Environmental Sciences: Towards a Sustainable Future Chapter 17. Water: Pollution and Prevention. Introduction:. Mississippi watershed. Mississippi River. The Mississippi river and its tributaries encompass 40% of the US land mass. Eventually delivers water to the Gulf of Mexico.
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Water: Pollution and Prevention
The Mississippi river and its tributaries encompass 40% of the US land mass.
Eventually delivers water to the Gulf of Mexico.
As tributaries travel through agricultural land they carry fertilizer runoff to the Mississippi then to the Gulf.
Nitrogen carried to the marine waters causes eutrophication.
Eutrophication causes an area of depleted oxygen (dead zone)
This was noticed by biologists in 1974 who thought it to be similar to the occurrence at Chesapeake Bay which has seasonal hypoxia (depleted oxygen/dead zone) but later became aware of the connection between nitrogen and the hypoxia.
With the dead zone expanding, the Gulf fishing industry was eventually affected.
$2.8 billion enterprise
Gained national attention and eventually congress passed the Harmful Algal Bloom and Hypoxia Research and Control Act.
Since 1960 the number of dead zones has doubled every decade.
Worldwide, over 200 dead zones are now known according to the UN environment program.
Involves discharge of substances from factories, sewage systems, power plants, underground coal mines and oil wells.
Relatively easy to identify.
Easier to regulate.
Scattered over broad areas such as runoff, storm water drainage, atmospheric deposition.
Harder to identify source
Harder to regulate
Good health is primarily a result of prevention of disease through public-health measures.
To cut in half the amount of people living without sustainable access to safe drinking water and basic sanitation by the year 2015.
The amount of oxygen that water can hold in solution is very limited.
In cold water dissolved oxygen can reach 10 ppm and even less in warm water.
Pollutants are concentrated as they pass up the food chain
Nitrogen and phosphorus
Fresh water affected more by phosphorus
Salt water affected more by nitrogen
Many of these nutrients are found in water only because of human activity.
National pollution discharge elimination system
Addresses point sources and issues permits that regulate discharges from waste water treatment plants and industrial sources.
Total maximum daily load
Evaluates all sources of pollutants entering a body of water, espaecially non-point sources, according to the water’s ability to assimilate the pollutant.
Lesson 17.2 17Wastewater management and treatment
Oxygen is added to the secondary-treatment system through an air-bubbling system. A mixture of debris eating organisms (activated sludge) is added to the water and is vigorously aerated. Organisms reduce the biomass of the organic materials.
Biological Nutrient Removal
A secondary activated-sludge system added to remove nutrients and oxidize detritus. (added because of cultural-eutrophication).
Because this water is actually purer than the body of water that it enters, it will dilute the pollutants in the body of water, improving the quality.
Used to treat sewage sludge.
Raw sludge mixed with wood chips or some other water absorbing material. It is then placed in long rows (windrows)that allow air to circulate. A machine turns the material, bacteria and other decomposers break it down turning it into an excellent humus-like material.
Lesson 17.3 17Eutrophication
What kind of plants would dominate in
oligotrophic and eutrophic conditions?