Environmental Microbiology of Aquatic and Waste Systems

12 1 Nature, Properties, and Distribution of Water

The science which studies waters on earth is hydrology.
The branch of hydrology which studies the oceans is
oceanography; the branch of hydrology which studies
inland waters running or standing, fresh or saline, is
limnology (from the Greek: limne = lake, logos = study).
Limnology includes the study of (natural and man-
made) lakes and ponds, rivers and streams, wetlands,
and groundwaters.
The water which man requires for his domestic and
industrial purposes, however, is freshwater, which
forms only a small proportion by volume of the earth’s
waters (Fig. 1.5 and Table 1.3). Although the abundant
waters of the oceans and seas can be de-salinated to
provide freshwater, the present methods of doing so
are uneconomical.
Freshwater is thus a relatively scarce commodity.
For this reason, it is purified and reused in some

countries. Water which has been used and rain water

draining into the ground, all enter, and form part of,

the hydrologic cycle.

References

Anonymous (2009a). Water structure and science. http://www.

btinternet.com/~martin.chaplin/index.html. Accessed 10

Sept 2009.

Anonymous (2009b). Table of density of pure and tap water and

specific gravity. SIMertic.co.uk. http://www.simetric.co.uk/

si_water.htm. Accessed on 12 June 2009.

Anonymous (2009c). Area and depth of the seas and oceans of

the world. http://www.infoplease.com. Accessed 6 Dec 2009.

Anonymous (2009d). Seas and oceans. http://www.infoplease.

com/ipa/A0001773.html. Accessed 10 Dec 2009.

Anonymous (2010a). The top ten longest rivers of the world.

http://www.infoplease.com/toptens/worldrivers.html.

Accessed 9 Dec 2009.

Table 1.6 The top ten largest lakes of the world (From http://www.infoplease.com/toptens/largelakes.html; Anonymous 2010b.
With permission)

Lake Location Volume (km^3 ) Area (km^2 ) Salinity
Caspian Sea Azerbaijan, Iran, Kazakhstan,
Russian Federation, Turkmenistan

78,200 km^3 374,000 Mostly saline

Baikal (Ozero Baykal) Russian Federation 23,600 km^3 31,500 Fresh
Tanganyika Burundi, Congo (Democratic Republic),
Tanzania, Zambia

19,000 km^3 32,900 Mostly fresh

Superior Canada, United States of America 12,100 km^3 82,100 Fresh
Malawi (Nyasa, Niassa) Malawi, Mozambique, Tanzania 7,775 km^3 – Fresh
Michigan United States of America 4,920 km^3 57,750 Fresh
Huron Canada, United States of America 3,540 km^3 59,500 Fresh
Victoria Kenya, Tanzania, Uganda 2,760 km^3 68,460 Fresh
Great Bear Lake Canada 2,292 km^3 31,326 Fresh
Great Slave Canada 2,088 km^3 29,568 Fresh

Table 1.5 The top ten longest rivers of the world (From http://www.infoplease.com/toptens/worldrivers.html; Anonymous 2010a.
With permission)

S/No Name Length (km) Location Destination
1 Nile 6,690 Egypt Mediterranean Sea
2 Amazon 6,570 Amapa-Para, Brazil Atlantic Ocean
3 Mississippi-Missouri 6,020 Louisiana, USA Gulf of Mexico
4 Yangtze 5,980 Kiangsu, China East China Sea
5 Yenisey 5,870 Russia Yenisey Gulf in Kara Sea
6 Amur 5,780 China Tatar Strait
7 Ob-Irtysh 5,410 Russia Gulf of Ob in Kara Sea
8 Plata-Parana 4,880 Argentina-Uruguay Atlantic Ocean
9 Yellow (Hwang) 4,840 Shantung, China Yellow Sea
10 Congo (Zaire) 4,630 Angola-Zaire Atlantic Ocean