Unit 3: PollutionEnvironmental Science

Water Sources

• Surface Water: fresh water on the Earth’s land surface (lakes, rivers, streams and wetlands).• River Systems: network of water formed by streams/rivers.• Watershed: the area of land drained by a river.

• Groundwater: found beneath the Earth’s surface.• Aquifer: underground formation that holds groundwater.

Groundwater Details

• Groundwater accumulates because most rocks are porous (small holes).• Permeable: allows substances (water) to flow through it.• Impermeable: does not allow water to flow through

(clay/granite).

• Water seeps down from the surface (percolation) through a recharge zone.• Very sensitive areas, pollution in a RZ can lead to pollution

in groundwater supplies.

• Wells: a hole dug/drilled to reach groundwater.

Water Pollution

• Any introduction of chemical, physical, or biological agents into water that degrades water quality.• Adversely affect organisms that depend on water.

• 2 underlying causes of water pollution:• Industrialization• Human population growth

Types of water pollution

• 3 Types:• Biological: Bacteria, viruses, parasites• Chemical: Heavy metals (arsenic/mercury), pesticides,

fertilizers• Physical: Sediment (dirt), heat

7Pollution Sources

• Point sources are direct discharges to a single point;

8Pollution Sources

• Non-point sources are diffused across a broad area and their contamination cannot be traced to a single discharge point.

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Point Pollution Control

• Recycling:• Reduces resources needed to produce products.

• Minimize waste production:• Manufacturing technology/techniques.

• Prevention:• Process wastes before discharging into water source.

Non-Point Pollution Control

• Buffer Strips:• Grass planted between pavement/crop fields that can absorb

runoff before it gets to water source.

• Retention Ponds:• Built in drainage areas to collect runoff and let

contaminants settle out before reaching water source.

• Reduce Pesticide Use (IPM):• Biological pest control – Use bugs/animals to eat pests

Eutrophication

• Excessive plant/algal growth due to increased nutrient levels in water.

• Natural process (erosion) • Accelerated by human activities.• Caused by phosphate rich fertilizer/sewage runoff.• Cause algae blooms (increased # of algae) which may lead

to hypoxia, which is a decreased amount of dissolved oxygen in the water = dead aquatic organisms.

Groundwater Pollution

• Groundwater pollution is difficult to clean up.• Dispersed throughout a large area of rock.• Pollutants can cling to materials that make up an aquifer.

• Filter/process at source of extraction (expensive equipment/technology).

Oil Pollution

• Several large oil spills over years (Exxon/Valdez, Gulf spill etc.)

• Major effects:• Poison wildlife/fish• Spread quickly by weather conditions• Long time for natural clean-up (oil-eating bacteria)

Air Pollution

• Forms of air pollution:• Primary pollutant: directly from human activity (soot from

smoke).• Secondary pollutant: primary pollutants react w/ naturally

occurring substances such as water vapor (smog).

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Air pollutant impacts

• Greenhouse effect• Ozone depletion• acidification • smog formation• eutrophication • human health• ecosystem health

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Smog

• Smog results from chemical reactions involving sunlight, air, exhaust and ozone.• Pollutants released from vehicles and industries are the

main causes of smog.

Temperature Inversion

• Normal circulation of air keeps pollutants from building up to dangerous levels.

• Usually air decreases in temp as altitude increases: A temperature inversion occurs when the air above is warmer than the air below.• Traps cool air along with any pollutants (greater chance of

occurring in a valley: LA).

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EPA Criteria air pollutants

• Nitrogen Dioxide: NO2

• brownish gas irritates the respiratory system originates from combustion (N2 in air is oxidized); NOx sum of NO, NO2, other oxides of N

• Ozone: ground level O3

• primary constituent of urban smog• reaction of VOC + NOx in presence of heat +sun light

• Carbon monoxide: CO• reduces bloods ability to carry O2 • product of incomplete combustion

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• Lead: Pb • cause learning disabilities in children , toxic to liver, kidney, blood

forming organs• tetraethyl lead – anti knock agent in gasoline• leaded gasoline has been phased out

• Particulate Matter: PM10 (PM 2.5) • respiratory disorders

• Sulfur Dioxide: SO2

• formed when fuel (coal, oil) containing S is burned and metal smelting• precursor to acid rain along with NOx

Controlling MV Emissions

• The Clean Air Act (1970) gives the EPA authority to regulate vehicle emissions in the US.• Lead gas was eliminated (90% decrease in 30 yrs)• Catalytic converters required on automobiles (clean air gas

exhaust before exits tailpipe).

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Comparison of 1970 and 1999 Emissions