Earth's Supply of Water
What percentage of water is fresh water?
3%
What is heat capacity?
The ability of a material to absorb heat. It looks at how long the material takes to heat up and cool down.
What are global cooling periods called?
Glacial periods.
Name 3 natural occurrences that affect water supply.
Flood, droughts, and earthquakes.
True or false? The only harmful contaminants in water are physical materials.
False. Contaminants can be:
Biological - both visible and microscopic organisms (such as bacteria and viruses)
Chemical - dissolved substances that come from natural processes (such as dissolving limestone) or human activity (such as dissolved road salts
Physical - all materials that do not dissolve in water (such as animal waste and plant debris)
What is salinity? In terms of water, at what point does the salinity become unsafe and why?
Salinity refers to how much salt is dissolved in water. If the percent is over 1%, it is unsafe because at that point the salt is taking moisture out of our bodies rather than hydrating it.
Why to large bodies of water cause more precipitation in areas around it?
More water vapours/moisture rises into the air, becoming clouds and eventually turning to precipitation.
What are periods of global warming called?
Interglacial periods.
Name and describe a human cause of water table changes that can occur during dry spells in nature.
Overuse of wells. When there is a dry spell in nature, our groundwater supply cannot recharge. For this reason, overuse of wells during this time can deplete underground aquifers, often for long periods.
True or false. Our drinking water goes through a treatment system that isn't monitored too closely, but it usually does its job.
False. Our drinking water does go through a treatment system, but it is monitored and checked often. Our drinking water undergoes many tests and treatments, done by highly trained individuals and scientists that look for and problems in our treatment process, and any microscopic contaminants in water samples.
Where is most of our fresh water?
Most of our fresh water is in the form of ice.
What does it mean when someone says that large bodies of water have a moderating effect on air temperatures?
Large bodies of water affect the climate of nearby regions so that it does not have as much fluctuation/change. Temperatures will only differ a small amount.
How does cold weather effect glaciers and ice sheets?
If cold weather continues and snow builds up, glaciers and ice sheets grow and spread.
Name and describe a human cause of water table changes that involves bottled water.
Water diversion and export. The bottled water industry removes large quantities of water from our water supply. Given that it is removed and not replaced, like it would be in the natural water cycle, it depletes the watershed that it was extracted from.
True or false? Drinking water from a lake, river or reservoir is completely safe if you just boil it before drinking it.
False. Boiling the water will kill harmful organisms, but will not remove chemicals or physical contaminants. For this reason, water goes through different treatments that depends on the conditions of the water source, before being distributed to drink.
What is an aquifer?
An underground freshwater reservoir created by rock and soil layers that allow large amounts of water to collect within them naturally.
What is a microclimate? How does it relate to large bodies of water?
An area with a small, localized climate that differs from the larger climate around it. It relates to large bodies of water because a microclimate is created around them due to their moderating effects.
How does the human production of carbon dioxide and other gases affect ice?
Human production of these gases creates the "greenhouse effect", in which the gases stay in Earth's atmosphere and do not allow heat to leave as it should. This makes for warmer temperatures, which results in receding glaciers and melting ice sheets.
Name and describe a human cause of water table changes that involves issues caused by economic development.
Farming and industry practices. Many large-scale farms and industries need immense quantities of water in their operations. This water is then discharged (released or poured out) directly into a water body, the atmosphere, a wastewater drainage system, or a ground filtration system. When this happens it is often not as clean as it was when taken, or it is a smaller amount that what was taken.
Many developing countries cannot afford to build facilities to treat or test drinking water. How can this be harmful to the individuals living there?
The individuals living in these areas are forced to drink water that is often contaminated and this can make them ill, and even kill them.
Describe the process of the water cycle.
Water evaporates, the water vapour rises into the atmosphere, cools and condenses into clouds. Clouds moisture is released as precipitation. Precipitation in snow form may become part of a glacier or ice sheet, while rain can run into rivers and lakes, or soak into the ground, refilling aquifers. Water that the ground cannot absorb fast enough, or that falls on impermeable surface becomes run-off that eventually flows to a body of water.
How does the moderating effect work?
Given the high heat capacity of water, it takes longer to heat up, and longer to cool down than land and air. This means that when it is very warm in the day, or summer and the land and air are quick to heat up, the air from the water is still cooler, and when it replaces the rising air from the land, it cools it. The opposite happens at night and in the winter, where the land and air are quick to cool, but the water is still warmer, and so the water replaces the cool air with warmer air, not allowing it to get too cold.
How do ice changes (glaciers and ice sheets increasing or shrinking) affect the water system?
When glaciers and ice sheets increase, less water is available in oceans, the atmosphere and other water systems, and it causes lower sea levels. When they shrink, water is released as liquid and gases, adding more fresh water to fresh water bodies, and decreasing the salinity of oceans. Significant shrinking can cause floods.
Describe the issues related to both the falling of water tables, and rising of water tables.
When the level of the water table falls, this means that the watershed has had more water taken from it than put back and there is now a shortage of ground water supply. When the level of the water table rises, this can cause flooding, and can cause drinking water to be contaminated.
What do we do with our groundwater in order to make sure that it is safe to drink?
The water that we get from wells is usually filtered to remove contaminants, and is tested regularly through samples to ensure it is safe to drink.