Water Pollution

R.ArunkumarR.Arunkumar

Types and Sources of Water Pollution

Point sourcesNonpoint sources

Biological oxygen demandWater qualityWater quality

WaterWaterQualityQuality

GoodGood 8-98-9

Do (ppm) at 20˚CDo (ppm) at 20˚C

SlightlySlightlypollutedpolluted

ModeratelyModeratelypollutedpollutedHeavilyHeavily

pollutedpollutedGravelyGravelypollutedpolluted

6.7-86.7-8

4.5-6.74.5-6.7

Below 4.5Below 4.5

Below 4Below 4 Pg. 535

Point and Nonpoint SourcesNONPOINT SOURCES

Urban streets

Suburban development

Wastewater treatment plant

Rural homes

Cropland

Factory

Animal feedlot

POINT SOURCES

Water pollution

Bacteria,Viruses,Protozoa, Parasitic worms

Oxygen demanding substances Inorganic plant nutrients Organic chemicals Sediment or suspended matter Thermal pollution Genetic pollution

Rainbow smelt1.04 ppm

Zooplankton0.123 ppm

Phytoplankton0.0025 ppm

Water0.000002 ppm

Herring gull124 ppm

Lake trout4.83 ppm

Herring gull eggs124 ppm

Biological Magnification

Pollution of Streams Oxygen sag curveOxygen sag curve

Fig. 20-5

Pollution of Lakes

Eutrophication Discharge of untreated

municipal sewage(nitrates and phosphates)

Nitrogen compoundsproduced by cars

and factories

Discharge of treatedmunicipal sewage

(primary and secondarytreatment:

nitrates and phosphates)

Discharge of detergents

( phosphates)

Natural runoff(nitrates andphosphates

Manure runoffFrom feedlots(nitrates andPhosphates,

ammonia)

Dissolving of nitrogen oxides

(from internal combustionengines and furnaces)

Runoff and erosion(from from cultivation,mining, construction,

and poor land use)

Runoff from streets,lawns, and construction

lots (nitrates andphosphates)

Lake ecosystemnutrient overload

and breakdown of chemical cycling

Fig .22.7, p. 499

Solutions to better water quality

Drainage Area Management Plans Agriculture plots 1987 Water Quality Act

Fig. 20-12

Aquifer

Water well

Migrating vapor phase

Contaminant plume moveswith the groundwater

Free gasolinedissolves ingroundwater(dissolved phase)

Groundwaterflow

Watertable

Gasolineleakage plume(liquid phase)

Leakingtank

Bedrock

Groundwater Pollution: Causes

Coal strip mine runoff

Pumping well

Waste lagoon

Accidental spills

Groundwater flow

Confined aquifer

Discharge

Leakage from faulty casing

Hazardous waste injection wellPesticides

Gasoline station

Buried gasoline and solvent tank

Sewer

Cesspool septic tank

De-icing road salt

Unconfined freshwater aquifer

Confined freshwater aquifer

Water pumping well Landfill

Fig. 20-11

Groundwater Pollution Prevention

Monitoring aquifers

Strictly regulating hazardous waste disposal

Storing hazardous materials above ground

Fig. 21-10, p. 505

Healthy zoneClear, oxygen-richwaters promote growthof plankton and sea grasses,and support fish.

Oxygen-depleted zoneSedimentation and algaeovergrowth reduce sunlight,kill beneficial sea grasses, useup oxygen, and degrade habitat.

Red tidesExcess nitrogen causesexplosive growth of toxicmicroscopic algae,poisoning fish andmarine mammals.

FarmsRunoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.

Toxic sedimentsChemicals and toxic metals contaminate shellfish beds, kill spawning fish, andaccumulate in the tissues of bottom feeders.

Construction sitesSediments are washed intowaterways, choking fish and plants, clouding waters, and blocking sunlight.

Urban sprawlBacteria and viruses fromsewers and septic tanks contaminate shellfish beds

Oxygen-depletedzone

Closedbeach

CitiesToxic metals and oil from streets and parking lots pollute waters;

IndustryNitrogen oxidesfrom autos andsmokestacks,toxic chemicals,and heavy metals in effluents flow into bays and estuaries.

Closedshellfish beds

Fig. 20-15

Reducing Water Pollution through Sewage Treatment

Primary and Secondary sewage treatment.Figure 20-19Figure 20-19

Technological Approach: Using Wetlands to Treat Sewage

((

((

45 centimeterlayer of limestonegravel coated with

decomposing bacteriaFirst concrete pool Second concrete pool

SewageSewage

Wetland typeWetland typeplantsplants

Wetland typeWetland typeplantsplants

TreatedTreatedwaterwater

Global Outlook: Stream Pollution in Developing Countries

Water in many of central China's rivers are greenish black from uncontrolled pollution by thousands of factories.

Figure 20-7Figure 20-7

Case Study: India’s Ganges River: Religion, Poverty, and Health

Religious beliefs, cultural traditions, poverty, and a large population interact to cause severe pollution of the Ganges River in India. Very little of the sewage is treated. Hindu believe in cremating the dead to free the

soul and throwing the ashes in the holy Ganges. Some are too poor to afford the wood to fully

cremate. Decomposing bodies promote disease and depletes

DO.

Case Study: India’s Ganges River: Religion, Poverty, and Health

Daily, more than 1 million Hindus in India bathe, drink from, or carry out religious ceremonies in the highly polluted Ganges River.

Is Bottled Water the Answer? Some bottled water is not as pure as tap

water and costs much more. 1.4 million metric tons of plastic bottles

are thrown away. Fossil fuels are used to make plastic

bottles. The oil used to produce plastic bottles in the

U.S. each year would fuel 100,000 cars.

What Can You Do?

Water Pollution

• Fertilize garden and yard plants with manure or compost instead of commercial inorganic fertilizer.

• Minimize your use of pesticides.

• Do not apply fertilizer or pesticides near a body of water.

• Grow or buy organic foods.

• Do not drink bottled water unless tests show that your tap water is contaminated. Merely refill and reuse plastic bottles with tap water.

• Compost your food wastes.

• Do not use water fresheners in toilets.

• Do not flush unwanted medicines down the toilet.

• Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground.