Water Pollution

WATER POLLUTION: SOURCES, TYPES, AND EFFECTS  Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses. Point source: specific location (drain pipes, ditches, sewer lines). Point source: specific location (drain pipes, ditches, sewer lines). Nonpoint source: cannot be traced to a single site of discharge (#1:agricultural / #2: industrial / #3: residential runoff) Nonpoint source: cannot be traced to a single site of discharge (#1:agricultural / #2: industrial / #3: residential runoff)

Effects of Pollutants  Water Pollutants can: Cause disease (Biological Pollutants) Cause disease (Biological Pollutants) Deplete oxygen needed by aquatic organism, (Animal Waste) Deplete oxygen needed by aquatic organism, (Animal Waste) Cause excessive algae growth (Plant Nutrients) Cause excessive algae growth (Plant Nutrients) Add toxins to aquatic systems (Chemical Pollution) Add toxins to aquatic systems (Chemical Pollution) Disrupt photosynthesis (Sediments) Disrupt photosynthesis (Sediments)

POLLUTION OF FRESHWATER STREAMS AND LAKES  Most developed countries have sharply reduced point-source pollution but toxic chemicals and pollution from nonpoint sources are still a problem.  Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.

Global Outlook: Stream Pollution in Developing Countries  Water in many of central China's rivers are greenish black from uncontrolled pollution by thousands of factories. Figure 21-5

Case Study: India’s Ganges River: Religion, Poverty, and Health  Religious beliefs, cultural traditions, poverty, and a large population interact to cause severe pollution of the Ganges River in India. Very little of the sewage is treated. Very little of the sewage is treated. Hindu believe in cremating the dead to free the soul and throwing the ashes in the holy Ganges. Hindu believe in cremating the dead to free the soul and throwing the ashes in the holy Ganges. Some are too poor to afford the wood to fully cremate.Some are too poor to afford the wood to fully cremate. Decomposing bodies promote disease and depletes DO.Decomposing bodies promote disease and depletes DO.

Case Study: India’s Ganges River: Religion, Poverty, and Health  Daily, more than 1 million Hindus in India bathe, drink from, or carry out religious ceremonies in the highly polluted Ganges River. Figure 21-6

POLLUTION OF FRESHWATER STREAMS  Flowing streams can recover from a moderate level of degradable water pollutants if they are not overloaded and their flows are not reduced. The amount of oxygen required by organisms is known as Biological oxygen demand.(BOD) The amount of oxygen required by organisms is known as Biological oxygen demand.(BOD) In a flowing stream, the breakdown of degradable wastes by bacteria depletes DO and creates and oxygen sag curve. In a flowing stream, the breakdown of degradable wastes by bacteria depletes DO and creates and oxygen sag curve. This reduces or eliminates populations of organisms with high oxygen requirements.This reduces or eliminates populations of organisms with high oxygen requirements.

Water Pollution Problems in Streams  Dilution and decay of degradable, oxygen- demanding wastes and heat in a stream. Figure 21-4

POLLUTION OF FRESHWATER LAKES  Dilution of pollutants in lakes is less effective than in most streams because most lake water is not mixed well and has little flow. Lakes and reservoirs are often stratified and undergo little mixing. Lakes and reservoirs are often stratified and undergo little mixing. Low flow makes them susceptible to runoff. Low flow makes them susceptible to runoff.

Cultural Eutrophication  Cultural eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) to a lake. 85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication. 85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.

OCEAN POLLUTION  Oceans, if they are not overloaded, can disperse and break down large quantities of degradable pollutants.

OCEAN POLLUTION  Pollution of coastal waters near heavily populated areas is a serious problem. About 40% of the world’s population lives near on or near the coast. About 40% of the world’s population lives near on or near the coast. The EPA has classified 4 of 5 estuaries as threatened or impaired. The EPA has classified 4 of 5 estuaries as threatened or impaired.  Oceans are impacted by: Sewage Dumping Sewage Dumping Agricultural Runnoff Agricultural Runnoff Garbage Dumping Garbage Dumping Toxic Waste Toxic Waste Oil Oil

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OCEAN POLLUTION  Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff. Figure 21-11

Oxygen Depletion in the Northern Gulf of Mexico  A large zone of oxygen- depleted water forms for half of the year in the Gulf of Mexico as a result of HAB. Figure 21-A

OCEAN OIL POLLUTION  While Oil Spills have devastating effects, most ocean oil pollution comes from human activities on land. Studies have shown it takes about 3 years for many forms of marine life to recover from large amounts of crude oil (oil directly from ground). Recovery from exposure to refined oil (fuel oil, gasoline, etc…) can take years for marine life to recover.

POLLUTION OF GROUNDWATER  Groundwater can become contaminated with a variety of chemicals because it cannot effectively cleanse itself and dilute and disperse pollutants.  It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes. Nondegradable wastes (toxic lead, arsenic, flouride) are there permanently. Nondegradable wastes (toxic lead, arsenic, flouride) are there permanently.

POLLUTION OF GROUNDWATER  Leaky landfills, waste lagoons, and underground storage tanks can introduce contaminants into aquifers According the the EPA, one or more organic chemicals contaminate about 45% of municipal groundwater supplies. According the the EPA, one or more organic chemicals contaminate about 45% of municipal groundwater supplies.

 Most groundwater contamination occurs in shallow unconfined aquifers located near a contaminant source

Groundwater Pollution  Groundwater pollution may go un-noticed for a long time because ground water moves so slowly.  The cloud of contaminated ground water that moves away from the source is called a contaminant plume.

Fig. 21-8, p. 502 Aquifer Water well Migrating vapor phase Contaminant plume moves with the groundwater Free gasoline dissolves in groundwater (dissolved phase) Groundwater flow Water table Gasoline leakage plume (liquid phase) Leaking tank Bedrock

El Toro Marine Base: California

Raytheon Chemical Plant St. Petersburg Florida

PREVENTING AND REDUCING WATER POLLUTION  The key to reducing pollution is to prevent it from reaching bodies of water. Farmers can reduce runoff by planting buffers and locating feedlots away from steeply sloped land, flood zones, and surface water. Farmers can reduce runoff by planting buffers and locating feedlots away from steeply sloped land, flood zones, and surface water. Use substitute chemicals Use substitute chemicals Monitor Landfills and underground tanks Monitor Landfills and underground tanks Store harmful chemicals above ground Store harmful chemicals above ground

PREVENTING AND REDUCING WATER POLLUTION  Most developed countries use laws to set water pollution standards, but such laws rarely exist in developing countries. The U.S. Clean Water Act sets standards fro allowed levels of key water pollutants and requires polluters to get permits. The U.S. Clean Water Act sets standards fro allowed levels of key water pollutants and requires polluters to get permits. EPA is experimenting with a discharge trading policy similar to that for air pollution control. EPA is experimenting with a discharge trading policy similar to that for air pollution control.