More oil from land than from spills
Oil spills cause huge damage to the marine environment - but in fact are responsible for only around 12% of the oil entering the seas each year. According to a study by the US National Research Council, 36% comes down drains and rivers as waste and runoff from cities and industry.
Fertilizer woes
Fertilizer runoff from farms and lawns is a huge problem for coastal areas. The extra nutrients cause eutrophication - flourishing of algal blooms that deplete the water's dissolved oxygen and suffocate other marine life. Eutrophication has created enormous dead zones in several parts of the world, including the Gulf of Mexico and the Baltic Sea.
Seas of garbage
Solid garbage also makes its way to the ocean. Plastic bags, balloons, glass bottles, shoes, packaging material - if not disposed of correctly, almost everything we throw away can reach the sea.
Plastic garbage, which decomposes very slowly, is often mistaken for food by marine animals. High concentrations of plastic material, particularly plastic bags, have been found blocking the breathing passages and stomachs of many marine species, including whales, dolphins, seals, puffins, and turtles. Plastic six-pack rings for drink bottles can also choke marine animals.
This garbage can also come back to shore, where it pollutes beaches and other coastal habitats.
Sewage disposal
In many parts of the world, sewage flows untreated, or under-treated, into the ocean. For example, 80% of urban sewage discharged into the Mediterranean Sea is untreated.
This sewage can also lead to eutrophication. In addition, it can cause human disease and lead to beach closures.
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