Water Quality

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Traditional Aboriginal Knowledge

Water Quality

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Environmental Law
Benefical Uses of Water
Major Elements that make up living tissue
Other important, minor elements
Karst Topography
Residence Time
Water Quality

adapted to HTML from lecture notes of Prof. Stephen A. Nelson Tulane University

Environmental Law

Benefical Uses of Water

Most Elements in food and water come from the soil.

Major Elements that make up living tissue:

From Soil From Atmosphere
Sodium Carbon (from CO2)
Magnesium Oxygen
Potassium Water
Calcium Nitrogen

Other important, minor elements

Karst Topography

Seen in areas underlain by limestone. The limestone is easily dissolved by slightly acid groundwater, and collapses, leaving behind very rugged topography on the surface.
Sinkholes As caverns become larger the roofs become unstable and collapse forming large craters or sinkholes . Because water traveling through the limestone does not pass through sand to clean it, water derived from a limestone aquifer can be easily contaminated by human activity.
A few links relating to Karst topography can be found below:

Ground Subsidence
Due to withdrawal of groundwater is a problem in some areas when the water is taken out of mixed clays and sands the remaining empty pore spaces collapse compacting the soil and making future water retention impossible.

Residence Time

The average time that a substance resides in a reservoir is referred to as the resident time.
For example, each day over an extended period of time, a hotel has:

A steady state - same number leaving as entering.
For groundwater:

Water Quality Concentrations

Usually measured in Parts Per Million, or ppm. (Although can also be expressed as mg/liter)

EPA standards for lead in drinking water specify that it can not be present in concentrations greater than 0.015 ppm or 0.015 mg/Liter.
A number of organic compounds that are carcinogenic have maximum allowed concentrations of 0.005 ppm, or even less. A very small amount of these can effect the gorundwater.
For example:
If your septic tank has a volume of 1,000 gallons you need only place 0.00032 ounces of such an organic compound to raise the concentration level higher than drinking water standards. Some of these materials include benzene (a common ingredient in gasoline) and dry cleaning materials.
Dissolved Substances in Water