Biology Form 4

BIOLOGY FORM 4CHAPTER 9 TITLE: Water Pollution and Eutrophication Group Member: Chong Jin Zong Wong Jing Jie Ting Ting Rong Tan Thai Hong Wong Yew Ung Tiong Wee Kuok

Water pollution is any chemical,biological, or physical change in water quality that has a harmful effect on living organism or make water unsuitable for desired uses.

The Causes of Water Pollution• Sewage and waste water• Radioactive waste• Eutrophication• Industrial waste• Global warming• Underground Storage leakages• Atmospheric Deposition• Marine Dumping• Oil Pollution

TABLES OF SOURCES, POLLUTANTS, AND EFFECTS OF WATER POLLUTION

EFFECT OF WATER POLLUTION

• Addition of oxygen not sufficient to support life.• Addition of oil destroys life by reducing oxygen and catching fine, destroying ecosystem.• Reduced reproduction rate of animals.• Increased incidence of disease.• Imbalance created in secondary food chains.• Reduced activity of immune system.

Eutrophication

Eutrophication is a natural process occurring on places where water flows (slow streams, lakes, estuaries), naturally or by human activity, become enriched with nutrients and excessive plant growth appear.

Rapid growth of algae, bacteria and sea weed. Competition between species appear for the limited amount of vital sources=> less stronger one disappear =>specie richness in aquatic life is reduced.

Algal Blooms and the ecological effects.

• Algal bloom is a result of the nutrient enrichment in the aquatic system.• When the water is enriched by nutrients,it stimulates the bloom of the algae and its populatiob rapidly expands. When sinks from the algae to the bottom of the

water source starts decomposing, which becomes a perfect habitat for bacteria.The population of the bacteria increases and it need too much oxygen.• Organisms start lacking oxygen and die.• Algar Bloom also blocks the sunlight, which leads to stop the photosynthesis and reducing the temperature of the water source.

1. The densely populated algae cover the water surface and block the sunlight.Unable to carry out photosynthesis,the aquatic plants die.• When these plants die,aquatic animals lose their food sources and habitats.As a result, the food chain and ecosystem change.• Algae also reduce the level of dissolved oxygen in the water.2. When the algae and other aquatic organisms die,decomposing organisms especially saprophytic bacteria use up oxygen to decompose the dead organice materials.• This reduce the oxygen content in the water.

Algal blooms endanger the ecosystem in two ways

Effects• The excessive nitrogen and Phosphorus cause rapid growth of phytoplankton( consumes much oxygen) and algal blooms, leading to reduction of the growth of other

platns, also marine animals.• When phytoplankton is stimulated by factors such as fertilizers and nutrients to grow, less and less oxygen is left for the system.• This organic matter sinks to the bottom and makes it even harder for other living organisms to exist.• Such severe Eutrophication can cause serious threats to both humans and nature.• 72% of the USA shrimps are supplied from this gulf, 66% of all oysters and 16 % of fish.

Ways of Preventing

• Use of fewer fertilizers to limit wastes,released in the river.• Control of animal wastes.• The industrial practices, such as the releasing of nitrogen or nutrients,responsible for the eutrophication.• Production of Wetlands along the coast, so the water can be filtered.

Managing Eutrophication

• In order to handle eutrophication nutrient avaibility should be reduced.• Three main methods: 1.Precipation, 2.Removal of nutrient, 3.Removal of biomass• Common examples of these methods are harvesting,removal of terrestrial vegetation and treatment with aluminium of ferrous salts solutions.

Examples

• Eutrophication is common in the Potomac River.• The colour og the water has turned from normal to bright green.• Cause by a large amount of cyanobacteria.

A depletion in oxygen results in an increase in biochemical oxygen demand(BOD)Eutrophication increase the BOD value in the water.

BOD refers to the amount of oxygen utilized by microorganisms to oxidise all organic matter in one litre water.

The higher the Bod value, the more polluted the water as the dissolved oxygen level decrease

What is BOD?

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