Facts and Figures

Projected food production needs suggest a 10%-15% increase in the river input of nitrogen loads into coastal ecosystems

  • Globally, the most prevalent water quality problem is eutrophication, a result of high-nutrient loads (mainly phosphorus and nitrogen).
  • Major nutrient sources include agricultural runoff, domestic sewage (also a source of microbial pollution), industrial effluents and atmospheric inputs from fossil fuel burning and bush fires.
  • Excessive nutrient inputs can also cause harmful algal blooms. Cyanobacteria, also known as blue-green algae, have increased in freshwater and coastal systems such as the East China Sea in recent decades.  The toxins produced by the excessive algal blooms are concentrated by filter-feeding bivalves, fish and other marine organisms and can cause fish and shellfish poisoning. In people they can cause acute poisoning, skin irritation and gastrointestinal illnesses.
  • Pesticides tend to migrate throughout the environment, ending up in fatty tissues (fish) and sediments,  creating adverse environmental effects. Pesticide contamination has increased rapidly since the 1970s, particularly in freshwater in developing countries, despite increased regulation of the use of these bioaccumulating and highly persistent substances.
  • Projected food production needs and increasing wastewater effluents associated with an increasing population over the next three decades suggest a 10%-15% increase in the river input of nitrogen loads into coastal ecosystems, continuing the trend observed during 1970-95.

Related themes: Food and Agriculture; Ecosystems

Back to top