Section #3: Water Pollution

Water Pollution the introduction of chemical, physical, or biological agents into water that degrade water quality and adversely affect the organisms that depend on the water can’t always tell if a body of water is polluted by the look or smell

Water Pollution developed countries have cleaned up their act in the past 30 years, but some waters are still at dangerous levels developing countries have a much bigger problem, mostly from sewage & agricultural runoff

Point-Source Pollution pollution that is discharged from a single source usually can be identified & traced but even when the source of the pollution is located, enforcing clean-up can be difficult

Point-Source Pollution

Nonpoint-Source Pollution pollution is coming from multiple different sources that are difficult to identify any pollution to the land in a watershed area can be carried to a river or stream from rain runoff extremely difficult to regulate or control

Nonpoint-Source Pollution

Controlling a Major Problem 96% of polluted bodies of water in the U.S. were contaminated by nonpoint sources control depends on public awareness of the effects of activities such as spraying lawn chemicals & disposing of motor oil in storm drains

Types of Pollutants pathogens – nonpoint sources (sewage, animal feces, poultry farms, wastewater treatment plants) organic matter – nonpoint sources (food waste, debris, feces, remains of dead organism) organic chemicals – nonpoint sources (pesticides, fertilizers, plastics, detergents, petroleum products, gasoline, oil) inorganic chemicals – point & nonpoint sources (acids, bases, salts, industrial chemicals) heavy metals – point & nonpoint sources (Pb, Hg, Cd, As from industrial discharge, unlined landfills, mining processes) physical agents – point & nonpoint sources (heat from industrial processes)

Wastewater water that contains waste from homes or industry carried to a wastewater treatment plant where it is filtered & treated to make the water clean enough to return to a river or lake

Treating Wastewater most of the wastewater from homes contains biodegradable material (animal & plant waste, paper, soap) that can be broken down by living organisms (like bacteria)

Wastewater Treatment Process

Sewage Sludge a product of wastewater treatment the solid material that remains after the water is treated sometimes contains dangerous levels of toxic chemicals & must be treated as hazardous waste usually burned & ash is buried in a landfill

Disposal of Sewage Sludge becoming a huge problem because the volume of sludge is enormous sludge that is not toxic can be used as fertilizer, can be combined with clay to make bricks for building, can also be used to make creative sculptures

Eutrophic Bodies of Water a build up of nutrients in a body of water (like a lake) most nutrients that enter water come from organic matter & play a key role in the aquatic ecosystem decomposition of this organic matter uses up O2 that sets up a chain reaction of events that can dramatically change the body of water

Artificial Eutrophication when human actions accelerate the natural process of eutrophication phosphorous, nitrogen, and other inorganic plant nutrients enter the water from sewage & fertilizer runoff

Algal Blooms

Thermal Pollution when the temperature of a body of water increases occurs when power plants & other industries use water in their cooling systems & then discharge the warm water back into a lake or stream warm water does not hold as much O2 as cold water does leading to suffocation & death

Thermal Pollution

Groundwater Pollution pesticides, herbicides, chemical fertilizers, & petroleum products on the land surface or in bodies of water can percolate down into the Earth & become part of the groundwater system leaking from underground storage tanks (most hold petroleum products) is another major source

Underground Storage Tanks as the tanks age, they begin to leak the location of most tanks is unknown so tanks cannot be repaired or replaced once they are located, it is often too late and the leak has spread modern tanks are contained in layers of concrete to help contain leaks

Contamination of Groundwater by Leaking Underground Storage Tanks UST Water Table Contaminating the water table

Other Sources septic tanks that leak or overflow unlined landfills that allows precipitation to seep through, carrying pollutants with it into the ground industrial wastewater lagoons that are not maintained or lined

Major Sources of Groundwater Pollution

Cleaning Up Groundwater Pollution one of the world’s most challenging problems even if we could stop all groundwater pollution this minute, the groundwater would remain polluted for 100s or 1000s of years the area is too large to completely clean pollution can cling to the rock material

Ocean Pollution too often, pollutants are dumped directly into the ocean – sometimes legally! ships are allowed to dump wastewater & garbage overboard in some parts of the ocean most of the pollution entering the ocean (oil, toxic waste, medical waste) comes from activities on land most affected areas include coral reefs, estuaries, & coastal marshes

Oil Spills oil spills make big news (think Exxon Valdez) & approximately 37 million gallons of oil from tanker accidents spills into the ocean tanker oil spills accounts for on 5% of oil in the ocean, most oil pollution comes from cities & towns & other nonpoint sources on land

Major N. Am. Oil Spills

Impact on Ecosystems some pollution can kill all living organisms for miles downstream but most pollutants do their damage after they accumulate (due to slow decomposition) biomagnification occurs & has the biggest impact on organisms at the top of the food chain

What is Biomagnification? an accumulation of pollutants (such as pesticides) at successive levels of the food chain zooplankton – small fish – medium fish – large fish – bird (or human) each organism stores the pesticide in its tissues, so at each step along the food chain, the amount of the pesticide passed on to the next organism increases

Biomagnification

Federal Laws for Improving Water Quality Clean Water Act (1972) Marine Protection, Research, & Sanctuaries Act (1972) Safe Drinking Water Act (1975) Comprehensive Environmental Response Compensation & Liability Act (1980) Water Quality Act( 1987) Oil Pollution Act (1990)

Cleaning Up Water Pollution

Cleaning Up Water Pollution