` area iv: pollution iva3: water pollution. ` 22-1 types, effects, sources of water pollution l...

Area IV: Pollution

IVA3: Water Pollution

22-1 Types, Effects, Sources of Water Pollution

water is polluted by infectious bacteria, inorganic and organic chemicals, and excess heat

water pollution: any chemical, biological, or physical change in water quality that has a harmful effect on living organisms

the WHO estimates that 3.4 million people/yr people die prematurely from waterborne diseases

an estimated 1.5 million people/yr in U.S. become ill from infectious agents


scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms

number of colonies of fecal coliform bacteria present in a water sample

drinking water: 0 colonies/100 mL swimming water: < 200 colonies/100 mL

bacterial source tracking (BST) biological oxygen demand (BOD): the

amount of dissolved oxygen consumed by aquatic decomposers

Fig. 22-2 Fecal coliform bacteria


scientists monitor water quality, cont. chemical analysis: inorganic and organic

chemicals present, sediment content, and turbidity of water

indicator species genetic techniques are being used to develop

organisms that will glow in the presence of specific pollutants such as toxic heavy metals in the ocean and carcinogens in food

Fig. 22-3 Water quality and dissolved oxygen


water pollution can come from a single source or variety of dispersed sources

point sources discharge at specific locations examples: drainpipes, sewer lines easy to identify, monitor, and regulate

non-point sources are scattered and diffuse and can’t be traced to any single site of discharge

examples: runoff from croplands, livestock feedlots

difficult and expensive to identify and control these discharges

Fig. 22-4 Point and nonpoint sources


sources of water pollution, cont. leading sources: agriculture, industries, mining

agricultural activities: erosion overgrazing fertilizers pesticides excess salt from irrigated soils


too much rain and too little rain can increase water pollution

increased moisture with more intense rains can flush harmful chemicals, plant nutrients, and microorganisms into waterways

prolonged drought can reduce river flows so there is less dilution available

warmer water contains less dissolved oxygen

22-2 Pollution of Freshwater Streams streams can recover from moderate levels

of degradable water pollutants if the flows are not reduced

dilution and biodegradation can allow recovery of stream pollution if:

they are not overloaded do not have reduced flow due to damming,

agricultural diversion, or drought

22-2 Pollution of Freshwater Streams stream recovery, cont.

breakdown of pollutants by bacteria creates an oxygen sag curve

organisms with a high oxygen demand can’t survive in the curve

factors in size of curve: volume of the stream volume of wastes entering flow rate temperature pH levels

Fig. 22-5 Dilution and decay of wastes

22-2 Pollution of Freshwater Streams most developed countries have reduced

point source pollution, but toxic chemicals and pollution from non-point sources are still problems

the U.S. has avoided increases in pollution from point sources in most streams

cleanup of rivers: Cuyahoga River in Ohio and the Thames River in Great Britain

there are sometimes large fish kills, and contamination of drinking water from industry, mining, and non-point runoff of fertilizers and pesticides

22-2 Pollution of Freshwater Streams stream pollution in most developing

countries is a serious and growing problem half of the world’s 500 major rivers are heavily

polluted many run through developing countries where

waste treatment is minimal or nonexistent

22-2 Pollution of Freshwater Streams the Ganges River in India is severally

polluted ~350 million people live in the Ganges River

basin with little treatment of sewage Hindu beliefs compound problem

air pollution from cremated bodies water pollution from bodies thrown in river

government solutions: waste treatment plants in the 29 large cities

along the Ganges electric crematoriums on its banks introduction of snapping turtles as body

scavengers

22-3 Pollution of Freshwater Lakes lakes are less effective at diluting pollutants

that enter them often stratified with little vertical mixing very little flow occurring may take from 1–100 years to flush and

change water in lakes and reservoirs much more vulnerable to runoff contamination

