Issue 17
February 21, 2002
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What is the difference between a sea and a lake? Looking at the names of many sea and many lakes does not readily demonstrate an identifiable difference. There are salt water lakes and fresh water seas and some lakes that are bigger than other seas. Bruce Schoenegge, Irvine, California, USA
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![Salt crust resulting from receding lake, Lake Frome, Australia.](https://bac-lac.wayback.archive-it.org/web/20061210025953im_/http://www.ec.gc.ca/EnviroZine/images/issue17/aerial_Lake_Frome_Australia.jpg) Salt crust resulting from receding lake, Lake Frome, Australia.
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In order to understand why some smaller salt water bodies are called lakes and others seas it is necessary to realize that lakes are, in geological time scales, transitory in naturethey form, mature and die.
Some water bodies that started out as saltwater seas over time became closed-off from the oceans. Depending on the quantity of fresh water flowing in from rivers, glacial melt water, or other sources, the salinity could have declined to the point where the water became relatively fresh. The Sea of Aral is probably an example of where this transition has occurred. Similarly the reverse can occur whereby freshwater lakes can become open to the sea so that the salinity increases, as in the Baltic Sea. The Black Sea is an example that has alternated between fresh and salt water conditions over geological time. Evidence for these changes can be found in ancient fossils of organisms some of which were known to be tolerant of saltwater while others were known to have been intolerant.
No doubt there was also some confusion in the naming of water bodies by the early explorers based on their first impressions and certainly one can understand why some may have been inappropriately named. In addition the subsequent translation of the names between different languages could also have added to the confusion.
Here are some definitions of water bodies:
- Ocean
- The whole body of salt water that covers nearly 3/4 of the surface area of the globe. In particular, each of the main areas into which the sea is divided geographically, e.g. Atlantic, Pacific. Oceans are tidal, living systems containing a multitude of biological organisms.
- Average depth of the world's oceans: 3,962 metres(13,000ft)
- Maximum depth: 10,680 meters; (35,040ft)
- Average salt content - 3.5% (mostly common salt, NaCl but with some magnesium and calcium salts)
- Average density - 1.026
- Sea
- The expanse of salt water that covers most of the earth's surface and surrounds the land masses. A body of salt water that is secondary in size to oceans.
- Lake
- A large area of water surrounded by land. Normally fresh water but in some cases can be appreciably saline depending on the geology of the underlying and surrounding terrain. Lakes are living systems containing various quantities of biological organisms. Lakes can be classified according to the level of bioproductivity as oligotrophic (low productivity), mesotrophic or eutrophic (high productivity). The productivity is usually controlled by the amount of nutrients (mostly phosphorus and nitrogen) present in the water and the amount of light that can penetrate the water column.
- River
- A large natural stream of water flowing in a channel to the sea, a lake or another such river. The flow can be permanent of seasonal.
- Stream
- A small, narrow river flowing on the surface of, or beneath, the ground.
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Related Web Sites:
National Water Research Institute
Freshwater
Marine Debris in Canada
Aral Sea
Black Sea Environmental Internet Node
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Issue Number and Date |
Question |
Issue 70 November 16, 2006 |
Is there a difference between a species being threatened, at risk or endangered, or can these terms be used interchangeably? |
Issue 69 October 12, 2006 |
Does the weather affect the Northern Lights? Where and when is it best to view them? |
Issue 68 September 14, 2006 |
Can I plant a tree in fall? How do I prepare the young trees in my yard for winter? |
Issue 67 August 10, 2006 |
What costs more, driving on the highway with the air conditioning on or with the windows down? |
Issue 66 June 15, 2006 |
Who should I talk to about an Asian Long-horned Beetle I found? |
Issue 65 May 19, 2006 |
I found an injured bird in my backyard. Is there someone I can call to get help for the bird? |
Issue 64 April 12, 2006 |
When does the Greater Snow Goose hunting season begin? |
Issue 63 March 22, 2006 |
What is an Earthquake? |
Issue 62 February 16, 2006 |
How do I find out about recycling in my city? |
Issue 61 January 19, 2006 |
What is the sunrise and sunset time today? |
Issue 60 December 15, 2005 |
What do I need to export protected species and their products from Canada? |
Issue 59 November 17, 2005 |
How do I obtain historical weather data? |
Issue 58 October 13, 2005 |
How do you calculate oxygen production of a tree? |
Issue 57 September 15, 2005 |
What is probability of precipitation (POP)? |
Issue 56 August 11, 2005 |
How many tonnes of greenhouse gases are created by a forest fire per hectare? |
Issue 55 June 9, 2005 |
Do you have any CO2 emissions data of a Suzuki Aerio SX 2003 Fastback, manual transmission? |
Issue 54 May 13, 2005 |
What produces more carbon dioxide: driving a 13-year-old van or the manufacturing of a new vehicle?
