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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
3
• 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??
6
• 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
8
• 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
11
• 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.
27
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
32
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.
35
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
37
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
46
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.
48
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
50
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
51
Water Pollution
Solutions
52
Charity begins at home
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Enforcing Existing Laws
54
Control
Development55
Stop Deforestation
56
Preventing Oil Spills
57
Prevent Emissions
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60
THANK YOU
Any Questions?
61
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