of all kinds of materials chemical concentrations build up as they pass

through the food webs in lakes

Fig. 22-6 Biomagnification of PCBs

22-3 Pollution of Freshwater Lakes human activities can reduce dissolved

oxygen and kill some aquatic species natural eutrophication: nutrient enrichment of

lakes from runoff depends on composition of the surrounding

drainage basin can enrich abundance of desirable

organisms cultural eutrophication occurs due to runoff

usually near urban or agricultural areas and in coastal water, enclosed estuaries, and bays

can lead to serious pollution problems

Oligotrophic lake

Eutrophic lake

Fig. 22-7 Cultural eutrophication

22-3 Pollution of Freshwater Lakes human activities, cont.

cultural eutrophication, cont. the EPA states that 85% of large lakes near

major population centers in U.S. have some amount of cultural eutrophication

can be reduced or prevented by: banning or limiting phosphates in

detergents advanced treatment methods to remove

nitrates and phosphates from wastewater use of soil conservation to reduce runoff

22-3 Pollution of Freshwater Lakes human activities, cont.

hot weather or drought -> “blooms” of organisms -> reduction in lake productivity

reduced sunlight + decomposition -> increase in bacteria populations -> decrease in DO -> fish kills -> anaerobic bacteria take over

cleanup of lakes includes removing excess weeds, controlling plant growth, and pumping air through lakes and reservoirs to avoid oxygen depletion

pollution prevention is cheaper than cleanup

22-3 Pollution of Freshwater Lakes Case Study in lake recovery: Lake

Washington, Seattle sewage diverted from the lake to Puget Sound,

where rapid water exchange dilutes sewage recovery took 4 years lake had not filled with weeds and sediment concern about Puget Sound due to increased

urban runoff and growing population What is the best way to deal with pollution?

Lake Washington

22-3 Pollution of Freshwater Lakes Case Study: pollution of the Great Lakes

has dropped but is still a problem the Great Lakes contain about 95% of the

fresh surface water in the United States, and 20% of the world’s fresh surface water

> 38 million people obtain drinking water from the lakes

vulnerable due to less than 1% outflow to the St. Lawrence River but lots of inputs

Lake Erie: shallowest; was the most polluted; high concentration of people and industry

Fig. 22-8 Great Lakes basin

Western Lake Eerie

22-3 Pollution of Freshwater Lakes Case Study: Great Lakes pollution, cont.

since 1972, the U.S. and Canada have worked together to reduce pollution

there is still a large area of depleted oxygen that occurs in the center of the lake each August for unknown reasons

a 2000 survey by the EPA stated that more than ¾ of the shoreline is not clean enough for swimming or use as drinking water

non-point land runoff is now a greater problem than industrial pollution

22-3 Pollution of Freshwater Lakes Case Study: Great Lakes pollution, cont.

biomagnification of the depositions from atmospheric contaminants means that one fish in four is unsafe for human consumption

EPA funding for cleanup has also dropped by 80% since 1992

environmentalists call for banning the use of bleach, building new incinerators, and stopping the discharge into the lakes of 70 toxic chemicals

22-4 Pollution of Groundwater groundwater is vulnerable to pollution

spilling gasoline, oil, paint thinners, etc. onto the ground can contaminate groundwater

low-risk ecological problem high-risk health problem contaminated water in the aquifer will slowly

flow, creating a plume of contaminated water contaminants in groundwater are not diluted or

dispersed because this water moves usually less than 0.3 meter per day

22-4 Pollution of Groundwater groundwater vulnerability, cont.

cleansing is slow; factors: lower oxygen content colder temperature of the water smaller populations of decomposing

bacteria it can take hundreds of years to cleanse

degradable wastes; nondegradable wastes are there permanently

22-4 Pollution of Groundwater the extent of groundwater contamination is

generally unknown EPA and U.S. Geological Survey figures state

that one or more organic chemicals contaminate about 45% of municipal groundwater supplies in the U.S.

