Water Pollution Miller Chapter 21

Water Resources Water is a “renewable” but finite resource Clean water is essential to human/animal health – humans can only live about 3 days without water

“Water Planet” About 70% of Earth’s surface is water 97.5% of that is ocean water 2.5% is fresh water 1.5% is frozen in ice caps & glaciers 0.5% is inaccessible/brackish Only about 0.02% of the Earth’s water supply is available as liquid freshwater

Who is using Earth’s water resources? What 2 conclusions can you draw from this data?

Hydrological Cycle

Transpiration – from plants Evaporation – from rivers, lakes, ponds, oceans Precipitation – rain Runoff – to rivers, lakes, etc Infiltration/Seepage – to aquifers, groundwater, to rivers & oceans, to plants

Surface Water Surface water is water that is above ground in lakes, rivers, ponds, and streams A watershed is the entire area of land that is drained by a river

Fig. 14-3, p. 308 Unconfined Aquifer Recharge Area Precipitation Evaporation and transpirationEvaporation Confined Recharge Area Runof f Flowing artesia n well Recharge Unconfined Aquifer Stream Well requiring a pump Infiltration Water table Lake Infiltration Unconfined aquifer Confined aquifer Confining impermeable rock layer Less permeable material such as clay

Groundwater and Aquifers Groundwater – water that seeps down into the soil and is stored underground Aquifers – large amounts of water in underground rock formations Ex. Edward’s Aquifer (TX)

Aquifers Aquifers are running low – people are pumping too much out! It can take millions of years to form Recharge zone: area of land from which groundwater originates

Freshwater Pollution the introduction of chemical, physical, or biological material into water that degrades the quality of the water and affects the organisms that drink it and live in it.

Major Water Pollutants and Their Sources

Common Diseases Transmitted to Humans through Contaminated Drinking Water

Point Pollution pollution that is discharged from a single source, such as a factory, a wastewater treatment plant, or an oil tanker

Point Pollution Fairly easy to identify, regulate, and control Ex: septic tanks, storage lagoons for polluted waste, landfills, underground gasoline storage tanks, wastewater treatment plants, industrial plants

Nonpoint Pollution Pollution that comes from many sources Reaches bodies of water via streets and sewers Accumulation of small amounts of pollution adds up to huge problems Hard to regulate and control – mostly public awareness is only help

Nonpoint Pollution Ex: highway construction and maintenance; oil, gasoline, dog feces, litter from storm drain runoff; pesticides and fertilizer; dry salt (for snow and ice on roads)

Major kinds of water pollution Pathogens – disease causing organisms such as bacteria; caused by untreated human sewage entering water Organic matter – biodegradable remains of animals and plants, including feces; mainly nonpoint sources

Water Pollution Organic chemicals – pesticides, fertilizers, plastics, detergents, gasoline and oil, and other fossil fuel materials (hydrocarbons); nonpoint pollution

Water Pollution Inorganic chemicals – acids, salts, toxic metals; point and nonpoint Toxic chemicals – poisonous chemicals, incl. heavy metals (lead, mercury, cadmium); industrial and household chemicals

Water Pollution Physical agents – heat and suspended solids such as soil Radioactive waste – from power plants or nuclear processing and defense facilities

Wastewater Treatment Plants Pipes lead from residential and industrial areas to wastewater treatment plants for treatment before being returned to lakes and rivers Not 100% effective, especially with industrial wastewater Sludge – product of treatment – can be used as fertilizer or bricks

Primary Sewage Treatment One settling tank

Secondary Sewage Treatment Two settling tanks

Other Treatment Uses

Solutions: Primary and Secondary Sewage Treatment

Solutions: Septic Tank System

Pathogens Disease-causing microorganisms Enter water through untreated wastewater/animal feces Cholera, hepatitis, typhoid E. coli checked using “fecal coliform test”

Bioaccumulation Or biomagnification Build up of toxic pesticides in animals through the food chain

Eutrophication Eutrophication – build-up of abundance of nutrients in lakes and streams over time uses up large amounts of oxygen dissolved in water

Artificial eutrophication Eutrophication caused by humans Normal process which has been accelerated Inorganic plant nutrients (phosphorous and nitrogen) enter water through sewage and fertilizer runoff

Eutrophication Phosphorous – contained in detergents, animal wastes - causes excessive algal growth

Algae Blooms Large mats of algae which float on the water As algae die and decompose, large amts of dissolved oxygen are used Fish suffocate

Water Quality as Measured by Dissolved Oxygen Content in Parts per Million

Dilution and Decay of Degradable, Oxygen-Demanding Wastes in a Stream

Thermal Pollution Excessive amounts of heat added to a body of water From power plants and other industries -use water as a cooling system -hot water returned to stream/river -can cause massive fish kills (suffocate) -hot water does not hold as much dissolved oxygen as cold water

Clean Water Act “to restore and maintain the chemical, physical, and biological integrity of the nation’s waters” To make all surface water clean enough for fishing and swimming

Groundwater Pollution Pesticides, fertilizers, agricultural chemicals that seep into groundwater EPA has detected at least 200 hazardous chemicals that can seep through the soil and into groundwater Porosity vs. Permeability

Principal Sources of Groundwater Contamination in the U.S.

Groundwater Contamination from a Leaking Gasoline Tank

Solutions: Groundwater Pollution, Prevention and Cleanup

Ocean Pollution

Runoff At least 85% of ocean pollution comes from the land River runoff

Dumped directly in the ocean Sludge from wastewater treatment Ships dump directly into ocean

Residential Areas, Factories, and Farms Contribute to Pollution of Coastal Waters

A Large Zone of Oxygen-Depleted Water in the Gulf of Mexico Due to Algal Blooms

Oil Spills Large disasters: ex. Exxon Valdez only about 5% of oil pollution Most oil is from tankers slowly leaking (706 Million Gallons of oil per year!!!) 100 Million in the US Oil spilled when loading and offloading tankers Offshore oil rigs

Plastic Plastic fishing lines - strangulation, trapped animals Clear plastic bags - block digestive systems in turtles Six-pack rings - around necks

The North Pacific Gyre The world’s largest “landfill”: 100 Million tons of floating plastic, stretching for 500 nautical miles!

Prevention MARPOL - International Convention for the Prevention of Pollution From Ships prohibits discharge of oil and plastics in oceans and coastal waters Marine Protection, Research, and Sanctuaries Act - double hulls on tankers

Solutions: Coastal Water Pollution, Prevention and Cleanup

Ocean Ownership Jurisdiction problems Law of the Sea Treaty - 22 km (12 nautical miles) = exclusive economic zone