5. water pollution

8/13/2019 5. Water Pollution

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Seen Environmental Learning Information Sheet No 5 1

The importance of waterThe earth's surface is 75% water, but out of this

only 3% is fresh water, of which only 1% is

available for people to use. Water sustains life

for humans, animals and plants. People need

water for basic everyday activities like drinking

and cooking, but water is also very important for

the fuelling of agriculture and industry, and plays

an important role in the nature of national

economies.

However the supply of freshwater available to

humanity is shrinking. One of the main causes of

this is the polluting of many freshwater

resources. In some countries lakes and rivers

have become polluted with an assortment of

waste, including untreated or partially treated

municipal sewage, toxic industrial effluents,

harmful chemicals, and ground waters from

agricultural activities. Polluted water supplies not

only limit water availability but also put millions

at risk of water-related diseases.

The lack of freshwater is likely to be one of the

most critical natural resource issues facing

people in the next 50 years. The world's

population is expanding rapidly, yet our supplies

of freshwater are not, placing greater demand on

our water resources. This makes it even more

important that the remaining freshwater we have

is kept safe and clean.

Pollution problemPollution is everywhere. Few countries have

adequately safeguarded water quality and

controlled water pollution. Many countries do

not have standards to control water pollution

adequately, while others cannot enforce water

quality standards. The consequence of having

polluted water is:

A reduction in water quality which leads to

health problems

The endangerment of agriculture and

aquatic ecosystems.

Water pollution occurs when a body of water is

affected with large amounts of harmful

substances. When water is considered unfit for its

intended use, it is called polluted. There are two

types of water pollutants; point source and non-

point source. Point sources of pollution occur

when harmful substances are emitted directly

into a body of water, for example an instancewhere there is an oil spill. A non-point source

delivers pollutants indirectly through

environmental changes, for example when

fertiliser from a field is carried into a stream by

rain.

Pollution of rivers and lakes reduces accessible

freshwater supplies. Each year roughly 450 cubic

kilometres of wastewater are discharged into

rivers, streams and lakes. To dilute and transport

this dirty water before it can be used again,

another 6,000 cubic kilometres of clean water are

needed - an amount equal to about two-thirds of

the world's total annual useable fresh water

runoff.

Pollution from untreated sewerage

In developing countries statistics suggest that

almost all sewerage that is deposited into rivers,

lakes and the ocean are untreated. This causes

significant health risks, as water carrying

untreated sewerage is a potential source of water-

borne disease. The effects can be far reaching, ifthe water is used to grow crops that are then

eaten uncooked then disease can spread to a

whole community.

Underground pollution

Underground water supplies are particularly

susceptible to pollutants. Any pollutants that are

deposited underground can adversely affect water

supplies. Different pollutants include:

Landfill sites and rubbish dumps

Buried harmful waste e.g. Fuel tank

Water PollutionSeen Environmental Learning Information Sheet no 5

Health and the Environment


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Theme:Health and the EnvironmentTopic No 5:Water Pollution


Industrial or mining waste

Human waste

Agricultural pollutants

Agriculture is the biggest polluter. In virtuallyevery country where agricultural fertilisers and

pesticides are used, they have contaminated

groundwater aquifers and surface waters. Animal

wastes are another source of pollution in some

areas.

The water that goes back into rivers and streams

after being used for irrigation is often severely

degraded by excess nutrients, salinity, pathogens,

and sediments that it is unfit for further use

unless cleaned by water purification plants which

is very costly.

Industrial pollutants

Wastes from industries have increased

enormously in recent decades. They not only

affect freshwater supplies and everything

dependent on them, but also marine life. Between

200 and 400 major chemicals are estimated to

contaminate the world's rivers. Industrial

pollutants, such as wastes from chemical plants,

are often dumped directly into waterways while

oils and salts are washed off city streets.

Pollutants such as sulphur dioxide and oxides of

nitrogen combine in the atmosphere to form

acid rainhave had terrible effects on both

freshwater and land ecosystems. Acid rain lowers

the ph of rivers and streams. Unless buffered by

calcium (as contained in limestone), acidified

waters kill many acid-sensitive fish, including

salmon and trout. In the soil, acids can release

heavy metals, such as lead, mercury, and

cadmium, which can then infect water supplies.

Some of the worst pollutants are syntheticchemicals. Some 70,000 different chemical

substances are in regular use throughout the

world. Every year an estimated 1,000 new

compounds are introduced. Many of them find

their way into rivers, lakes, and groundwater

aquifers.

A particular group of synthetic chemicals are an

immense threat, these are known as

persistent organic pollutants (pops):

DDT- this is an insecticide mainly used to

kill mosquitoes, flies, fleas, lice andagricultural pests.

Dioxins- these chemical compounds occur

as a by-product of industrial processes like

paper bleaching, and also when plastics are

burnt.

PCBs (polychlorinated biphenols)-

chemicals used to manufacture items like

transformers, pumps, plastics, paints andadhesives.

They are long-lived and highly toxic in the

environment and not break down easily undernatural processes. Thus they tend to affect all

species up food chain, until they pose risks to

human health.

Water pollution in NamibiaNamibia has a very dry climate and therefore

does not have much fresh water. Water pollution

is a main concern to the country. With water

already being limited, Namibia cannot afford to

have any polluted waters. Pollution has become akey issue since Namibia has become more

economically and industrially developed. This

means that more waste is generated, largely in

the form of deposited chemicals. Water pollution

in Namibia is largely of two types:

Toxic chemicals pesticides, heavy metals

and chemicals

Organic material largely sewage but alsosilt and soil from run-off

Because of the low level of industrialisation in

Namibia, the latter are a more dangerous threat,although the mining and leather tanning

industries can be major polluters at specific sites.

