Chapter 20 - Water Pollution

Water pollution

is the introduction of chemical, physical, or biological agents into water that degrades the quality of the water and affects the organisms that depend on it

Point source pollution

is discharged from a single source (ex. wastewater treatment plant, oil tanker)

Nonpoint source pollution

comes from many sources (ex. farm runoff, storm sewers)

Water-Soluble Inorganic Chemicals

• Acids, salts, toxic metals & chemicals

• Endocrine Disruptors lead to birth defects, developmental disorders & gender imbalances

• Organic Chemicals - Oil, gasoline, plastics, pesticides, detergents

Organic Chemicals

Oil, gasoline, plastics, pesticides, detergents

Oxygen-Demanding Wastes

(organic wastes that are decomposed aerobically)

• Measured by the Biological Oxygen Demand (BOD), which is the amount of oxygen needed for decomposition

• An Oxygen Sag Curve is a plot of dissolved oxygen levels versus the distance from a source of pollution, usually excess nutrients and biological refuse.

• Oceanic Dead Zones are areas of low oxygen caused by increased nutrient pollution

hypoxic

such low oxygen levels that aquatic life starts to die

anoxic

no dissolved oxygen, no life

Inorganic Plant Nutrients

Nitrates, Phosphates

Pathogens

(disease-causing agents)

Bacteria, viruses, protozoa, parasitic worms

Endocrine Disruptors

Chemicals that can lead to birth defects, developmental disorders and gender imbalances

Sediment

(suspended material)

Measured by turbidity

Heavy Metals

Harm through bioaccumulation

Thermal Pollution

(thermal shock)

Lowers DO and organisms immune response

Streams and Rivers have the ability

to rapidly recover from pollution events because of their continuous **flow** and dilution resulting from surface runoff. Problems occur when the influx of pollutants is large (ex. hog pit break) or the stream flow is reduced (ex. dams, sedimentation)

Livestock sewage is of great concern in North Carolina estuaries

leading to degraded ecosystems and the immergence of *Pfiesteria piscicida*.  *Pfeisteria* is a toxic dinoflagellete that thrives in the high nutrient loads commonly originating from livestock, and is responsible for immense fish kills in NC waters.

Lakes and reservoirs

are particularly vulnerable to pollution because they often contain stratified layers that undergo little mixing.  This may result in accumulation of pollutants and significant reductions in dissolved oxygen.

eutrophication

Lakes receive inputs of nutrients and silt from the surrounding land.  This natural nutrient enrichment is called ___.

 Cultural ___

is the accelerated input of nutrients by human activity.

The Law of the Sea Treaty (1982)

• 134 nations participated

• laws of a coastal nation extend 22 km from its coastline (territorial sea)

• nations control of economic activity, environmental preservation and research extend 370 km from its coastline (economic zone)

85% of all ocean pollution originates from

land activities, with coastal areas taking the most damage.  This is not surprising because half the world’s population lives within 160 miles of the coast.

Oil pollution

in the seas results primarily from land runoff.

However, the most preventable sources may be oil rigs and oil tankers. Oil may be cleaned up by the use of

o Floating booms that contain the spill

o Skimmers that vacuum up the oil

o Absorbent pads

o Coagulation agents that cause the oil to clump

o Dispersing agents that break up the slick

Until 2010, the largest offshore oil spill in U.S. history occurred in 1989

the *Exxon Valdez* tanker ran aground in Prince William Sound, Alaska.  The spill of almost 11 million gallons affected the Alaskan coastline equivalent of New York City to Miami.

On April 20, 2010

BP’s Deepwater Horizon oil rig sank of the coast of Louisiana after an explosion.  The aftermath left broken wellheads one mile deep that leaked for 107 days.  The total numbers make it the largest offshore oil spill in U.S. history.

• 206 million gallons of oil

• 1.84 million gallons of dispersant (Corexit 9500)

Groundwater contamination is of particular concern

groundwater flows very slowly, limiting dilution and dispersion.  Therefore, it can take tens to thousands of years for groundwater to cleanse itself.

In rural and suburban areas

sewage from each house is discharged into a septic tank, which is emptied every 3 – 5 years.

In urban areas

wastes travel to wastewater treatment plants through a network of sewer pipes.

Primary sewage treatment

is a mechanical process that uses screens to filter out debris.

Secondary sewage treatment

is a biological process in which aerobic bacteria are used to remove up to 90% of biodegradable, oxygen-demanding organic wastes.

Advanced sewage treatment

is a series of specialized chemical processes that remove specific pollutants left in the water after primary and secondary treatment. 

**Groundwater Protection Method 1**

Pumping polluted groundwater to the surface to clean and return is not economically feasible.  Therefore, prevention of groundwater pollution is the only effective way of protecting the resource.

**Groundwater Protection Method 2**

Monitoring aquifers near landfills and underground tanks

**Groundwater Protection Method 3**

Requiring leak detection systems for underground tanks

**Groundwater Protection Method 4**

Banning disposal of hazardous wastes in deep injection wells and landfills

**Groundwater Protection Method 5**

Storing hazardous liquids above ground

The Clean Water Act of 1972 was based on the Water Pollution Control Act of 1948. 

These laws and subsequent amendments set standards for allowed levels of key water pollutants and requires polluters to get permits limiting how much of various pollutants they can discharge into aquatic systems.

Methods for Sustainable Water Use 1

Source reduction to reduce the toxicity or volume of pollutants

Methods for Sustainable Water Use 2

Reuse of wastewater

Methods for Sustainable Water Use 3

Recycling pollutants