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Transcript of bao cao - in
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EIAfinal examination
Teacher: Prof. Wei
Student: Dao Thi Huyen Nhung
Student ID: R0005038
Chapter 6
Prediction and assessment of impact
on the air environment
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Air pollution:The presence in atmosphere of one or more contaminantsin such quantities and of such duration as is or tends to be injurious to
human health, animal or plant life, or property.
List of air pollutants: Gases and particulates+ Gases: such as sulfur dioxide, oxides of nitrogen, in liquid or solid by the
changing of increased pressure or decreased temperature.
+ Particulates: solid or liquid in the range of size (0.0002 m 500 m) in
diameter.
1. AIR POLLUTION
vs. KIND OF SPECIFIC AIR POLLUTANTS
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1. AIR POLLUTION
vs. KIND OF SPECIFIC AIR POLLUTANTS
Hazardous air pollutionor Air toxics: are those pollutants that areknown or suspected to cause cancer or other serious health effects, such asreproductive effects or birth defects, or adverse environmental effects.
Examples: benzene, methylene chloride, dioxin, cadmium, mercury, chromium,and lead compounds.
Photochemical smog: in the atmosphere as a result of the photo-inducereaction of hydrocarbons and oxides of nitrogen.
Acid rain: is atmospheric reaction which exhibits a pH value less than the
normal pH of rainfall (approximately 5.7 when CO2 equilibrium isconsidered) by sulfur dioxide emissions or possibly nitrogen oxide.
Other: influence of air pollution on atmospheric heat balances andassociated absorption or reflection of incoming solar radiation.
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2. SOURCES OF AIR POLLUTANTS
Emissions from industrial stacks are regulated to protecthuman and environmental health
Industrial facilities are required to obtain permits to emit intothe atmosphere and to demonstrate their compliance withregulations
Point sources (stacks)
Line sources (roads)
Area sources (treatment ponds)
Volume sources (buildings)
Biogenics
Stacks in industry, traffic
About 60% of the emissions are
from point sources
In the process of applying for permits, dispersion models are
generally used to assess the impact of point source emission
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Determine air quality impacts of alternatives and proposed
action on the mesoscale and microscale levels
The mesoscale level assessment: measures the contribution of theproposed action to area and regional emission inventories.
The microscale level assessment: is a comparison of calculatedconcentration levels of air pollutants at specific locations to applicable
ambient air quality standards.
Both levels of impact assessment are necessary in order to adequately address
the air quality impacts associated with proposed actions.
3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
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Step 1: Identification of the types and quantities of airpollutants and of their impacts
Use techniques to find Emission factors information, it indicates theaccuracy of factor with the level affects decrease (A-> E) and containsseveral conditions: Calendar year, average speed, temperature, fuelvolatility, operating modes.
Types and quantities of pollutants that will be released from the projectsources, i.e. the emission rates of all pollutants.
3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
Air quality impact assessment framework
http://www.rrcap.unep.org/male/baseline/ActnPlan/Nepal/NEPCH-B.htm
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3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
Step 2: Description of existing air quality conditions Ambient air quality data: information on air quality monitoring data.
Emission inventories: the compiled information on the quantities of airpollution from all the sources in a defined geographical area entering theatmosphere in a given time (1-yr period)
Determine meteorology and climatology: wind speed & direction, atmosphericstability classes, mixing heights, worse meteorology or a whole year of data
Step 3: Procurement of relevant air quality standards andregulations Criteria and policies will be the relevant local, state, and federal agencies
Determine the significance of air quality impacts incurred during projects; Decide between alternative actions or in assessing the need for mitigatingmeasures for a given alternative.
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Step 4: Impact prediction
Prediction and assessment of air quality impacts identify type and quantities of
air pollutants emitted from construction and operation of each alternative under
consideration for a proposed action.
3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
Identify sources of air emissions* Constructional sources
* Operational sources
Characterize air emissions: Types of air pollutants
emission rates (constant or varying)
emission heights exit temperature
exit velocity Pollution sources and their locations
Determine air sensitive receivers (ASRs) receptor locations
receptor heights (terrain heights)
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3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
Box-Model approaches: estimate of concentration values. It is based on the
mass conservation of a pollutant in a box.
The reference frame is Eulerian, i.e. fixed frame, rather than Lagrangrian, i.e.
reference frame moving with the velocity of the pollutant. The box or volume may
represent a city or region. The plan area over a city is represented by x, y and z in the
vertical dimension of the air shed.
Mass
balance approach: a mass balance of the total air pollutant emissions
from all sources for a proposed project or activity entering the atmosphere
during the construction and/or operational phase.Percentage
Increase
In inventory
=Projectactivity emission Inventory information (100)
Existing emission inventory information
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Mathematical model
+ Statistical Models: relate to air quality based on analysis of ambient air qualitymonitoring data.
+ Emission models: to predict emission rate from hazardous waste treatment anddisposal sites. The models are based on diffusion theory and emission ratesare calculated by determining the mass transfer coefficient of the pollutant.
+ Dispersion models: estimates of pollutant concentrations at selected locations.
These points of location are called receptors, and the network of points is the
receptor grid.
Adopt proven mathematical air dispersion models, for example,
VALLEY or ISCST model for stationary sources such as stack emission
CALINE4 model for traffic emission (line sources)
FDM for construction dust emission
3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
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Step 5: Assessment of impact significance Refer to the interpretation of the significance of anticipated changes related
to the proposed project.
Comparison of the combined concentration (background and incrementalconcentrations) of the pollutant and the acceptable or allowable ambient airquality standards of that pollutant.
Include publish input, professional judgment, specific effects of the types ofair pollution from a proposed project or activity.
Step 6: Identification and incorporation of mitigationmeasures
Minimize the magnitude of the air quality impacts to bring the pollutantswithin acceptable level.
Revise the design as needed in order to reduce the air pollutants expected tobe emitted from the project-activity. The revised project or activity can thenbe reassessed to determine if the mitigation measures have eliminated orsufficiently minimized the deleterious air quality
3. APPROACH FOR ADDRESSING AIR
ENVIRONMENTAL IMPACTS
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