Poisons from the land


Around 77 per cent of marine pollution comes from the land - much of it from farms. Manure and fertilizers get washed into rivers and the sea, increasing nutrient levels and causing "eutrophication" - the growth of algae and seaweeds which compete with other plants and animals for space and food, ultimately killing them. Pesticides also seep into the water system, where their poisonous chemicals kill organisms and accumulate in the food chain, affecting animals' ability to reproduce.

In some parts of the world, forest clearance is the prime source of marine pollution. When loggers and developers cut forests they expose soils. Wind and rain wash these soils into rivers and eventually out to sea. Sediment builds up in coastal areas, destroying habitat and smothering wildlife.

Meanwhile, industrial processes such as metal smelting and paper, textile, and agrochemical manufacturing, all emit pollutants, or "effluent". Most factories are built near rivers so they can dump effluent straight into the water, killing first freshwater wildlife and then marine animals and plants. Many give off poisonous gases which enter the atmosphere before falling down to contaminate land and sea.

Picture of industrial pollution Industrial pollution is helping to devastate marine environments worldwide
Manufacturing, transporting goods and people, heating, and cooking can all involve the burning of fossil fuels. These give off carbon dioxide, one of the gases that many scientists believe is changing the world' s climate. One of the likely effects of global warming is that as the planet heats up, the polar ice caps will melt, causing sea levels to rise. There is therefore a risk that low - lying coastal regions such as the Nile delta could become flooded and that islands - particularly in the Pacific Ocean - might drown.


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Copyright 1996, The World Wide Fund for Nature