~26,000 industrial waste ponds and lagoons in U.S. do not have a liner to prevent seepage

many underground storage tanks have leaks determining the extent of a leak is costly, and

the cost of cleanup is more costly yet

Fig. 22-9 Groundwater contamination

22-4 Pollution of Groundwater groundwater contamination, cont.

nitrates can contaminate groundwater, esp. in agricultural areas; form nitrites in the body

arsenic is released into drinking water when a well is drilled into arsenic-rich soils and rock

WHO estimates that more than 112 million people drink water containing 5–100 times the recommended level of 10 parts/billion

Bangladesh has a serious problem with arsenic, but the UN and several NGOs have begun to assess wells and tag them

22-4 Pollution of Groundwater prevention is the most effective and

affordable way to protect groundwater from pollutants

underground tanks in the U.S. and some other developed countries are now strictly regulated

old, leaky tanks are being removed, and the surrounding soils are being treated

Fig. 22-10 Groundwater pollution

22-5 Ocean Pollution oceans can disperse and break down large

quantities of degradable pollutants if they are not overloaded

raw sewage, sludge, oil, and some degradable industrial wastes can be degraded, especially in deep-water areas

some marine animals have been less affected by pollutants than expected

there is controversy as to whether this is a viable solution to the problem

22-5 Ocean Pollution pollution near heavily populated areas

~40% of the world’s population lives on or within 62 miles of the coast

in most coastal developing countries and some developed countries, sewage is dumped into the sea without treatment

human viruses (not removed by waste treatment) have been found in coastal waters

nutrient enrichment from nitrate and phosphate runoffs causes algal blooms, killing fish and fish-eating birds

Fig. 22-11 Pollution of coastal waters

22-5 Ocean Pollution pollution near populated areas, cont.

extensive non-point runoffs have caused seasonal, large oxygen-depleted zones in temperate coastal waters

the second largest of these zones forms each summer at the mouth of the Mississippi River in the Gulf of Mexico

scientists are investigating whether fine clay particles can pull algae out of the water

preventive measures: restore wetlands, reduce nitrogen inputs, sewage treatment

Fig. 22-

22-5 Ocean Pollution pollutants from six states contaminate the

shallow Chesapeake Bay estuary a huge drainage basin adds both point and

non-point pollutants to the waters point sources: 60% of phosphates nonpoint sources: 60% of nitrates

the bay is shallow, so only 1% of the waste that enters is flushed into the Atlantic Ocean

commercial harvest of oysters, crabs, and fish has fallen sharply since 1960 because of overfishing, pollution, and disease

Fig. 22-13 Chesapeake Bay

22-5 Ocean Pollution Chesapeake Bay estuary, cont.

in 1983, the U.S. started an integrated coastal management plan

reduction of runoff upgrading waste treatment plants better monitoring of industrial discharges banning phosphates from detergents

between 1985 and 2000, 27% decline in phosphorus levels, 16% drop in nitrogen levels, recovery of grasses on bottom of bay

reduction in funding has slowed progress

Fig. 22-14 Coastal water pollution

22-5 Ocean Pollution Chesapeake Bay estuary, cont.

introduction of disease-resistant oysters could greatly reduce water pollution because oysters filter algae and silt from water

oysters recycled the entire volume of the bay in 3–4 days

over-harvesting and two parasitic oyster diseases reduced the oyster population

several ways to reintroduce oysters into the bay are being considered

22-5 Ocean Pollution oceans as dump sites

dumping industrial wastes off U.S. coasts has stopped, dumping of dredge spoils continues

many countries dump sewage sludge (banned in U.S. since 1992)

50 countries with >80% of world’s merchant fleet agreed not to dump ship waste at sea

the London Dumping Convention of 1972: 100 countries agreed not to dump highly toxic pollutants, high-level radioactive wastes in open sea

