chapter 15 Flashcards
Problems associated with the Colorado River (Past &Present)
-people in Las Vegas are drilling for underground water, even though it threatens the area’s ecology
Tributary
a smaller river slowing into a larger one
Oxbow
an extreme bend in a river
Oxbow lake
the bend is cut off and remains as an isolated, U-shaped body of water
Floodplain
areas nearest to the river’s course that are flooded periodically
Frequent deposition of silt makes floodplain soils
Riparian
riverside areas that are productive and species-rich
Freshwater systems (amount, where it is located, etc.)
- relatively pure, with dissolved salts
- only 2.5% of earth’s water is fresh
- most freshwater is tied up in glaciers and ice caps
Wetlands
Systems that combine elements of freshwater and dry land
Freshwater marshes
shallow water allows plants to grow about the water’s surface
swamps
shallow water that occurs in forested areas
can be created by beavers
Bogs
ponds covered in thick floating mats of vegetation
a stage in aquatic succession
Why wetlands are valuable
slow runoff
- reduce flooding, recharge aquifers filter pollutants
- people have drained wetlands, mostly for agriculture
- southern canada and the US have lost more than half of their wetlands
Littoral zone
region ringing the edge of a water body
Benthic zone
extends along the bottom of the water body
home to many invertebrates
Limnetic zone
open portions of lake or pond where the sunlight penetrates the shallow waters
Profundal zone
water that sunlight does not reach
supports fewer animals because there is less oxygen
Oligotrophic lakes and ponds
have low nutrient and high oxygen conditions
Eutrophic lakes and ponds
have high nutrient and low oxygen conditions
Inland seas
large lakes that hold so much water, their biota is adapted to open water
Groundwater
any precipation that does not evaporate flow into waterways, or get taken up by organism
makes up one fifth of the earth’s freshwater supply
Aquifers
porous sponge-like formations of rock, sand, or gravel that hold groundwater
Zone of aeration
pore spaces are partially filled with water
Zone of saturation
spaces are completely filled with water
Water table
boundary between two zones
Aquifer recharge zone
any area where water infiltrates Earth’s surface and reaches aquifers
Confined/artesian aquifers
water-bearing, porous rocks are trapped between layers of less permeable substrate
-is under a lot of pressure
Unconfined aquifer
- no upper layer to confine it
- readily recharged by surface water
- Groundwater becomes surface water through springs or human-drilled wells
- Ground water may be ancient: the average age is 1,400 years
Consumptive use
water is removed from an aquifer or surface water body, and is not returned
Non-consumptive use
does not remove or only temporarily removes, water from an aquifer or surface water
Dam
- any obstruction place in a river or stream to block the flow of water so water can be stored in a reservoir
- to precent floods, provide drinking water, allow irrigation, and generate electricity
Benefits & drawbacks of dams (Three Gorges Dam Example)
Benefits for three Gorges Dam
Provides flood control, passage for boats, and electricity
Removal
is flooding cities and homes
drowning famland and habitat
pollutants will be trapped
Removal (why & controversies surrounding them) Benefits Power generation Flood control shipping drinking water
Drawbacks
Habitat alteration
population displacement
Sediment capture
water mining
withdrawing water faster than it can be replenished
Dikes & levees
Long raised mounds of earth along the banks of rivers holding rising water in channels
levees can make floods worse by forcing water to stay in channels and overflow
Aral Sea - Past & Present
location => to the right of the caspian, between Kazakhstan and Uzbekistan
irrigation efficiency
only 45% of water is absorbed by crops via “flood and furrow” irrigation
-overirrigation leands to waterlogging, salinization, and lost farming income
Sinkholes
areas were ground gives way unexpectedly
some cities are slowly sinking
Desalinization
removal of salt from seawater or other water of marginal quality
Distilling vs. reverse osmosis
distilling
hastens evaporation and condenses the vapor
reverse osmosis
forces water through membranes to filter out salts
Pathogens/waterborne disease
enters water supply via inadequately treated human waste and animal waste via feedlots
causes more human health problems than any other type of water pollution
Toxic chemicals
from natural and synthetic sources
pesticides, petroleum products, synthetic chemicals
arsenic, lead, mercury, acid rain, acid drainage from mines
effects include: poisoning animals and plants, altering aquatic ecosystems, and affecting human health
Sediment pollution
sediments can impair aquatic ecosystems
clear-cutting, mining, poor cultivation practices
dramatically changes aquatic habitats, and fish may not survive
Solutions: better management of farms and forests; avoid large-scale disturbance of vegetation
Thermal pollution
water water holds less oxygen
dissolved oxygen decreases as temperature increases
water that is too cold can kill aquatic organisms
point source water pollution
discrete locations of pollution
factory or sewer pipes
Nonpoint sources water pollution
pollution from multiple cumulative inputs over a large area
farms, cities, streets, neighborhoods
U.S Clean Water Act
addressed point sources
targeted industrial discharge
Do Nonpoint or point sources have a greater impact on quality?
nonpoint sources have a greater impact on quality
Biological indicators
presence of fecal coliform bacteria and other disease-causing organisms
Chemical indicators
pH, nutrient concentration, taste, odor, hardness, dissolved oxygen
Physical indicators:
turbidity, color, temperature
Sources of Groundwater pollution
natural aluminum, fluoride, sulfates pollution from human causes wastes leach through soils pathogens enter through improperly designed wells Hazardous wastes pumped into ground
Agricultural pollution
nitrates from fertilizers
pesticides dected in more than half of shallow aquifers tested
Wastewater
water that has been used by people in some way
sewage, showers, sinks, manufacturing, storm water runoff
Septic systems
the most popular method of wastewater disposal in rural areas
underground septic tanks separate solids and oils from wastewater
water drains into a drain field decompose the water
solid waste needs to be periodically pumped and landfilled
Primary treatment
physical removal of contaminants in settling tanks (clarifers)
Secondary treatment
water is stirred and aerated so aerobic bacteria degrade organic pollutants
water treated with chlorine is piped into rivers or ocean
Clean Water Act
illegal to discharge pollution without a permit
standards for industrial wastewater
funded sewage treatment plants
