Study Aid 15 - Test 4 - Groundwater Contamination
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School
Virginia Tech *
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Course
2104
Subject
Geography
Date
Dec 6, 2023
Type
Pages
6
Uploaded by BrigadierSteel12120
Hole: GEOS 2104 Study Aid
O-1
Groundwater Contamination
Groundwater Contamination
what process from previous lectures is the biggest cause
of natural groundwater “contamination”?
what does
TDS
measure?
what does
hardness
measure?
how do we keep chemical wastes out of groundwater?
list ways that humans contaminate groundwater:
waste disposal:
(list & explain at least 5 sources of
contamination)
Hole: GEOS 2104 Study Aid
O-2
Groundwater Contamination
accidental spills:
(list at least 4 sources)
intentional “spills”:
(list at least 5 sources)
changing flow of dirty water:
(list at least 2 sources)
Hole: GEOS 2104 Study Aid
O-3
Groundwater Contamination
what is
aqueous-phase
contaminant transport?
(seems trivial, but
non
-aqueous-phase is next…)
what is
advection
?
what is a
contaminant plume
?
what causes it?
what does
hydrodynamic dispersion
do to the plume?
what is
chemical diffusion
?
what is
mechanical dispersion
?
what does geologic heterogeneity do to the plume?
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Hole: GEOS 2104 Study Aid
O-4
Groundwater Contamination
explain how Earth materials can naturally retard (slow
down) or stop contaminant plumes
aquitard
what is
adsorption
?
what common geologic material is good at retarding
contaminant plumes?
what is
non-aqueous-phase
contaminant transport?
define
LNAPL
:
what sorts of chemicals?
where does it flow?
compare to groundwater flow
define
DNAPL
:
what sorts of chemicals?
where does it flow?
compare to groundwater flow
Hole: GEOS 2104 Study Aid
O-5
Groundwater Contamination
how is groundwater contamination discovered?
Answer: chemical testing of groundwater
how is further pollution stopped if a source cannot be
eliminated?
Answer: capture the contaminant near the source
- divert incoming water
- create impermeable barrier around the source
- drain the water out and treat it
how is spreading of the pollution reduced/minimized?
Answer: capture the entire contaminant plume
- create an impermeable barrier around it
- create a cone of depression, drawing
contaminant towards the pumping well
list two ways in which groundwater contamination is
removed from the ground:
Answer:
1) pump out and treat the contaminated water
2) excavate (dig up) the contaminated soil and treat it
what is the disadvantage of each of these techniques?
1) contaminant adsorbed to minerals is left behind
did you remove all the dirty water?
2) expensive and destructive
Hole: GEOS 2104 Study Aid
O-6
Groundwater Contamination
how can groundwater contamination be treated beneath
the surface?
Answer: chemical or biological remediation
- pump in chemicals or bacteria, and let it react
with the contaminant
what is the disadvantage of these techniques?
A: did you fix all the dirty water?
what is the US legal requirement for storage of nuclear
waste?
A: no leakage for 10,000 years
how does it compare with the physics of radioactive
decay?
A: radioactive half-lives 100’s of millions
of years
how does it compare with the reality of finding a safe
place?
A: all places investigated have leaked
where are we storing our nuclear waste?
Answer:
military:
A: salt mine in New Mexico
civilian:
A: at every nuclear power plant (>100)
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