22-5 Ocean Pollution oil pollution

crude petroleum and refined petroleum reach the ocean from a number of sources

day-to-day activities such as leaks from pipelines and storage tanks, tankers being washed out, loading and unloading

studies show that most ocean oil pollution comes from human activities on land

22-5 Ocean Pollution oil pollution, cont.

harmful ecological and economic effects, but most disappear within 3–15 years

volatile organic hydrocarbons kill some aquatic organisms, especially larval forms

oil on birds and mammals causes drowning or fatal loss of body heat

bottom-dwelling organisms are killed when heavy components sink to the sea floor

recovery: 3 years from crude oil, 10-15 years from refined oil products

oil slicks on shore bad for local economy


only about 15% of the oil spilled can be recovered with current techniques

mechanical methods include floating booms, skimmers, and absorbent devices

chemical methods use coagulating agents for clumping oil and dispersing agents to break up slicks; fire to burn off floating oil

biological methods utilize bacteria that are able to degrade oil; probably best method


relevant laws the Oil Pollution Act of 1990 set up a trust

fund of $1 million per spill for cleanup by 2015, all oil tankers operating in U.S.

waters must be double hulled preventing or reducing pollution from the

land and from streams is the key ocean pollution control must be linked with

land-use and air pollution policies to be effective

22-6 Preventing Surface Water Pollution reduce non-point pollution by preventing it

from reaching bodies of surface water agricultural non-point pollution can be reduced

by: reducing soil erosion reducing fertilizer use; slow-release fertilizer reforestation of watersheds keeping cover crops on farmland planting buffer zones between farmland and

surface water nearby relying more on bio controls than pesticides

EPA required to require 15,500 of the largest feedlots to apply for EPA permits

22-6 Preventing Surface Water Pollution most developing countries do not have

laws to set water pollution standards most cities in developing countries discharge

80–90% of untreated sewage water used for drinking, bathing, and washing clothes

in U.S., the Clean Water Act sets standards for allowed levels of key water pollutants and requires polluters to obtain permits to discharge pollutants into aquatic systems

EPA is experimenting with a discharge trading policy using credits

22-6 Preventing Surface Water Pollution septic tanks and sewage treatment can

reduce point-source water pollution ~1/4 of homes in U.S. served by septic tanks most urban areas served by sewage treatment

plants some 1,200 cities have combined storm runoff

and sewer lines because it is cheaper; can overflow

sewer systems in the U.S. are estimated to cost $10 billion a year for 10 years to install, expand, and repair the aging sewer network

Fig. 22-15 Septic tank system

22-6 Preventing Surface Water Pollution septic tanks and sewage treatment, cont.

raw sewage generally undergoes one or two levels of treatment

primary sewage treatment removes grit, floating objects, and suspended solids

removes ~60% of suspended solids and 30–40% of organic wastes

secondary sewage treatment is a biological process where aerobic bacteria remove up to 90% of O2-demanding organic wastes

tertiary sewage treatment: removing specific pollutants

Fig. 22-16 Primary and secondary treatment


raw sewage treatment, cont. a combination of primary and secondary

treatment removes 95–97% of the suspended solids and

oxygen-demanding organic wastes 70% of most toxic metal compounds 70% of P, 50% of N, 5% of dissolved

salts most U.S. cities have combined plants 34 East Coast cities screen out floating

objects and discharge sewage into coastal waters


water is bleached to remove colors and then disinfected (usually chlorination) to kill disease-causing bacteria and some viruses

ozonation and use of ultraviolet light are increasing as methods of disinfection

22-6 Preventing Surface Water Pollution sewage sludge

sludge is a thick, gooey mixture of bacteria, solids, chemicals, and metals when industrial and household wastes are combined

some sludge undergoes anaerobic digestion to decompose organics and produce compost

~36% of these biosolids are used as fertilizer; rest is added to landfills or incinerated

removing infectious bacteria, toxins, and metals is expensive, seldom done in the U.S.

health problems?

