Waste materials from various sources pollute the
Water pollution occurs when waste materials from
agriculture, industries and domestic sources are discharged into
rivers, lakes and seas.
How does water get polluted?
Water pollution is caused
by the following activities:
- To increase
the amount of food produced, farmers use large amounts of chemical
fertilisers and pesticides. The excess chemicals not used by the
plants are washed by the rainwater into rivers, lakes and seas,
polluting both surface water and underground water. In a new
report, the UN Food and Agriculture Organisation (FAO) says almost
500,000 tonnes of old and unused toxic pesticides have been
abandoned on sites.
pesticides can poison a very large area, making it unfit for crop
-- FAO expert, Alemayehu Wodageneh
Factories and industries
often release poisonous chemical substances into seas, rivers or
lakes, resulting in the destruction of Mother Nature. An example of
industrial sea pollution happened in Japan in the 1950s. A local
factory had poured waste water containing mercury into the Minamata
Bay for 20 years. Tuna fish in the bay absorbed the mercury and
people ate the tuna. Many children were hence borned with birth
deformities, people lost their hearing ad sight and thousands
- SEA TRANSPORTATION
- When ships
transporting oil from one country to another get damaged en route,
oil spillage occurs. One historic major disaster was the Exxon
Valdez oil spill, in which an oil tanker sank off Alaska in 1989,
leaking 240 000 barrels of oil into the ocean. To save cost, some
ships also illegally dump unwanted oil from their engine rooms into
the sea, thus polluting the oceans.
products from the washing of clothes, dishes and lavatories, if
untreated and discharged into the sea, promote the growth of algae
which destroys marine life. Infectious diseases may also spread if
sewage is not treated before it is discharged into the
rubbish irresponsibly dumped into the sea. There had been cases
where fishes get tangled in old fishing nets or feed on packaging
styrofoam and they die.