Chapter 14Water Pollution

Water Pollution

The contamination of streams, rivers, lakes, oceans, or groundwater with substances produced through human activities and that negatively affect organisms.

Point sources- distinct locations that pump waste into a waterway.

Nonpoint sources- diffuse areas such as an entire farming region that pollutes a waterway.

Types of pollutants:

Organic – human and animal wastes

Inorganic – not from living things

Nonchemical pollutants

Human Wastewater

Water produced by human activities such as human sewage from toilets and gray water from bathing and washing clothes or dishes.

Three reasons scientists are concerned about human wastewater:

1. Oxygen-demanding wastes like bacteria that put a large demand for oxygen in the water

2. Nutrients that are released from wastewater decomposition can make the water more fertile causing eutrophication

3. Wastewater can carry a wide variety of disease-causing organisms.

Biochemical Oxygen Demand (BOD)

BOD- the amount of oxygen a quantity of water uses over a period of time at a specific temperature.

Lower BOD values indicate the water is less polluted and higher BOD values indicate it is more polluted by wastewater.

Organic pollution increases BOD due to action of decomposers.

High BOD for decomposers lower O2 levels for other organisms, which can cause dead zones

Example of a dead zone: Gulf of Mexico at the mouth of the Mississippi River

Eutrophication

Eutrophication is an abundance of fertility in a body of water.

Cultural eutrophication is caused by an increase in nutrients, such as fertilizers, especially N and P.

In natural systems, N & P are limiting factors – adding them causes an algal bloom.

Eutrophication can cause a rapid growth of algae which eventually dies, causing the microbes to increase the BOD.

Common Diseases from Human Wastewater

1/6th of the World’s population does not have access to safe drinking water

Cholera*

Typhoid fever

Stomach flu

Diarrhea

Cholera

Hepatitis*

* Major water-borne diseases world-wide

Testing for pathogensCannot look for all possible

pathogens – instead test for an indicator species

Fecal coliform bacteria (E. coli is one type) which live in human and animal intestines

Detecting the presence of these organisms shows that organic waste is in the water

Treatments for Human and Animal Wastewater

Septic (meaning ‘with bacteria’) systems- a large container that receives wastewater from the house.

Bacteria break down the organic material.

Advantage: relies on natural processes – no electricity needed

Disadvantage: tank must be pumped out every 5-10 years

Treatments for Human and Animal Wastewater

Sewage Treatment Plants- centralized plants in areas with large populations that receive wastewater via a network of underground pipes.

Primary treatment – solid waste settles and dries to sludge which is treated and sent to landfill, burned, or converted to fertilizer

Secondary treatment – use bacteria to breakdown organic matter to CO2 and inorganic nutrients. Aeration is used to encourage aerobic bacterial growth (less odor). Remaining water is released to local waterway.

Treatments for Human and Animal Wastewater

Manure lagoons- large, human-made ponds line with rubber to prevent the manure from leaking into the groundwater. After the manure is broken down by bacteria, it is spread onto fields as fertilizers.

Additional contaminantsSubstance Natural

sourcesAnthropogenic

sourcesEffects Removal

Lead

Arsenic

Mercury

Acids

Pesticides

Pharmaceuticals

Hormones

Oil Pollution

Ways to Remediate Oil Pollution

Containment using booms to keep the floating oil from spreading.

Chemicals that help break up the oil, making it disperse before it hits the shoreline.

Bacteria that are genetically engineered to consume oil

No really good plans for:

Underwater plumes

Shoreline oil removal

Other Water Pollutants

Solid waste pollution (garbage) – most goes to landfills, some goes in ocean

Sediment pollution (sand, silt and clay) – some naturally occurring but much now is anthropogenic

Thermal pollution – usually an increase in temp. Can cause thermal shock – warm H2O can hold much less O2. Factories must use cooling towers before putting water back in natural system.

Noise pollution – sonar and other noise can interfere with whale communication.

Water Laws

Clean Water Act- (1972) supports the “protection and propagation of fish, shellfish, and wildlife and recreation in and on the water”.

Issued water quality standards that defined acceptable limits of various pollutants in U.S. waterways.

Does NOT include groundwater

Water Laws

Safe Drinking Water Act- (1974, 1986, 1996) sets the national standards for safe drinking water.

It is responsible for establishing maximum contaminant levels (MCL) for 77 different elements or substances in both surface water and groundwater.

Latest data some good news

In 2004, in the U.S. bodies of water that support their ‘designated uses’ (aesthetics, recreation, protection of fish, source of drinking water)

56% of all streams

35% of lakes & ponds

70% of bays & estuaries