Environmental Engineering Reference
In-Depth Information
Table 8.1
Most common emissions with regional and local impact and
their primary effects resulting from animal production.
Emission
Concern
Scale
Global/Regional
Local
NH
3
Atmospheric deposition
Major
Minor
N
2
O
Global climate change
Significant
Insignificant
NOx
Haze
Significant
Minor
CH
4
Global climate change
Significant
Insignificant
VOCs
Quality of human life
Minor
Minor
H
2
S
Quality of human life
Insignificant
Significant
PM
10
Haze
Insignificant
Significant
PM
2.5
Health, haze
Insignificant
Significant
Odor
Quality of life
Insignificant
Major
CH
4
, methane; H
2
S, hydrogen sulfide; NH
3
, ammonia; N
2
O, nitrous oxide; NOx,
nitrogen oxides; PM, particulate matter; VOCs, volatile organic compounds.
From National Research Council of the National Academies (NRC), 2003.
Secondary pollutants are not directly emitted from a source but are instead formed in the
atmosphere by chemical reactions. Examples of secondary pollutants are ground-level ozone,
sulfur trioxide (SO
3
), sulfuric acid (H
2
SO
4
), nitric acid (HNO
3
), ammonium nitrate, and
ammonium sulfate (“Sources of pollutants in the ambient air,” n.d.).
Emissions with local and regional impact
Air pollutants are substances high enough in concentration to cause negative environmental
effects. They may be the result of biogenic (produced by living organisms or biological
processes) or anthropogenic (result of human activity) processes. In this section, only the
emissions from anthropogenic sources will be covered, and because the most common air
pollutants have the potential to cause both local and regional impacts they will be treated
together in this section (Table 8.1).
Primary pollutants with impact at local and regional levels are sulfur dioxide, nitrogen
oxides, carbon monoxide, particle matter, and VOCs. These five pollutants along with lead,
sulfur trioxide, and ozone are called “criteria pollutants” by the EPA to differentiate them
from other hazardous air pollutants that will not be covered in this chapter. Emissions of
another two compounds, as a result of food processing, that may act as local and regional
pollutants are ammonia and hydrogen sulfide. In addition the emission of odors, which are
VOCs with the inclusion of sulfur, also create environmental problems on a local scale.
Sulfur dioxide
Sulfur dioxide is primarily a by-product of the combustion of fuels that contain sulfur com-
pounds, such as coal, oil, and high-sulfur diesel. Sulfur dioxide is transformed into sulfur tri-
oxide in the atmosphere, then combines with water to produce sulfuric acid, a component of
acid rain (“Sources of pollutants in the ambient air,” n.d.).
Nitrogen oxides
Nitrogen oxide is a generic name to describe nitric oxide and nitrogen dioxide; however, it
may include other oxides of nitrogen. In the atmosphere, in the presence of light, these two
compounds are in equilibrium:
