Global Impacts of Water Pollution

Eutrophication: It refers to the enrichment of freshwater bodies by inorganic nutrients, and phosphates which may occur naturally but more readily as the result of human activity. It is predominantly apparent in sluggish rivers and shallow lakes.

Nutrient over amelioration of freshwater and coastal ecosystems is a rapidly growing environmental emergency. The number of coastal areas affected by eutrophication globally is over 500. High amounts of nitrates and phosphates are present in sewage, fertilizers, and other organic matter. A eutrophic water body has high primary productivity due to excessive nutrients and hence favors the growth of algal blooms resulting in poor water quality.

Bio-accumulation and Bio-magnification: Bio-accumulation is the accretion of substances like pesticides, metals, and various organic compounds into the body of a living organism over a period of time. This can occur either because the chemical gains entry faster than it can be utilized. Thus, the longer the biological life of the substance the greater the risk of chronic poisoning, even if its level in the environment is not very high.

Bio-magnification is also known as Bio-amplification. It is the amplification in concentration of a substance up the trophic level. This occurs in a food chain as a result of

  • It is persistant.
  • Energetics of the food chain.
  • Low rate of internal metabolism and excretion of the substance.

Bio-magnification is the process by which particular substances such as pesticides (DDT) or heavy metals (mercury) go up the trophic level. These chemicals are often released into rivers or lakes, gains access to phytoplanktons and zooplanktons. They are consumed by aquatic organisms such as crustaceans, rotifers, snails, and fish which in turn are consumed by large birds, animals, or humans. Each time, as they go up the trophic levels in the food chain, the substances become deposited and concentrated in tissues or internal organs.