Waste materials from various sources pollute the water.

Water Pollution

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:

AGRICULTURE

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.

"Leaking pesticides can poison a very large area, making it unfit for crop production."
-- FAO expert, Alemayehu Wodageneh

INDUSTRIALISATION

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 eventually died.

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.

DOMESTIC ACTIVITIES

Waste 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 sea.

DUMPING

Sometimes, 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.