Unit 5: Water Systems

Question 1

Water solubility

Answer 1

as a polar substance, water separates from non-polar (Fat soluble) substances

Question 2

Water heat capacity

Answer 2

Water has a high heat capacity, meaning it takes a large amount of energy to change it from liquid to solid or solid to liquid

Question 3

Water expansion as a solid

Answer 3

Unlike most molecules, water expands when it becomes a solid (Ice) decreasing it’s density. This is essential as it allows ice to float on the surface of the water.

Question 4

water as a universal solvent

Answer 4

Water can dissolve all types of salts, minerals, etc. Therefore it can easily distibute resources through the environment and our body

Question 5

Available freshwater one earth

Answer 5

3% of earth’s water is freshwater. 99% of that is inaccessible due to it being frozen or underground

Question 6

The hydrologic cycle

Answer 6

moves water between the atmosphere, lithosphere, hydrosphere, and biosphere through precipitation and evapotranspiration

Question 7

Purification of water through the hydrologic cycle

Answer 7

When water evaporates, all of its impurities do not evaporate with it. This ensures that there is a constant supply of fresh water being provided to the biosphere. Plants also contribute to this process as water evaporates out of the stoma in their leaves. This pathways is called transpiration

Question 8

Runoff

Answer 8

Precipitation collected on the surface and through drainage flow into rivers, lakes, wetlands, and ultimately the ocean

Question 9

groundwater

Answer 9

water that has been absorbed into the ground

Question 10

watershed / drainage basin

Answer 10

a geographic area where all surface runoff drains to a common point

Question 11

Recharge zone

Answer 11

the unsaturated, porous rock and soil that groundwater drains into an Aquafer through

Question 11

Aquafers

Answer 11

As water drains into the ground, the dirt rock and sand filter out any impurities and it collects in underwater basins called Aquafers

Question 12

water table

Answer 12

where the underground water basin meets the recharge zone

Question 13

unconfined aquifers

Answer 13

Aquifers that occur in regions where there is good drainage above so that water can freely seep into the ground.

Question 14

confined aquifers

Answer 14

Aquifers that occur in areas where drainage is poor such as clay, where the densly packed material restrict the water seepage

Question 15

effluent stream

Answer 15

if the water table is at a higher elevation than the bottom of the river, water will flow from the ground into the river.

Question 16

influent stream

Answer 16

there is unsaturated space between the river bottom and the water table, water will flow into the ground. An influent stream is not fed by groundwater and will be entirely reliant on surface runoff. If the watershed is stricken by drought, this could mean that the flow in the influent river declines to only a trickle!

Question 17

Salinization

Answer 17

Recall from the hydrologic cycle that minerals dissolved in water will form residues as water vapour is formed. Over periods of sustained crop irrigation, the dissolved minerals form a white powdery (salt) residue on the field, which reduces overall plant productivity and causes soils to become infertile. The result is bare patches on the landscape where vegetation cannot grow.

Question 18

The 3 R’s of water management strats

Answer 18

Retrofit existing water fixtures with low flow tech such as double flush toilets, water saving shower heads etc.

Repair leaking taps and pipes which currently are responsible for 30% of freshwater loss

reduce consumption of water with shorter showers, not running the tap when shaving / brushing teeth, etc.

Question 19

Point source pollution

Answer 19

originates from discharges that are released through pipes and an obvious point of origin. A key feature about point source pollution is that we can measure a change in water quality by comparing conditions before (or “upstream”) and after (or “downstream”) of the pipe. We can easily evaluate and compare these two sites to determine if the discharge is affecting the water body.

Question 20

non-point source pollution

Answer 20

In non-point discharge, we are referring to a large area of landscape within the watershed where multiple human and natural activities contribute to the water pollution observed. For example, a river that flows over a distance of hundreds of kilometers will travel through regions of forest, grasslands, cities and agricultural crops. As it flows, substances will be introduced with runoff, enter the waterway and cumulatively contribute to an overall change in water quality.

Question 21

Sediment pollution (3)

Answer 21

High turbidity in water reduces the penetration of light and reduces rates of photosynthesis.

Siltation smothers or kills the community of organisms living in the sediment layer.

Chemicals adhered to the sediments have the potential to dissolve in water and impact the biotic community (e.g., pesticides that kill plants and insects; fertilizers that stimulate unwanted plant growth).

Question 22

Eutrophication

Answer 22

Eutrophication is pollution by adding plant nutrients. Nitrogen and phosphorus are nutrients required by all biota and first consumed by plants in the food web.

Question 23

Cyanobacteria

Answer 23

Often associated with eutrophication is the proliferation of one specific group of plants called blue green algae, or cyanobacteria. Cyanobacteria are able to fix nitrogen from the atmosphere and in so doing can transform nitrogen gas into ammonia. Any plant that is able to procure its own source of ammonia has the competitive advantage over others in the plant community and it will dominate when phosphorus is available in excess quantities.

Question 24

biochemical oxygen demand (BOD)

Answer 24

an approach used in determining the amount of dissolved oxygen used to assess the health of an aquatic ecosystem. When BOD is high, DO (dissolved oxygen) levels are low and vice versa.

Question 25

How sewage pollution relates to DO and BOD

Answer 25

Bacteria downstream from a sewage dump begin to rapidly decompose the organic material in the sewage leading to an increase in BOD. At the peak of decomposition, there is so little DO in the water that only the most resilient species survive leading to fish kills. Over time the amount of bacteria decrease, and oxygen diffuses back into the water from the atmosphere to normal levels, but there is still a net loss to biodiversity

Question 26

Winter fish kill

Answer 26

Happens in eutriphied waters during winter months. The ice layer on top of the water blocks sunlight which limits oxygen production from photosynthesis as well as limiting the amount of atmospheric oxygen diffusing into the water. Bacteria in the water decompose the organic material in the water and lower the DO content to dangerously low levels.