SECTION 3: WATER POLLUTION CHAPTER 11- WATER

WATER POLLUTION Definition: the introduction of chemical, physical, or biological agents into water that degrades water quality and adversely affects the organisms that depend on the water 2 underlying causes: Industrialization  cause for pollution in developed countries Rapid human population growth 2 sources of water pollution: Point-source Nonpoint-source

POINT-SOURCE POLLUTION Definition: pollution that is discharged from a single source Can be identified and traced to the source Enforcing clean up can be difficult Sources: Leaking septic-tank systems Leaking underground storage tanks that contain chemicals or fuels (ex. gasoline) Leaking oil tanker Polluted water from abandoned and active mines Water discharged by industries Public and industrial wastewater treatment plants

POINT-SOURCE POLLUTION

NONPOINT-SOURCE POLLUTION Definition: comes from many different sources that are often difficult to identify Difficult to regulate and control because it comes from many different sources and enters that water in various ways Cause for 96% of contaminated water in the US Controlling it depends on human awareness of their actions

NONPOINT-SOURCE POLLUTION Sources: Chemicals added to road surfaces  salt and de-icing agents Runoff from city and suburban streets  contain oil, gasoline, animal feces, litter Pesticides, herbicides, and fertilizer from lawns, golf courses, and farmland Feces and agricultural chemicals from livestock feedlots Precipitation containing air pollutants Soil runoff from farms and construction sites Oil and gasoline from personal watercraft

NONPOINT-SOURCE POLLUTION

Type of pollutantAgentMajor Sources Pathogens Disease-causing organisms  bacteria, viruses, protozoa, parasitic worms Mostly nonpoint sources  sewage or animal feces, livestock feedlots, and poultry farms; sewage from overburdened wastewater treatment plants Organic matter Animals and plant remains; feces, food waste, and debris from food-processing plants Most nonpoint sources Organic chemicals Pesticides, fertilizers, plastics, detergents, gasoline and oil, other materials made from petroleum Mostly nonpoint  farms, lawns, golf courses, roads, wastewater, unlined landfills, leaking underground storage tanks Inorganic chemicals Acids, bases, salts, industrial chemicals Point and nonpoint  industrial waste, road surfaces, wastewater, polluted precipitation Heavy metals Lead, mercury, cadmium, arsenicPoint and nonpoint  industrial discharge, unlined landfills, some household chemicals, mining processes; can occur naturally in groundwater Physical agents Heat and suspended solidsPoint and nonpoint  heat from industrial processes and suspended solids from soil erosion

WASTEWATER Definition: water that contains wastes from homes or industry Needs to go to a wastewater treatment plant to be filtered and treated Ensures that it is clean enough to return to a river or lake

WASTEWATER TREATMENT Primary treatment Filtration- wastewater is passed through a large screen to remove solid objects First settling tank- wastewater sent to a large tank where smaller particles sink to the bottom and form sewer sludge which gets removed Sewer sludge contains dangerous concentrations of toxic chemicals  must be disposed of as hazardous waste by being incinerated (burnt) and then buried in a landfill Sludge can be reduced to safe levels  used as fertilizer or combined with clay to make bricks

WASTEWATER TREATMENT Secondary treatment Aeration tank- wastewater is mixed with oxygen and bacteria The bacteria use the oxygen to feed on the waste Second settling tank- bacteria grown in the aeration tank and other solid wastes are removed in the form of sludge Chlorination- chlorine is added to disinfect the water before it’s released into a stream or ocean

EUTROPHICATION Most nutrients in the water come from organic matter  leaves and animal wastes that is broken down by decomposers Decomposers release the nutrients (minerals) inside the leaves and animals Decay and decomposition uses up oxygen in water Eutrophication- an increase in the amount of nutrients in a body of water Typically occurs in lakes and slow-moving streams As a body of water becomes more eutrophic  plants take root in the bottom and the shallow waters fil in creating swamps and marshes

ARTIFICIAL EUTROPHICATION Definition: eutrophication caused by humans Natural eutrophication gets accelerated by inorganic plant nutrients  nitrogen and phosphorous Enters water from sewage and fertilizer runoff Fertilizers from lawns, farms, and gardens are the largest source of nitrogen and phosphorous

ARTIFICIAL EUTROPHICATION Phosphorus is a plant nutrient that can cause excessive growth of algae Algal blooms form  large floating mats of algae Dissolve oxygen is used as the algae dies and decomposes which causes fish and other marine organisms to suffocate and die

THERMAL POLLUTION Definition: a temperature increase in a body of water that is caused by human activity Has a harmful effect on water quality Has a harmful effect on the ability of that body of water to support life Causes large fish kills  large amount of fish population die all at one time and

THERMAL POLLUTION Occurs when power plants and other industries use water from a lake or river for their cooling systems and then discharge the water back to the source As temperature of the water increases  the amount of oxygen in the water decreases Lack of oxygen in the water causes marine organisms to suffocate and die

GROUNDWATER POLLUTION Occurs when polluted surface water percolates down into the groundwater Most common pollutants: Pesticides Herbicides Chemical fertilizers Petroleum products

GROUNDWATER POLLUTION Major source: leaking underground storage tanks Storage tanks are located beneath gas stations, farms, and homes Hold petroleum products  gasoline and fuel As they age, develop leaks which allow toxins to seep into the groundwater Location is not always known until a large amount of pollutant has seeped out

GROUNDWATER POLLUTION One of the most challenging environmental problems Groundwater recharges slowly  difficult to filter out the pollutants Aquifers can take hundreds of years to recycle water and get ride of contaminants Difficult to decontaminate groundwater  water is dispersed throughout large areas of rock and sand Pollutants cling to rock and sand

OCEAN POLLUTION Caused by pollutants going into the ocean Pollutants can be dumped directly into the ocean In some parts of the ocean, ships can directly dump wastewater and garbage overboard 85% of pollution comes form activities on land Oil Toxic waste Medical waste

OCEAN POLLUTION Polluted rivers carry pollutants to oceans Most activities that pollute oceans occur near the coast Can be from accidental oil spills Approximately 37 million gallons of oil from oil tankers are spilled into the ocean Only responsible for 5% of ocean pollution Most of oil that pollutes the ocean from cities and towns from nonpoint sources on land

WATER POLLUTION & ECOSYSTEMS Many pollutants accumulate in the environment because they do not decompose quickly Water pollution can cause immediate damage to an ecosystem Biomagnification: accumulation of pollutants at successive levels of the food chain Serious consequences for organisms at the top of the food chain Reason for US states limiting the amount of fish that people can eat from certain bodies of water

CLEAN WATER ACT OF 1972 Purpose: to “restore and maintain the chemical, physical, and biological integrity of the nation’s waters” Came as a result of the Cuyahoga River in Cleveland, Ohio, catching fire Paved the way for other water-quality legislation