CEEN302 Exam 1

Environmental System

A defined control volume with:

1. inputs

2. outputs

3. accumulation

4. reactions

Source–Transport–Receptor Framework

Engineering causation chain linking:

1. contaminant release

2. movement

3. exposure

Multimedia Transport

Pollutant movement between air, water, soil, and biota

Steady State

accumulation equals zero

Conservative Substance

Substance that does not react or decay

Non-Conservative Substance

Substance that undergoes reaction, decay, or transformation

Black Box Model

Mass balance using boundary inputs and outputs

• does not model internal mechanisms

Box Model

• Time-dependent mass balance

• Includes accumulation and reaction

Zero-Order Reaction

Reaction rate independent of concentration

First-Order Reaction

Reaction rate proportional to concentration

Adiabatic Expansion

• Gas expansion without heat exchange

• Results in cooling

Adiabatic Compression

• Gas compression without heat exchange

• Results in heating

Clean Air Act (CAA)

Federal law regulating air emissions

Clean Air Act Amendments (1990)

Expansion adding HAPs, acid rain, and permitting programs

National Ambient Air Quality Standards (NAAQS)

Ambient limits for 6 criteria pollutants

Primary NAAQS

Air quality standards for public health

Secondary NAAQS

Air quality standards for public welfare

Criteria Pollutants

1. CO

2. NOx

3. SOx

4. O3

5. Pb

6. PM10 - PM2.5

State Implementation Plan (SIP)

State plan for achieving NAAQS

Prevention of Significant Deterioration (PSD)

Prevents air quality degradation in attainment areas

Best Available Control Technology (BACT)

Case-specific emission control in PSD areas

Lowest Achievable Emission Rate (LAER)

Most stringent control in non-attainment areas

New Source Performance Standards (NSPS)

Technology-based emission standards

National Emission Standards for Hazardous Air Pollutants (NESHAP)

Standards regulating toxic air pollutants

Hazardous Air Pollutants (HAPs)

Toxic pollutants with serious health effects

Maximum Achievable Control Technology (MACT)

Highest achievable reduction for HAP emissions

Emission Offsets

Required emission reductions in non-attainment areas

Pollutant Standards Index (PSI)

Composite public air quality indicator

Carbon Monoxide (CO)

• Binds hemoglobin

• Reduces oxygen delivery

Nitric Oxide (NO)

• Primary combustion product

• Part of ozone chemistry

Nitrogen Dioxide (NO2)

• Respiratory irritant

• Ozone precursor

Nitrogen Oxides (NOx)

Collective term for NO and NO2

Sulfur Dioxide (SO2)

Acid-forming combustion gas

Sulfur Oxides (SOx)

Collective sulfur-containing combustion gases

Ozone (O3)

Secondary pollutant formed by NOx and VOC reactions

Volatile Organic Compounds (VOCs)

Reactive organic gases participating in smog formation

Photochemical Smog

Ozone-rich urban pollution formed under sunlight

Photochemical Oxidants

Ozone and related secondary oxidizing compounds

Lead (Pb)

Neurotoxic heavy metal

Particulates

Suspended solid or liquid airborne particles

Particulate Matter (PM10)

• Inhalable particles ≤10 micrometers

• only reach top of lungs

Particulate Matter (PM2.5)

• Fine particles ≤2.5 micrometers

• reach deep into the lungs

Respirable Suspended Particulates (RSP)

Fine particles capable of reaching alveoli

Aerodynamic Diameter

Equivalent particle size determining settling behavior

Material Effects of Air Pollution

Surface degradation by:

1. Abrasion: Mechanical surface wear from impacting airborne particles

2. Deposition: Settling and accumulation of pollutants on surfaces

3. Chemical Reaction: Pollutants chemically alter material composition

4. Corrosion: Electrochemical metal degradation from pollutants and moisture

Vegetation Effects

Ozone and acids damage plant tissue

Health Effects of Air Pollution

Respiratory, cardiovascular, and neurological impacts from pollutant exposure

Indoor Air Pollution

Pollution buildup inside buildings from combustion and materials

Indoor CO Sources

• Gas appliances

• incomplete combustion

Indoor NOx Sources

• Gas burners

• heaters

Formaldehyde (CH2O)

