Transcript Water Pollution

Water Pollution
Big Idea

The LARGER the population GROWS the greater
the pollution will FLOW and the negative effects
we’ll KNOW.
http://www.epa.gov/owow/tmdl/overviewfs.html
Point Source Pollution
vs.
Nonpoint Source Pollution
What’s the difference?
Point Source Pollution

comes from a specific
source, like a pipe

factories, industry,
municipal treatment
plants
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can be monitored and
controlled by a permit
system
What is nonpoint source pollution?
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Nonpoint Source
(NPS) Pollution is
pollution associated
with stormwater or
runoff
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NPS pollution cannot
be traced to a direct
discharge point such
as a wastewater
treatment facility
Examples of NPS
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oil & grease from cars
fertilizers
animal waste
grass clippings
septic systems
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sewage & cleaners from
boats
household cleaning
products
litter
Pollutant Transport Mechanisms
•
NPS pollutants build up on land surfaces during dry
weather
 Atmospheric deposition
 Fertilizer applications
 Animal waste
 Automotive exhaust/fluid leaks
•
Pollutants are washed off land surfaces during
precipitation events (stormwater runoff)
•
Stormwater runoff will flow to lakes and streams
Point or Non-Point Source?
Eroding soil from construction sites
 Leachate from landfill
 Overflowing hog lagoon
 Pesticides
 Septic tank leak
 Storm water run-off from city streets

Point or Non-Point Source?
Eroding soil from construction sites
NON-POINT
 Leachate from landfill POINT
 Overflowing hog lagoon
POINT
 Pesticides
NON-POINT
 Septic tank leak
POINT
 Storm water run-off from city streets
NON-POINT
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Pollutant build-up and wash off are affected
by land use.
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Imperviousness increases runoff
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Land use changes impact build up
Linking Land Use to Water Quality
More Imperviousness = More Water
What is impervious cover?
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roads, rooftops, parking lots, and other hard
surfaces that do not allow stormwater to soak
into the ground

“predominant American vegetation”
Impervious Cover
• provides a surface for
accumulation of
pollutants
• leads to increased
polluted runoff and
flooding
• inhibits recharge of
groundwater
Impact of Nonpoint Source Pollution
fish and wildlife
 recreational water
activities
 commercial fishing
 tourism
 drinking water quality

