Ocean pollution
Ocean pollution
phosphorous). Eutrophication can trigger toxic algal blooms and cause “dead zones” (oxygen depletion) in the ocean and coastal waters leading to significant
The oceans are under increasing stress from multiple
loss of marine biodiversity. Excessive nitrogen in the
urban and rural sources of pollution, notably solid and
environment also contributes to climate change,
liquid wastes from cities, pharmaceutical residues,
depletion of the ozone layer, air pollution, nitrate toxicity
fertiliser and manure run-off from farming, air
in groundwater and drinking water, loss of biodiversity
emissions from shipping, and incorrect disposal of
and deterioration of soil quality.
plastic from land-based and sea-based sources. Figure 4 shows coastal and ocean sites where
Eutrophication and ocean dead zones are a growing global challenge
anthropogenic nutrients, such as nitrogen from fertilisers and livestock manure, have exacerbated or caused low oxygen levels (shaded blue areas), leading to the
Globally, one of the most prevalent water quality
formation of dead zones (red dots). The number and size
challenges is eutrophication; a form of water pollution
of ocean dead zones has doubled each decade since the
caused by excess use of nutrients (nitrogen and
1960s, mostly due to nutrient pollution from agriculture.
The number and size of ocean dead zones has doubled each decade since the 1960s, mostly due to nutrient pollution from agriculture.
OCEAN POLLUTION . 9