In Windhoek there are strict guidelines for the

type of industrial effluent that can be discharged

into the municipal sewer system and regular

inspections are carried out. Industries that may

produce heavily polluted effluent are also not

allowed within the drainage area where water is

reclaimed.


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A major threat to groundwater however comes

from rainwater flowing through landfill sites

where hazardous waste has been disposed of by

individuals and industry. Although special waste

disposal sites exist at Windhoek and Walvis Baythey are not always used. Leachate from landfill

sites is usually more polluted than sewage and

more difficult to treat.

Sources of organic pollution include:

Dirty water around water points, seepage

from pit latrines or septic tanks

Animals around water points

Washing and bathing near a water source

Using the bush toilet

Urbanization and population increases cause

more problems as they put more demand on fresh

water supplies and increase the risk of pollution.

Pollutants from industrial and economic

development threaten the survival of many

wildlife animals by contaminating and taking up

their water supply.

Pollution issues in the coastal zone

of the Erongo region

The pollution problems in the Erongo region areassociated with commercial and urban activities,

especially in and around the Walvis Bay harbour

area.

The fishing industry is a major polluter of the

seawater in Walvis Bay due to lack of discharge

treatment measures. Effluent wash water is led

directly into the sea where there is water intake

for the fish processing plants. Minor oil spills,

discharge of waste containing traces of anti-

fouling paints, sewage from ships and heavymetals from the export of semi-processed mine

ore, also contribute to the pollution of the sea

water in the harbour and bay area.

Solid waste, sewerage and small amounts of oil

products produced at the ships are occasionally

dumped into the sea resulting in wastes being

washed ashore on the beaches between Walvis

Bay and Swakopmund and in the port of Walvis

Bay.

The waste dumpsite at Walvis Bay may pollute

the ground water as the water table at the site

coincides with the lower level of the dump.

Underground pollution may also occur from the

Rssing uranium mine. However, the mine hasdeveloped an extensive programme for

wastewater recovery. Moreover, monitoring

operations in the vicinity of the mine seems to

secure that potentials impacts on the surrounding

nature is minimal.

Lack of environmental awareness among some

local residents and holiday visitors causes

littering of the beaches and the desert, i.e. Plastic

bags, paper, cans, bottles and fishing lines.

Legislation in Namibia

Currently the Walvis Bay-based Environmental

Action Trust (EAT) of Namibia is tackling

government on its legal responsibilities for

pollution around harbours. There is also

legislation from 1956 and 1958 that, along with

the Sea Fisheries Act of 1992, places the

responsibility for protecting Namibia's harbours

and fishing grounds from pollution with the

government. A polluter can be fined up to N$1-

million and/or face 15 years in jail. The 1958

legislation also guards against effluent beingdischarged into the sea, including toxic paint

being scraped off or applied at the harbour's

syncrolift. The sea fisheries act of 1992 makes it

illegal to dump anything "injurious to fish, fish

food or aquatic plants", to disturb "the ecological

balance in any area of the sea", or to "wilfully or

negligently pollute any water including the sea".

Currently three government ministries have been

charged with ignoring parts of these laws!

Some argue that stronger legislation and

enforcement measures are required to ensure that

the principle of the polluter paying is fully

implemented. This principle recognises that the

polluter should pay for any environmental

damage created and that the burden of proof for

showing that a particular technology is safe lies

with the developer, not the general public.

Unfortunately as experience with the Ramatex

textile factory has shown, because of inadequate

controls, it is often unclear how much pollution

has been caused or whether enforcing the

Municipal regulations is practically possible.


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ConclusionOveruse and pollution of the world's freshwater

resources are a recent development. Their long-term consequences are still unknown. Already,

however, they have taken a heavy toll on the

environment, and they pose increasing risks for

many species. Polluted water and lack of

sanitation also greatly risk human health.

Moreover, the state of freshwater resources

contributes to the deterioration of coastal waters

and seas. It is therefore critical that more care is

taken to reduce pollutants in our fast retreating

freshwater supplies.


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Important ideas to stress in your teaching and learning The earths supply of freshwater is limited. Providing clean water to all is likely to be the biggest

environmental challenge in the 21st century.

Water pollution by sewage, toxic industrial effluents, harmful chemicals, and ground waters fromagricultural activities limit water availability and spread water-related diseases.

Water is scarce in Namibia so preventing water pollution is a major priority. Most water pollutionis from organic waste.

Water pollution is best prevented through education and legislation that implements and monitorsthe polluter pays principle because the costs of treating polluted water are very high.

Glossary

Ecosystem A group of interdependent organisms together with the environment theyinhabit and depend on.

Effluent Liquid waste discharges from a sewage system, factory, nuclear power station,

or other industrial plant.

Industrialisation The adoption of industrial methods of production and manufacturing by a

country, with all the associated changes in lifestyle, transport, and other aspects

of life.

Legislation A law or laws passed by an official body, especially a governmental assembly.

Organic Relating to or derived from living things.

Pesticide A chemical substance used to kill pests, especially insects.

Pollution Things that pollute or cause harm to an area of the natural environment, forexample, chemicals or waste products that contaminate the air, soil, or water.

Urbanisation The accustoming of somebody to living in a town or city rather than in the rural

areas, and the causing of people to migrate to a town or city from the rural

areas.

Sources/Further ReadingWater Pollution, National Water Awareness Campaign

The Gaia Atlas of Planet Management

The Guardian August 22 2003

5. water pollution

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