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Issue 53 April 14, 2005 |
Does a campfire create as much pollution as a fireplace? |
Issue 52 March 10, 2005 |
Where can I find information on water usage? |
Issue 51 February 10, 2005 |
Are there any subsidies or rebates for a household that installs solar panels? |
Issue 50 January 13, 2005 |
Why was the tsunami in Southeast Asia so devastating? Is there anything I can do to help? |
Issue 49 December 9, 2004 |
How can polar ice melting increase the world's sea level? |
Issue 48 November 15, 2004 |
How do various light bulbs compare for energy efficiency? |
Issue 47 October 18, 2004 |
Where can I find information on carbon neutral conferencing? |
Issue 46 September 10, 2004 |
Why should people recycle? |
Issue 45 August 5, 2004 |
What are the environmental benefits to using cloth versus disposable diapers? What types of cloth diapers are available? |
Issue 44 June 3, 2004 |
What are the main causes of air pollution? |
Issue 43 May 7, 2004 |
How did the Zebra Mussel originally get into Lake Erie and why did they populate so quickly? |
Issue 42 April 16, 2004 |
What causes a tornado to form, how long does the average tornado last and how is it tracked? |
Issue 41 March 11, 2004 |
What causes the temperature to drop as the sun rises, commonly known as "sunrise sag"? Are there any environmental or scientific benefits to snow? |
Issue 40 February 12, 2004 |
When the temperature is extremely cold is it better to idle the car to warm the engine before driving or warm the engine by driving? |
Issue 39 January 15, 2004 |
Will climate change have an effect on storm systems such as thunderstorms, tornadoes, blizzards and hurricanes? |
Issue 38 December 4, 2003 |
Why are the salt trucks going out before the snow falls? |
Issue 37 November 13, 2003 |
Are electric solar panels an efficient and cost saving alternative for household use? |
Issue 36 October 9, 2003 |
How do pollutants enter our drinking water from a landfill site? |
Issue 35 September 11, 2003 |
Are there incentive programs in Canada to take older vehicles off the road? |
Issue 34 July 24, 2003 |
In the last 10 years, what natural disasters has Canada faced and at what cost? |
Issue 33 June 26, 2003 |
Are fluorescent bulbs that contain mercury more harmful to the environment and human health than incandescent bulbs? |
Issue 32 May 22, 2003 |
Is diesel fuel more or less polluting than regular gasoline? Do motorcycles and scooters emit more toxins than other combustion engine vehicles? |
Issue 31 April 24, 2003 |
I would like some information on lawn care products. |
Issue 30 March 20, 2003 |
What are future concerns about landfills? |
Issue 29 February 20, 2003 |
Which areas of Canada have the greatest number of species at risk? |
Issue 28 January 23, 2003 |
Is it true that using salt on roadways to prevent icing in the winter is bad for the environment? Are there alternatives? |
Issue 27 December 19, 2002 |
How much do I save in greenhouse gas emissions by not having a car? |
Issue 26 November 21, 2002 |
What does the recycling symbol stand for and what do the numbers inside the triangle represent? |
Issue 25 October 17, 2002 |
How do I buy good quality compact fluorescent light bulbs? Does turning them on and off every time one leaves the room shorten the life of the bulb? |
Issue 24 September 19, 2002 |
Why doesn't Canada get any hurricanes? What climate is associated with hurricanes? |
Issue 23 August 15, 2002 |
What guidelines or regulations does Canada have in place for the use of two-stroke engines? Will they be restricted for marine use? |
Issue 22 July 18, 2002 |
What are the major causes of water pollution and what is being done to prevent them? |
Issue 21 June 21, 2002 |
Is pressure-treated wood a good choice for fencing? What are the alternatives? Are the alternatives worth the fuss? |
Issue 20 May 21, 2002 |
What can be used to seal or paint a pressure-treated wooden play structure to make it safe? |
Issue 19 April 22, 2002 |
How does a rooftop garden improve air quality? How much air can a rooftop garden clean? |
Issue 18 March 21, 2002 |
What is a wetland and what good is a wetland? |
Issue 17 February 21, 2002 |
What is the difference between a sea and a lake? There are salt water lakes and fresh water seas and some lakes that are bigger than other seas. |
Issue 16 January 31, 2002 |
What do you do with old computers and the parts that are obsolete or just a few years old but lack the latest capabilities? |
Issue 15 December 19, 2001 |
Are plans available for building your own compost bin?
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Issue 14 November 30, 2001 |
How much does wearing a hat or tuque in the winter help prevent body heat loss? |
Issue 13 October 30, 2001 |
What are endangered species and how do they obtain their designation? |
Issue 12 August 27, 2001 |
Why not ban the sale of lead sinkers, jigs and shotshell altogether? |
Issue 11 July 25, 2001 |
How do hydroelectric plants affect the environment? |
Issue 10 June 27, 2001 |
Where would I be able to find an overview of the air, water and soil quality in different regions of Canada? |
Issue 09 June 4, 2001 |
Could you give me a historical picture of the air quality in Ontario, and include information on what is being done to clean up the air? |
Issue 08 May 18, 2001 |
Do you have any information on the effects of weather on human behaviour? |
Issue 07 May 1, 2001 |
How long does a cotton t-shirt take to decompose in a landfill? |
Issue 06 April 2, 2001 |
What is the procedure for cleaning up oil spills? |
Issue 05 March 19, 2001 |
Where do I get general info on landfills? How many are there in Canada? |
Issue 04 February 15, 2001 |
Does composting create greenhouse gases? How to calculate relative humidity. |
Issue 04 February 15, 2001 |
Can relative humidity be calculated if you have the Barometric pressure, elevation, temperature and dew point? |
Issue 03 January 29, 2001 |
What happens to confiscated endangered species products? |
Issue 03 January 29, 2001 |
What to do with your old appliances? |
Issue 02 January 15, 2001 |
How many trees does it take to convert the carbon dioxide produced by a car travelling 20 000 kilometers per year to oxygen? |
Issue 02 January 15, 2001 |
Which plants are the most efficient at converting carbon dioxide to oxygen? |
Issue 02 January 15, 2001 |
Do coniferous trees continue to convert carbon dioxide to oxygen or are they simply inactive during the winter months? |
Issue 02 January 15, 2001 |
What is an Alberta Clipper and how did it get its name? |
Issue 01 December 18, 2000 |
How much fresh water does Canada have? |
Issue 01 December 18, 2000 |
How much carbon dioxide does a litre of gasoline produce? |
Issue 01 December 18, 2000 |
What is climate and how is it different from weather? |
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