Fig. 22-17 Problems with sludge

22-6 Preventing Surface Water Pollution preventing toxic chemicals from reaching

treatment plants would eliminate these from sludge and water that is discharged

require industries and businesses to remove toxic and hazardous wastes from water sent to sewage treatment plants

encourage reduction or elimination of toxic chemical use and waste

have households switch to waterless composting toilet systems maintained by professionals

22-6 Preventing Surface Water Pollution wetlands can be used to treat sewage

low-tech, low-cost alternative to expensive waste treatment plants

sewage -> sedimentation tanks -> oxidation ponds -> (1 month) artificial marsh

genetic engineering is developing a bioreactor where modified bacteria will consume pesticides

without large investments in building adequate sanitation facilities, more people will have inadequate sanitation

Fig. 22-18 Wastewater garden

22-6 Preventing Surface Water Pollution water pollution laws have significantly

improved water quality in U.S. improvements:

1992 to 2002, communities served by water systems meeting federal guidelines increased from 79% to 94%

fishable and swimmable streams increased from 36% to 60% of those tested

topsoil loss through runoff was cut by 111 billion metric tons annually (%?)

annual wetland losses decreased by 80%

22-6 Preventing Surface Water Pollution water pollution laws have significantly

improved water quality in U.S., cont. problem areas:

in 2000, 40% of streams and 45% of lakes surveyed were too polluted for swimming or fishing

animal waste and waste lagoons fish unsafe to eat (pesticides, Hg, etc.) in 2003, the EPA found that >50% of the

6,000 largest industrial facilities have been illegally discharging wastes into waterways

22-6 Preventing Surface Water Pollution a 2001 report by EPA’s inspector general

calls for strengthening the Clean Water Act increased funding, increased authority to

control non-point pollution, modernizing monitoring system, increasing compliance with the law

integrating watershed and airshed planning to protect ground and surface water sources

halt the loss of wetlands; increase standards for wetland restoration; and create new wetlands before filling existing ones

farmers feel they should be compensated for property value losses that result from federal regulations protecting wetlands

22-7 Drinking Water Quality 20% of people lack safe drinking water

95% of people in developed countries and 74% of people in developing countries have access to clean drinking water

the UN estimates $23 billion/yr for 8–10 yr to bring clean drinking water to those lacking it

centralized water treatment plants can provide safe drinking water; water is settled, filtered, and chlorinated

22-7 Drinking Water Quality the U.S. is upgrading water purification and

delivery systems hard to secure also difficult to adequately poison both chemical and biological indicators are

being developed to indicate contamination

22-7 Drinking Water Quality several simple, inexpensive ways for

individuals and villages to purify drinking water have been developed

exposure of contaminated water to intense sunlight in a clear plastic bottle kills bacteria

filtering water through cloth reduces risk of cholera

a small amount of chlorine in a plastic or clay storage vessel cuts the rate of diarrheal disease in half

22-7 Drinking Water Quality about 54 countries have standards for safe

drinking water levels have been established called maximum

contaminant levels for any pollutants that may adversely affect human health

privately owned wells don’t have to meet these standards

some want the standards to be strengthened certain industries want to weaken the Safe

Drinking Water Act (which industries?)

22-7 Drinking Water Quality some bottled water is not as pure as tap

water and costs much more bottled water is vastly more expensive than tap

water 1/4 is tap water 1/3 is contaminated with bacteria 1/5 is contaminated with organic chemicals

creates lots of waste manufacture releases toxic gases and liquids have home water tested be wary of companies claiming EPA approval

22-7 Drinking Water Quality we need to shift priorities to preventing and

reducing water pollution bottom-up political pressure on elected officials

has reduced point-source water pollution a shift needs to be made to how we can

prevent water pollution in the first place prevention of water pollution will take action

from individuals and groups to pressure elected officials

Fig. 22-19 Solutions

Fig. 22-20 What can you do?

` area iv: pollution iva3: water pollution. ` 22-1 types, effects, sources of water pollution l...

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