ESCI 2610 Lecture Notes - Lecture 14: Smog, Soil Retrogression And Degradation, River Source
14 Jun 2018
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14 – Acid Pollution and Acid Deposition
Time Frame of Atmospheric Pollution
Permanent acid rain in Archean time, very little oxygen. Since then, about 3 billion years
BP, we went through a dramatic increase in the amount of oxygen. And falling levels of
carbon dioxide.
Increased emissions, mostly industrial, we see increasing amounts of air pollution and
the elements responsible for creation of acid on a regional to continental scale. The
ozone layer of the stratosphere is under attack by artificial molecules, CFCs mainly.
Photochemical smog in urban areas and acid deposition is associated with it. Nitrogen
and phosphorus turning into both wet and dry deposition.
Acid Deposition
Oxides of sulphur and nitrogen, chemical reactions (in presence of sunlight they react
with water and OH) that form H2SO4 and HNO3
They can come out as acid rain (wet deposition) or aerosol fall out (dry deposition) plus
reaction with water
N mainly atmospheric, S from fuel
Unpolluted rain with pH of 5.2-5.6, still slightly acidic because of dissolved CO2. Rain in
industrial areas can have a pH of less than 3, acid fog has a pH of less than 2. This is a
problem known in Europe since mid-1800s. dying lakes in NW Europe.
More acidic in Eastern US.
Source of Sulphur and Nitrogen Oxides
Natural and anthropogenic sources. NOx formerly from soils, lightning, atmospheric
NH3.
Forest fires exist under natural circumstances. Spread of oxides that we don’t want.
Biomass burning over 50% annual emissions of S oxides, 40% S fall out anthropogenic.
Sensitivity to acid deposition
Aquatic organisms, forest, crops, soil sensitivity to pH artificial structures affected.
Aquatic ecosystems, vulnerable systems (headwater streams, high – altitude lakes, small
lakes), leaching of Al from soils, increased fluxes into aquatic systems
Soil and forests ecosystems suffer, dieback, ozone, damage of trees soil degradation
Neutralization of acids over sedimentary rock, carbonate (neutralization) vs. crystalline
terrains (no neutralization)
Policy in Action: Emission Abatement Measure
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Document Summary
Permanent acid rain in archean time, very little oxygen. Bp, we went through a dramatic increase in the amount of oxygen. Increased emissions, mostly industrial, we see increasing amounts of air pollution and the elements responsible for creation of acid on a regional to continental scale. The ozone layer of the stratosphere is under attack by artificial molecules, cfcs mainly. Photochemical smog in urban areas and acid deposition is associated with it. Nitrogen and phosphorus turning into both wet and dry deposition. Oxides of sulphur and nitrogen, chemical reactions (in presence of sunlight they react with water and oh) that form h2so4 and hno3. They can come out as acid rain (wet deposition) or aerosol fall out (dry deposition) plus reaction with water. Unpolluted rain with ph of 5. 2-5. 6, still slightly acidic because of dissolved co2. Rain in industrial areas can have a ph of less than 3, acid fog has a ph of less than 2.
