Unit 3: Pollution Environmental 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

7 Pollution Sources Point sources are direct discharges to a single point;

8 Pollution 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).

17 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).

24 EPA Criteria air pollutants Nitrogen Dioxide: NO 2 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 O 3 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

25 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: SO 2 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).

28 Comparison of 1970 and 1999 Emissions