Introduction to Eutrophication:

Eutrophos, which means “well-nourished” in Greek, is where the word “eutrophication” originates. Extremely low-nutrient water bodies refers to as oligotrophic, and moderate-nutrient water bodies calls mesotrophic. Dystrophic and hypertrophic conditions other names for advance eutrophication. Both freshwater and saltwater systems are susceptible to eutrophication. Excess phosphorus is nearly invariably the culprit in freshwater ecosystems. However, nitrogen, or nitrogen and phosphorus together, is more likely to be the primary contributing nutrient in coastal waters.

When it happens naturally, phosphorus compounds and organic debris, in particular, build up in water bodies, a process known as eutrophication. These nutrients come from the breakdown of phosphate minerals as well as from the nutrient-scavenging action of lichens, mosses, and fungi on rocks. 

The process of anthropogenic or “cultural eutrophication” adds nutrients to a body of water more quickly. These sources include fertilizer runoff, industrial effluent, and untreated or poorly treated sewage. This type of water pollution, known as nutrient pollution, and is the main factor behind surface water eutrophication, a process in which an overabundance of nutrients, typically phosphorus or nitrogen, promotes the growth of aquatic plants and algae. One of the primary causes of algal growth, primarily cyanobacteria, is phosphate. In order to control algal bloom and hasten the recovery of eutrophic water bodies, Geo-engineering materials employing.

Algal blooms are a frequent, observable result of eutrophication. Algal blooms may only bother people who wish to use the body of water, or they may develop into dangerous blooms that seriously destroy the ecosystem of the body of water. After the algae is broken down by microorganisms, this process could cause the water body to become oxygen-depleted.


Eutrophication is mainly divided into natural and cultural eutrophication. Where in natural eutrophication, a lake is characterized by nutrient enrichment. During this process an oligotrophic lake is converted into a eutrophic lake. It permits the production of phytoplankton, algal blooms and aquatic vegetation that in turn provide ample food for herbivorous zooplankton and fish.

When the process of Eutrophication is increased by the human activities, it is called cultural eutrophication. This is because the human activities (mainly development in nature) increase the surface run off and the nutrients such as phosphates, nitrates, are supplied to the ocean water. They may be supplied by construction works, treatment plants, golf courses, fertilizers, and farms. Human activities are responsible for addition of 80% nitrogen and 75% phosphorous to lakes and streams.


The principal source(s) of nutrient pollution in an individual watershed depend on the prevailing land uses. The sources may be point sourcesnon point sources, or both:

Point source pollution: contamination caused by substances that enter a river from a single, recognizable source, like fixed infrastructure or stationary places. Fish farms, industrial plants, and sewage treatment facility discharges are a few examples.

Non-point source pollution: pollution from human activity that is widely distributed and does not have a single point of entry or discharge into receiving watercourses. Examples include losses from air deposition and nitrogen compounds seeping out of fertilised agricultural areas.

Some of the examples determining the causes of the eutrophication is as follows-

  • Agriculture: raising crops or animals
  • Urban and suburban areas: stormwater runoff from parking lots and roadways; overuse of fertiliser on lawns; municipal sewage treatment plants; emissions from motor vehicle.
  • Industrial: wastewater discharges from different industries, and air pollution emissions from sources including electric power plants.

Excessive quantities of nutrients, most frequently phosphate and nitrate, are the cause of eutrophication. Aquatic plants, including macrophytes and phytoplankton, grow quickly in environments with high nitrogen concentrations. Invertebrates and fish species increase in tandem with the amount of plant material that is accessible as a food source. The process results in a loss in biological diversity and an increase in the water body’s biomass. The phosphates in fertilisers and detergents are the sources of excess phosphate.

With the phasing out of phosphate-containing detergents in the 1970s, industrial/domestic run-off, sewage and agriculture have emerged as the dominant contributors to eutrophication. The main sources of nitrogen pollution are from agricultural runoff (from fertilizers and animal wastes), from sewage and from atmospheric deposition of nitrogen originating from combustion or animal waste.

Strongly eutrophic freshwaters can become hypoxic throughout their depth following severe algal blooms or macrophyte overgrowths. Similarly, in marine systems, both increasing nutrient concentrations and isolation of bodies of water from contact with the atmosphere, can lead to depletion of oxygen which can make these waters inhospitable to fish and invertebrates.


  1. Since agriculture contributes significantly to eutrophication, it is important to address this issue. For example, recycling animal dung to croplands inside watersheds can lessen the amount of nutrients that seep from farmland.
  2. Landscape preservation and restoration, particularly at land-water interfaces, encourages denitrification processes and lowers the amount of nutrients discharged into coastal waterways.
  • Among the methods to prevent eutrophication is composting. For example, it can aid in the conversion of organic matter—such as leftover food and decomposing vegetation—into compost manure, which is lacking in nutrients due to its high nitrate and phosphate content, which nourish algae and other microorganisms in water bodies.
  1. It is simple to regulate eutrophication with the aid of strict rules or policies crafted by legislators, citizens, pollution regulating agencies, and the government. For example, laws that minimize non-point pollution would reduce the amount of nutrients that enter aquatic ecosystems.
  2. Oxygenating water to counteract the detrimental impacts of eutrophication and restore ecological conditions, such as low oxygen levels and the production of harmful chemicals from anaerobic metabolism.

Sources NCERT, Wikipedia