Volatile irritant emitted from building materials

Radon (Rn)

Radioactive soil gas entering homes

Air Changes per Hour (ACH)

Ventilation rate = airflow/volume

Acid Rain

Deposition of sulfuric and nitric acids

Ozone Depletion

Stratospheric ozone breakdown increasing UV exposure

Greenhouse Effect

Atmospheric trapping of infrared radiation

Atmospheric Engine

Global circulation driven by solar heating

Mechanical Turbulence

Turbulence caused by surface friction

Thermal Turbulence

Turbulence caused by buoyant heating

Atmospheric Stability

Atmosphere’s resistance to vertical motion

Lapse Rate

Rate of temperature change with elevation

Dry Adiabatic Lapse Rate

Reference rate for neutral atmospheric stability

Temperature Inversion

Stable layer trapping pollutants near surface

Terrain Effects

Topography influencing dispersion

Heat Island Effect

Urban warming altering local stability

Land/Sea Breeze

Local circulation caused by differential heating

Valley Effects

Inversion and pollutant trapping in valleys

Atmospheric Dispersion

Transport and dilution of pollutants

Advection

Horizontal pollutant transport by wind

Diffusion

Turbulent spreading of pollutants

Gaussian Dispersion Model

Model estimating downwind concentration from point source

Effective Stack Height

Physical stack height plus plume rise

Plume Rise

Increase in plume elevation from buoyancy and momentum

σy

Horizontal dispersion parameter

σz

Vertical dispersion parameter

Building Downwash

Structures forcing plume downward

Fumigation

High ground concentrations when inversion breaks

Lofting

Plume dispersion upward above stable layer

Woburn, Massachusetts

Working-class Boston suburb where groundwater contamination led to childhood leukemia litigation

Anne Anderson

Mother who initiated investigation into contaminated municipal wells

Jan Schlichtmann

Plaintiffs’ attorney who pursued corporations despite financial risk

Childhood Leukemia Cluster

Twelve leukemia cases in small population statistically elevated above expected rates

Wells G and H

Municipal groundwater wells shut down in 1979 after solvent contamination detected

Primary Contaminants in Wells

1. Trichloroethylene

2. Perchloroethylene

Trichloroethylene (TCE)

Chlorinated degreasing solvent found in municipal wells and later classified as carcinogenic

Perchloroethylene (PCE)

Dry-cleaning and industrial solvent detected in Woburn groundwater

Chlorinated Solvents in Groundwater

Persistent dense compounds capable of long-term subsurface contamination

Cryovac Facility

Beatrice Foods subsidiary accused of dumping solvent waste

UniFirst Corporation

Industrial laundry accused of improper solvent disposal

Aberjona River Watershed

Industrialized valley influencing groundwater flow near municipal wells

Pre-RCRA Waste Practices

Unregulated solvent disposal prior to 1976 hazardous waste law

Resource Conservation and Recovery Act (1976)

Federal hazardous waste law enacted after widespread disposal problems

Groundwater as Drinking Water Source

Municipal supply dependent on local aquifer vulnerable to contamination

Cone of Depression

Pumping lowered groundwater levels around Wells G and H

Capture Zone

Region of groundwater flow drawn toward pumping wells

Fractured Bedrock Hydrogeology

Groundwater moved along discrete fractures rather than uniform porous media

Anisotropic Flow

Different permeability in different directions, complicating plume modeling

Hydraulic Conductivity Variability

Spatial permeability differences, affecting contaminant travel speed

Advection (Groundwater)

Solvents transported primarily by bulk groundwater movement

Mechanical Dispersion

Spreading of plume due to velocity variations within fractures