22-12-2012, 06:49 PM
Recent topics of regulatory systems of current interest.
1Recent topics.ppt (Size: 1.56 MB / Downloads: 29)
Water Resources
Over the last century
Human population has increased 3x
Global water withdrawal has increased 7x
Per capita water withdrawal has increased 4x
About one-sixth of the world’s people don’t have easy access to safe water
Most water resources are owned by governments and are managed as publicly owned resources
Human water needs
A person needs about 1 gallon water/day for hydration
In the US each person uses about 188 gallons/day
An additional 657 gallons/person/day are used for irrigation, industrial use.
Total per capita use is about 2000 gal/person/day
If world’s water supply were 100 liters, the usable supply would be about 0.5 tsp
US has highest per capita water withdrawal, followed by Canada, Australia, Russia, Japan
Groundwater Pollution
>70,000 chemicals are used not; effects of many are not known
Each year another 700-800 new chemicals are produced
55 million tons of hazardous chemical wastes are produced in the US each year
The 20 most abundant compounds in groundwater at industrial waste disposal sites include TCE, benzene, vinyl chloride…all are carcinogens, and also affect liver, brain, and nervous system
Inorganic Pollutants
3 groups
1) Produce no heavlth effects until a threshold concentration is exceeded—e.g., NO3 –ook at , 50mg/liter; at higher levels: methaemoglobinaemia
2) No threshold—e.g.—genotoxic substances: some natural and synthetic organic compounds, microorganic compunds, some pesticides, arsenic
3) Essential to diets: F, I, Se—absence causes problems, but too much also causes problems