Unit 5: Water Systems Flashcards
Water solubility
as a polar substance, water separates from non-polar (Fat soluble) substances
Water heat capacity
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
Water expansion as a solid
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.
water as a universal solvent
Water can dissolve all types of salts, minerals, etc. Therefore it can easily distibute resources through the environment and our body
Available freshwater one earth
3% of earth’s water is freshwater. 99% of that is inaccessible due to it being frozen or underground
The hydrologic cycle
moves water between the atmosphere, lithosphere, hydrosphere, and biosphere through precipitation and evapotranspiration
Purification of water through the hydrologic cycle
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
Runoff
Precipitation collected on the surface and through drainage flow into rivers, lakes, wetlands, and ultimately the ocean
groundwater
water that has been absorbed into the ground
watershed / drainage basin
a geographic area where all surface runoff drains to a common point
Recharge zone
the unsaturated, porous rock and soil that groundwater drains into an Aquafer through
Aquafers
As water drains into the ground, the dirt rock and sand filter out any impurities and it collects in underwater basins called Aquafers
water table
where the underground water basin meets the recharge zone
unconfined aquifers
Aquifers that occur in regions where there is good drainage above so that water can freely seep into the ground.
confined aquifers
Aquifers that occur in areas where drainage is poor such as clay, where the densly packed material restrict the water seepage
effluent stream
if the water table is at a higher elevation than the bottom of the river, water will flow from the ground into the river.
influent stream
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!
Salinization
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.
The 3 R’s of water management strats
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.
Point source pollution
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.
non-point source pollution
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.
Sediment pollution (3)
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).
Eutrophication
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.
Cyanobacteria
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.
biochemical oxygen demand (BOD)
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.
How sewage pollution relates to DO and BOD
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
Winter fish kill
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.
