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Our Impact on the Ecosystem (Sewage (Untreated sewage contains phosphates…
Our Impact on the Ecosystem
Deforestation
Reasons
Urban development
Cultivation
Grazing
Fibres
Timber
Effects
Soil Erosion
Flooding
Desertification
Climate Changes
The Need for Conservation
Pollution
defined as
the addition of substances to the environment that damage it, making it undesirable or unfit for life.
Inorganic waste
may contain poisonous metals such as mercury, lead, zinc, arsenic and cadmium.
Villagers who eat the fish, of which have high concentration of poisonous metals in their body already, will die of poisoning.
Insectides
Disadvantages
may become ineffective after some time
may end up affecting organisms other than insects
DDT( dichlorodiphenyltrichloroethane) is non biodegradable; cannot be broken down
insoluble in water, therefore is not excreted; stored instead in fatty tissues of organisms
accumulates in bodies of consumers;if consumers keep on consuming food that contains DDT , conc. of DDT will further increase. (
Bioaccumulation
)
DDT being passed along food chains; increasing conc. in bodies of organisms along the trophic levels (
Bioamplification
)
Top consumers in a food chain accumulate large amount of DDT and they suffer toxic effects
Over-fishing
As human population increase, so does the demand for fish. Some species of fishes have been caught in such large numbers that their population decrease drastically.
Indiscriminate fishing
not distinguished btwn the targeted and non-targeted catch
Methods of fishing
Drift nets
Use of shrimp or prawn trawlers
Scallop dredges
Cyanide fishing
Sewage
Untreated sewage contains phosphates and nitrates, which are nutrients for algae and water plants. This can lead to
eutrophication
Overcrowding of algae and water plants prevent sunlight from reaching the submerged plants
Submerged plants die due to lack to sunlight. Dead algae and water plants are decomposed by aerobic bacteria and fungi
As bacteria feed on decaying organic matter, they grow and multiply rapidly, using up oxygen
Other organisms die due to lack of oxygen