ENVIRONMENT

AL

TOXICOLOGYChapter 9

Water Pollution

Mohd Amir Bin Arshad1

Introduction

• Water pollution is

any

chemical, physical

or biological

change in the

quality of water

that has a harmful

effect on any living

thing that drinks or

uses or lives (in) it.2

Water Pollution

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• Many rivers become polluted due to the wastes that have been poured out.

• Example: Paper making industry, requires chemicals in its production. The rivers are used as an outlet for the chemicals to drain away.

Penduduk Orang asli??

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• There are some of ethnic aboriginal groups that still exist in Malaysia and they depend on the rivers and streams to survive.

• They depend on the river for food, water supply for drinking, bathing and for their crops.

Pusat Pelancongan

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• Due to tourism purpose, forestssurrounding the river areas have been chopped down.

• The surrounding soils have no roots to hold on to and soon erode when the rains come.

• The soil runs into the rivers and soon become murky.

• Threaten an aquatic life.

• A good example is the construction of a new golf course near the waterfall at tourist attraction Fraser’s Hill in the state of Pahang.

• The impact, become extremely murky and dirty due to the silt and sand that comes from the construction.

• The waterfall has now lost all its attraction.

Tasik Chini & Pollution?

• Gambar tasik chini

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• The lake water choked with coliform bacteria to levels “beyond imagination”.

• Also found in the well waters used by the orang asli in the surrounding area.

• Lake become 'blocked' sink. The water is stagnant.

• Sewage pipes from the camp lead straight into the lake.

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Main factor-built Tasik Chini National Service

Camp.

Sources of

Pollutions

Point

Source

Non-Point

Source

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Point Sources?

• Point sources discharge pollutants at

specific locations (direct) through pipelines

or sewers into the surface water.

• Examples of point sources are:

factories, sewage treatment

plants, underground mines, oil wells, oil

tankers and agriculture.

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Non-point sources?

• Non-point sources are sources that cannot be

traced (indirect) to a single site of discharge.

• Examples of non-point sources are: acid

deposition from the air, traffic, pollutants that are

spread through rivers and pollutants that enter

the water through groundwater.

• Non-point pollution is hard to control because

the perpetrators cannot be traced.

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Major Sources

Domestic IndustrialAgricultural

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Domestic pollutants

• Wastewater generated from the household

activities.

• It contains organic and inorganic materials

such as phosphates and nitrates.

• Organic materials are food and vegetable

waste, whereas inorganic materials come

from soaps and detergents.

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Domestic pollutants

• Sources of Domestic Pollutants

household product

public underground sewerage systems

septic tanks

pesticides

wastewater from dishwashers

car wash wastewater

washing machines, sinks, and baths.

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Industrial Pollutants

• Caused by the discharged of industrial effluents.

• The industrial effluents contain organic pollutants and other toxic chemicals.

• Some of the pollutants from industrial source include lead, mercury, asbestos, nitrates, phosphates, oils, etc.

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Agricultural Pollutants

• Caused by agricultural wastes:

Fertilizers

Pesticides

Soil additives

Antibiotics/drugs

Animal wastes

Washed off from the land to the aquatic system through irrigation, rainfall and leaching.

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Accident or disaster

• Oil spill is a major problem in the oceans and seas. The oil tankers and offshore petroleum refineries cause oil leakage into the waters.

• Oil floats on the water surface and prevents the atmospheric oxygen from mixing in the water.

• The oil enters the body of the organisms. It also coats the body of the aquatic animals and birds which may also kill them.

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Impact

Human Aquatic LifeEnvironment

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Effect to human

• Several type of disease/poisoning due to

consumed of contaminated water.

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Water-Borne Disease

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Heavy metal poisoning

• Exposed to

Arsenic, Lead, mercury, cadmium etc.

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Eutrophication

• Eutrophication means natural nutrient

enrichment of stream and lake water.

• Mainly caused by an increase in nitrate

and phosphate levels in water.

• Due to the enrichment, water plants such

as algae will grow extensively.

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Eutrophication

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Eutrophication

• Eutrophication also results in overgrowth

of plants like Eicchornia that covers the

entire surface of water. This reduces the

light reaching the lower layers in water.

• As a result the water will absorb less light

and certain anaerobic bacteria will become

more active.

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Eutrophication

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Hypoxia (Oxygen depletion)

• Eutrophication leads to hypoxia.

• Enrich of nutrients promoting algae

growth.

• Thus, water might turns into green.

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Hypoxia (Oxygen depletion)

• Rich algal growth leads to great increase in the number of the decomposers.

• All these life forms-decomposers, algae, other plants, fishes and other aquatic animals, use the oxygen in the water for respiration.

• This causes great demand for oxygen and results in depletion of oxygen.

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Bad Smell of Water

• When water enriched with nutrients, eventually anaerobic bacteria will become highly active.

• These bacteria produce certain gasses during their activities. Example is hydrogen sulphide. This compounds smells like rotten eggs.

• When water smells like rotten eggs we can conclude that there is hydrogen present, due to a shortage of oxygen in the specific water.

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Heat pollution

• Certain industries such as power

plants, refineries, nuclear reactors release a lot

of hot water from their cooling plants.

• Release hot water to water bodies without

reduce the temperature.

• The warmer water decreases the solubility of

oxygen in the water and it also causes water

organisms to breathe faster.

• Organisms will die from oxygen shortages.

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Acidification

• Industry emits great amounts of acidifying

gasses, such as sulphuric oxides and carbon

monoxide.

• These gasses also dissolve in rainwater.

• This causes a change in pH of the precipitation-

the pH of rain will fall to a value of or below 4.

• The lower the pH, the more acid the substance.

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Aesthetic Value

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Biomagnifications

• Pesticide (DDT) not bio-degradable. These

accumulate in the organisms.

• These organisms are fed upon by aquatic life

(fish) to the man.

• These contaminants remain in the fats and are

not degraded in the body. Over the years the

amount of DDT increases in the body.

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Biomagnifications

• Thus, pollutant reaches the body of man.

At each step in the food chain, the

contaminant increases in quantity.

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Pollution is measured by knowing the

biological oxygen demand (BOD).

Low BOD = Little Pollution

High BOD = Higher

Pollution

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Water Pollutants & EffectsPollutant Source Effect

Sewage

(domestic

wastes, hospital

wastes, excreta)

Sewerage of

rural and urban

areas.

Oxygen depletion

Spread of diseases.

Metals-MercuryIndustrial

wastes

Minamata disease - lips and

tongue, blurred vision,

deafness and mental

derangement.

LeadIndustrial

wastes

Absorbed into blood and

affects PBCs, liver, kidney,

bone, brain and the peripheral

nervous system. Lead

poisoning can even lead to

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Water Pollutants & Effects

CadmiumIndustrial,

Fertilizers

Deposited in organs like the kidney,

pancreas, liver, intestinal mucosa, etc.

Cadmium poisoning causes headache,

vomiting, bronchial pneumonia, kidney

necrosis, etc.

Arsenic Fertilizers

Arsenic poisoning causes renal failure

and death, It can cause nerve disorder,

kidney and liver disorders, muscular

atrophy, etc.

DDTPesticide

s

Accumulates in the bodies of fishes,

birds, mammals including man.

Adversely affects the nervous system,

fertility. Causes thinning of egg shells in

Pollutant Source Effect

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Water Pollution

Solutions

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Charity begins at home

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Enforcing Existing Laws

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Control

Development55

Stop Deforestation

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Preventing Oil Spills

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Prevent Emissions

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THANK YOU

Any Questions?

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