons/year )
Extraterrestrial
10-18
Marine (halite, gypsum)
1,000-10,000
Deserts
500-2,000
Biological, biogenic
80
Volcanic
25-250
Others
345-1,100
Anthropogenic origin
Direct emission by man
10-90
Carbon-containing dusts,
nitrates and sulfates
175-325
Forest and savannah fires
3-150
Table 8.9.
Quantities of dust with a radius below 100 µm emitted
in one year by different sources [REN 96]
