Water Chapter 5 Part II

II. Freshwater Pollution A. Water pollution is the introduction of chemical, physical, or biological material into the water which degrades the water quality and affects the organisms that live in it or drink it. 1. In some countries, the main problem is industrial and agricultural pollution that are not controlled by the government 2. In very poor countries, the population is too big and water is often polluted by sewage and agriculture. 3. As we see here, the two underlying causes of water pollution are: a. industrialization b. human population explosion

B. Point pollution is pollution that is discharged from a B. Point pollution is pollution that is discharged from a single source examples:factory; waste treatment plant; oil tanker…) 1. Easy to regulate and control because it can be identified 2. May still be difficult to enforce and clean up C. Nonpoint pollution is pollution that comes from many sources, not just one specific site. 1. Runs into waterways from streets and storm sewers 2. Can come from homes, lawns, farms, highways, almost anywhere. 3. Extremely difficult to control and regulate a. 96% of polluted bodies of water in the U.S. are contaminated by nonpoint sources b. educating the public will be the most effective solution.

D. Wastewater Treatment Plants 1. Most of the water that goes down the drain (waste water) goes to a treatment plant a. water is treated before being returned to a river or lake b. fig 5-21 on page 135 is of a treatment plant. 2. Treatment plants cannot remove all harmful substances a most wastewater from homes is biodegradable and easy to purify b. industrial waste water and storm runoff from streets and fields contain toxic substances that interfere with treatment

3. One of the products of wastewater 3. One of the products of wastewater treatment is sludge = the solid material left after treatment a. Contains dangerous, toxic chemicals, so it is usually disposed of as hazardous waste. b. it is often incinerated then buried in a secure landfill c. it is so expensive to deal with that communities are making it less toxic so it can be used: i. can be used as fertilizer ii. can be combined with clay to make bricks

E. Pathogens are disease causing organisms examples: bacteria, viruses, parasitic worms 1. Can enter water supplies in untreated waste water or anima feces 2. Many diseases are caused by drinking pathogen polluted water examples: cholera, hepatitis, tyohoid, etc. 3. Public water suppies are routinely checked for pathogens. example: fecal coliform test to look for E. Coli bacteria

F. How Water Pollution Affects Ecosystems 1. Water pollution can affect all levels of the food chain a. Toxins may get into the tissues of organisms b. At each step in the food chain, the amount of toxin passed to the next “eater” increases = biological magnification example: Toxins get into the tissues of a tiny, river- bottom organism; one small fish eats hundreds of these organisms; one big fish eats hundreds of the contaminated small fish; an eagle eats ten of the contaminated big fish. The toxin is building up at each level. 2. Water pollution can cause immediate damage to an ecosystem example: spills of tixic chemicals directly into a river can kill nearly all living things for miles downstream

3. Water pollution can be harmful to human health a. toxins in fish tissues can make it too dangerous for humans to eat. b. some heavy metals and toxic chemicals in waterways cause cancer or birth defects; affect reproduction;damage the nervous system, liver or kidneys

G. Artificial Eutrophication = eutrophication caused by humans 1. When a lake or stream becomes eutrophic, they contain lots of nutrients a. occurs naturally over a long period of time b. organisms die, decomposers use oxygen to break them down into nutrients, plants grow in the nutrient rich shallows, fish and other organisms die because of lack of oxygen eventually, a marsh or swamp forms. 2. The process speeds up when plant nutrients ( N and P) get into the water from sewage and fertilizer runoff. a. phosphorus (P) in detergents, animal waste, and fertilizer cause algal blooms which lead to eutrophication b. some states have banned or limited phosphate detergents

H. Thermal Pollution occurs when excessive amounts of heat are added to a body of water. 1. Occurs when power plants and industries along lakes or rivers use water in their cooling systems. a. cool water is pulled from the lake or river to absorb heat from engines. b. warm water is returned to the lake or river. 2. Can cause fish kills if it is too warm for the fish 3. Warm water cannot hold as much oxygen, so some organisms suffocate. 4. If it is continuous, the whole ecosystem may be changes because some organisms could not adjust to the higher temperatures 5. Citizens often oppose power plants on lakes and rivers and insist the water be cooled before it is put back into a waterway.