Exam 3 Flashcards
Point Source
pipes, ditches, and sewage outfalls
Nonpoint sources
runoff from agricultural fields, lawns, forestry, and parking lots
Atmospheric deposition and gaseous pollutants that dissolve in water
HARDEST TO CONTROL
Living Organisms as a Pollutant
- pathogens and fecal coliform
- contributes to 26 mil deaths/yr
- highest in urban areas from untreated human sewage, animal waste in fields, and meat packing factories sending waste into water
Types of toxins and how they’re pollutants
heavy metals - remain in ecosystems for long periods of time and are from industry and fossil fuels
Inorganic acids - acids in streams are a byproduct of industrial processes and mining, acid rain is from combustion of ffs
Salt - sources are from road salt, toxic in high doses, and can change salinity in ecosystems
toxics organics - pesticides, herbicides, cleaning agents
Bioaccumulation
ingested and metabolize, stored in fatty tissues
Biomagnification
more concentrated in successive tropic levels of food web
Sediment as a pollutant
80% of water degradation comes from erosion
Erosion…
- smothers bottom dwellers
- decreases water clarity
- may have nutrients/toxins attached
Thermal pollution
decreases DO, loss of riparian vegetation, harmful to cold-blooded organisms
Plastic pollution
microplastics are found in humans and fish, plastic fragments can absorb toxic chemicals and harbor dangerous microbes
What does the oxygen sag curve tell us?
Tells the direction of the flow of dissolved oxygen. Right after the DO hits the decomposition zone, it decreases. Gets higher when there is more flow in the recovery zone. (8 ppm for fish and 2 ppm for microorganisms)
Biological Oxygen Demand
the amount of oxygen consumed in five days by microorganisms in the water
How have humans altered the N cycle? Gulf of Mexico?
we’ve added more nitrogen, so algal blooms are caused more frequently in coastal ecosystems
Clean Water Act
restore and maintain chemical, physical, and biological integrity of the nation’s water
all water should be swimmable and fishable
set limits on discharge by industries and municipalities
Groundwater
water that lies beneath the ground surface, filling the pore space between soil particles, sedimentary rock layers, and cracks/crevices
Vadose zone
all material between the earth’s surface and zone of saturation
Water table
upper boundary of the zone of saturation
Capillary fringe
layer of variable thickness that directly overlies the water table (takes up water through capillary action)
aquifer
a body of saturated rock or sediment through which water can move easily
Unconfined aquifer
a partially filled aquifer exposed to the land surface and marked by a rising and falling water table
confined aquifer
an aquifer completely filled with pressurized water and separated from the land surface by a relatively impermeable continuing bed, such as shale
How do unconfined aquifers recharge?
water tables rise in wet seasons and fall in dry seasons as water drains out of the saturated zones into rivers
Gaining stream
a stream that receives water from the zone of saturation
Losing stream
a stream that loses water to the zone of saturation
What factors control the movement of groundwater?
clay content
friction
surface tension
shape, size, orientation of grains
hydraulic gradient
Which direction does groundwater flow?
higher elevation to lower elevation
areas of lower use to higher use
wet areas to dry areas
How do properties of soil influence groundwater?
porosity (fraction of void space in rock or soil) determines if water will move through fast
permeability - measure of earths materials to transmit fluid
hydraulic conductivity - ability of material to let water move through it
Order (from highest to lowest) the types of soils flow rates.
coarse sand and gravel –> coarse fine –> fine silt and clay
Darcy’s Law
rate of flow is proportional to the hydraulic gradient and determined by the permeability of the medium
Q = -KA * dh/dl
Explain the components (with units) of Darcy’s Law.
Q - discharge (m^3/s)
K - hydraulic conductivity (m/s)
A - area (m^2)
dh/dl = hydraulic gradient (slope = rise/run)
What is a well?
a deep hole, generally cylindrical, that is dug or drilled into the ground to penetrate an aquifer within the saturated zone
Hydraulic head
measure of energy potential, driving force of groundwater flow
Hydraulic head in confined aquifer
hydraulic head is above confined aquifer and there is substantial pressure energy
Hydraulic head in unconfined aquifer
head is equal to water table elevation at any location
Cone of Depression
depression of the water table formed around a well when water is pumped out
Drawdown
lowering of water table near a pumped well
What happens when withdrawal > recharge?
Regional water table drops
Why does the water table drop when withdrawal > recharge?
ground surface settles because water no longer supports rock and sediment
Why do wells need to be deeper, what are the costs?
because the groundwater goes deeper
costs include:
- needing more electricity to pump water to the surface
- sinkholes can form
How can groundwater become contaminated by salt water in regions of extreme groundwater withdrawal?
groundwater pumping can change groundwater flow patterns and cause saltwater to be drawn into freshwater zones
Relationship between urbanization and decline in groundwater
more impervious surfaces, so less water seeps into the ground to recharge groundwater
Kaushal et al
- chloride concentrations made up up to 25% of the concentration of waters in streams in Maryland NY in winter
- up to 100x more in unimpacted forests in summer
- mean annual chloride concentration increased as a function of impervious surfaces
Weitjers et al
-altered catchment land use has a major effect on freshwater biodiversity and the rate of species loss
- on average, every 10% of natural land use lost leads to a loss of almost 6% of native freshwater fish and macroinvertebrates
Ledford & Lautz
- chloride concentrations in connected streams had less temporal variation because of groundwater discharge acting as a buffer
- In summer, there was no nitrate in disconnected because of high primary productivity and lack of resources BUT it was higher in connected streams because of high vegetation riparian zones
