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Water

We begin this Chapter with the disturbing statement that world supplies of fresh water are in jeopardy, not only in the U.S., but in China, India and other large economies. Water is becoming the most abused natural resource. The threat to fresh water is of two types:

Quantity

Diminishing quantities from underground aquifers, owing to growing depletion arising from both industrialization and population growth: The 2014 London World Water Summit projected that world water consumption will double between 2014 and 2025.

Widespread contamination and pollution of all water on the planet, only 1.5 percent constitutes fresh water. 97 percent is saltwater in oceans. Water usage is heavily concentrated in agriculture. 93 percent of water consumption occurs in agriculture, mainly for irrigation. (Note: the figures are for water consumed : water that becomes unavailable for other uses).

Of total water consumption, only 7% is for household and industrial use.

Quality

Sanitation challenges affecting water resources continue to mount. To illustrate, contaminated water worldwide is a leading cause of infant mortality from diarrhea and related gastric problems (2 million children a year die). Contaminated water in many areas has led to widespread cancers of the digestive tract.

*Measures the amount of water left over after utilization by the population of each region.
Some worldwide water data potential water availability worldwide (cubic meters)* 2010
North America 17,400
South America 38,300
Europe 4,240
Africa 5,720
Asia 3,920
Australia and Oceania 83,600
Total annual rainfall in millimeters per year
Eastern U.S. 1,000 - 2,000
Western U.S. 250 - 5,000
Amazonian Rain Forest (Brazil, Colombia, Peru) 2,000 - 3,000β
Northern Chile <250
Sahara <250
Indonesia 2,000 - 3,000
S.E. Asia 1,000 - 3,000
South China 1,000 - 2,000
North China 250 - 300

This experience of China is illustrative concerning problems both water of availability and water quality. Water is relatively plentiful in South China; but very scarce in North China (see Table 18-2). And chemical water pollution as we will see is widespread (if we considered also bacterial pollutants, the problems are even worse).

Chinese rivers are disappearing. 1990s, China had 50,000 rivers with catchment areas of over 100 square km or more. Now, the numbers of such rivers is down to 23,000 : 27,000 rivers have disappeared as rivers in 60 years.

Moreover, 80% of the rivers flowing through China are heavily polluted. Even worse, research reported in the November 11, 2011 issue of Science shows that fully 90% of Chinese shallow groundwater is polluted. 37% of this water is so polluted that it cannot even be treated for use as drinking water. The costs to China yearly from water pollution issues are estimated at 2.3% of GDP. And 70% of Chinese get their drinking water from underground.

In many villages in China, water from contaminated rivers or groundwater is the only source of water available. Every year about 190 million Chinese (15% of the population) become ill from bad water. Every year 60,000 Chinese die because of water pollution. This has happened for two main reasons:

  • In China’s very rapid economic growth experience after 1990 environmental issues were decidedly secondary – incentives were to maximize output, even at heavy costs to air and water quality.
  • China does not have laws on groundwater contamination. This is a striking example of the importance of institutions in economic development (see Chapter___).

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
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Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
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SUYASH
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s. Reply
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Ebrahim
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Ebrahim
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s.
Graphene has a hexagonal structure
tahir
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Cied
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Cied
types of nano material
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I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
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Porter
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what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
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Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
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after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
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silver nanoparticles could handle the job?
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I'm interested in Nanotube
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this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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Source:  OpenStax, Economic development for the 21st century. OpenStax CNX. Jun 05, 2015 Download for free at http://legacy.cnx.org/content/col11747/1.12
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