Pollutants Found in Runoff
Sediment
Soil particles
transported from
their source
Biochemical Oxygen Demand (BOD)
● Oxygen depleting material
Leaves
Organic material
Toxics
● Pesticides
 Herbicides
 Fungicides
 Insecticides
● Metals (naturally occurring
in soil, automotive
emissions/ tires)
 Lead
 Zinc
 Mercury
● Petroleum Hydrocarbons
(automotive exhaust and
fuel/oil)
Debris
Litter and illegal dumping
Nutrients
● Various types of materials that
become
dissolved and
suspended in water (commonly
found in fertilizer and plant material):
 Nitrogen (N)
 Phosphorus (P)
Bacteria/ Pathogens
Originating from:
● Pets
● Waterfowl
● Failing septic systems
Thermal Stress
Heated runoff,
removal of
streamside
vegetation
Potential Sources of Pollutants
Found in Residential Areas
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Nutrients: Fertilizers
and septic systems
Pathogens: Pet waste
and septic systems
Sediment:
Construction, road
sand, soil erosion
Toxic: Pesticides,
household products
Debris: Litter and illegal
dumping
Thermal: heated runoff,
removal of streamside
vegetation
Pollutants from Agriculture
Sediment
 Nutrients
 Pathogens
 Pesticides
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Why are these pollutants important?
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Sediment reduces light penetration
in stream, clogs gills of fish and
aquatic invertebrates.
Nutrients act as fertilizer for algae &
aquatic plants which can cause
highly varying dissolved oxygen
levels. At low DO levels, the
aquatic life has the potential to be
harmed.
Toxics can impact life and
contaminate drinking water
supplies.
Bacteria/Pathogens are an indicator
of possible viruses present in the
system.
Inefficient Irrigation
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Worldwide, the
amount of land under
irrigation has been
increasing.
Whether from
aquifers or surface
bodies of water, the
majority of the
freshwater we use for
irrigation is lost
before it ever
reaches the crops.
Figure 14-15
Inefficient Irrigation
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Flood and Furrow Irrigation
Inefficient “flood and
furrow” irrigation, in which
fields are liberally flooded
with water that may
evaporate from shallow
standing pools, accounts
for 90% of irrigation
worldwide.
Over-irrigation leads to
waterlogging and
salinization, which affects
1/5 of farmland today and
reduces world farming
income by $11 billion.
Unfortunately, huge
amounts of groundwater
are being used up for little
gain; because of the dry
climate and inefficient
irrigation methods.
We Can Cut Water Waste in
Irrigation
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Flood irrigation
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Wasteful
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Center pivot, low pressure sprinkler
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Low-energy, precision application
sprinklers
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Drip or trickle irrigation, microirrigation
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Costly; less water waste
Center pivot
(efficiency 80% with low-pressure
sprinkler and 90–95% with LEPA
Drip irrigation
sprinkler)
Gravity flow
Water usually pumped from
(efficiency 90–95%)
(efficiency 60% and 80% with surge valves) Above- or below-ground
underground and sprayed
Water usually comes from an
from mobile boom with
pipes or tubes deliver water
aqueduct system or a nearby river.
sprinklers.
to individual plant roots.
Fig. 13-20, p. 335
Solutions: Reducing Irrigation
Water Waste
Eutrophication
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Most nutrients in water come from organic matter
(leaves, waste, etc.)
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Nutrients are an essential part of any aquatic
ecosystem, but when slow-moving waters contain
too much, they are eutrophic.
Eutrophication
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Eutrophication= build-up of organic matter in
water causing algal blooms
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Outcomes:
• Decreased sunlight
• Decaying matter uses oxygen
• Suffocation/Fish Kills 
Artificial Eutrophication
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Humans act as a catalyst by adding excess
nutrients to the soil
Main culprits= phosphates from fertilizers and
cleaning agents
Human activity can also cause thermal pollution
POLLUTION OF
GROUNDWATER
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It can take hundreds to thousand of years
for contaminated groundwater to cleanse
itself of degradable wastes.
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Nondegradable wastes (toxic lead, arsenic,
flouride) are there permanently.
Slowly degradable wastes (such as DDT)
are there for decades.
Groundwater has low flow rates, few bacteria,
& cold temps - all slow down recovery time
Avg. recycling time for groundwater = 1400
years
Leaking
tank
Water
table
Groundwater
flow
Free gasoline
dissolves in
Gasoline
leakage plumegroundwater
(liquid phase) (dissolved
phase)
Migrating
vapor phase
Contaminant plume movesWater well
with the groundwater
Fig. 21-8, p. 502
Surface water vs. Groundwater
Which is generally more polluted?
~ Surface Water
Which is harder to clean up?
~ Groundwater
Groundwater pollution sticks around...
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Very cold, no bacterial breakdown
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Very slow water movement: recharge can
take 100’s or 1000’s of years
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Pollutants can stick to rocks in aquifer and
pollute new water
What Pollutes Groundwater?
Sources of Groundwater pollution...
landfills
 leaky underground storage tanks
 mines
 septic tanks
 hazardous waste - deep well injection
 any pollutant in runoff that percolates
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Laws
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Clean Water Act – surface water
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1972 – make water swimmable and fishable by
regulating point sources
1977 and 1987 – storm water runoff
Section 404 – requires permit for draining,
dredging, filling wetlands
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Mitigation banking
Safe Drinking Water Act (1974) – monitors
levels of contaminants in groundwater