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