water pollution. big idea the larger the population grows the greater the pollution will flow...
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Point Source Pollution vs. Nonpoint Source Pollution What’s the difference?TRANSCRIPT
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
can be monitored and controlled by a permit system
What is nonpoint source pollution?
Nonpoint Source (NPS) Pollution is pollution associated with stormwater or runoff
NPS pollution cannot be traced to a direct discharge point such as a wastewater treatment facility
Examples of NPS
oil & grease from cars fertilizers animal waste grass clippings septic systems
sewage & cleaners from boats
household cleaning products
litter
Pollutant Transport Mechanisms
• NPS pollutants build up on land surfaces during dry weather
Atmospheric depositionFertilizer applicationsAnimal wasteAutomotive 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 PesticidesNON-POINT Septic tank leak POINT Storm water run-off from city streets
NON-POINT
Pollutant build-up and wash off are affected by land use.
Imperviousness increases runoff
Land use changes impact build up
Linking Land Use to Water Quality
More Imperviousness = More Water
What is impervious cover?
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
SedimentSoil particles transported from their source
Biochemical Oxygen Demand (BOD) ● Oxygen depleting materialLeavesOrganic 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/ PathogensOriginating from:● Pets● Waterfowl● Failing septic systems
Thermal StressHeated runoff, removal of streamside vegetation
Potential Sources of Pollutants Found in Residential Areas
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
Why are these pollutants important? 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 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 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.
Flood and Furrow Irrigation
We Can Cut Water Waste in Irrigation Flood irrigation
Wasteful
Center pivot, low pressure sprinkler
Low-energy, precision application sprinklers
Drip or trickle irrigation, microirrigation Costly; less water waste
Fig. 13-20, p. 335
Center pivot (efficiency 80% with low-pressure sprinkler and 90–95% with LEPA
sprinkler)Drip irrigation (efficiency 90–95%) Water usually pumped from
underground and sprayed from mobile boom with sprinklers.
Gravity flow (efficiency 60% and 80% with surge valves) Above- or below-ground
pipes or tubes deliver water to individual plant roots.
Water usually comes from an aqueduct system or a nearby river.
Solutions: Reducing Irrigation Water Waste
Eutrophication Most nutrients in water come from organic matter
(leaves, waste, etc.)
Nutrients are an essential part of any aquatic ecosystem, but when slow-moving waters contain too much, they are eutrophic.
Eutrophication Eutrophication= build-up of organic matter in
water causing algal blooms
Outcomes:• Decreased sunlight• Decaying matter uses oxygen• Suffocation/Fish Kills
Artificial Eutrophication 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 It can take hundreds to thousand of years
for contaminated groundwater to cleanse itself of degradable wastes. 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
Fig. 21-8, p. 502
Aquifer
Water well
Migrating vapor phase
Contaminant plume moveswith the groundwater
Free gasolinedissolves ingroundwater(dissolved phase)
Groundwaterflow
Watertable
Gasolineleakage plume(liquid phase)
Leakingtank
Bedrock
Surface water vs. Groundwater
Which is generally more polluted?
~ Surface Water
Which is harder to clean up?
~ Groundwater
Groundwater pollution sticks around...
Very cold, no bacterial breakdown
Very slow water movement: recharge can take 100’s or 1000’s of years
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
Laws Clean Water Act – surface water
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 Mitigation banking
Safe Drinking Water Act (1974) – monitors levels of contaminants in groundwater