It is derived from the Greek word “Eutrophic (well-nourished)” which means a state of normal nourishment and growth. Eutrophication is a syndrome of ecosystem typically of a water body. The water body (lake or pond) becomes overly enriched with minerals and nutrients which induce excessive growth of algae.
Artificial addition of nutrients such as nitrates and phosphates through fertilizers, industrial or agricultural effluents sewage, etc. that fertilize the aquatic ecosystem.
This on-going fertilization of water body causes algal blooms and consequent depletion of dissolved oxygen and eventually causes the death of species and water body.
Eutrophication can be natural and cultural:
Natural Eutrophication: The nutrient enrichment of the water bodies- lakes -promotes the growth of algae, aquatic plants and various fauna. This process is called natural eutrophication.
Cultural Eutrophication: The nutrient enrichment of water bodies – lakes- at an accelerated rate is caused by human activities (industrial discharge of wastewaters or agricultural runoff) and the consequent ageing phenomenon is known as ‘cultural eutrophication’.
Sources of Eutrophication
There are two types of sources:
Point sources:
A definite and identifiable source of water pollution. For example, Factories, Oil refineries, paper mills, auto plants and sewage treatment plants are point sources.
Non-Point sources:
It is a non-identifiable source of pollution. For example, rainwater runoff mixes with fertilizers and industrial wastes and garbage waste etc. flow into rivers. cause acid rain results from the long-range movement of those pollutants from many factories and power plants, acid rains are an example of a non-point source of pollution.
Causes of Eutrophication
- Industrial discharge: Industrial effluents and wastewater discharge into rivers, streams, lakes and ponds
- Urbanisation:
- Untreated sewage discharges golf courses, parks, etc. into water streams
- Combustion of fossil fuel emitting gases – nitrogen oxides etc.
- Agricultural Runoff: Runoff of fertilizers (Nitrogen, Phosphorous and Potassium etc.) from Agricultural fields and animal wastes.
Effect of Eutrophication
Eutrophication causes many adverse effects on the aquatic ecosystem:
- Death of species:
- Aquatic plants are dying due to the lack of availability of sunlight for photosynthesis.
- Death of aquatic animals due to depletion of dissolved oxygen, which is totally consumed by bacteria to decompose the dead organisms.
- Loss of biodiversity: The number and diversity of plant and animal species in eutrophic lakes are less compared to oligotrophic lakes (very low nutrients).
- Toxicity: Certain algal blooms when die or are eaten, release harmful toxins- neuro & hepatotoxins- which can kill the aquatic organism and also risk human health. For example, Shellfish poisoning in humans.
- Water contamination: Turbidity and foul-smelling of water.
- Shallow Depth: Eutrophics cause the formation of a detritus layer in the ponds & lakes due to algal blooms and reduce the depth of the lake.
Suggestions
- Treatment of wastes before discharge.
- Emission limits on harmful gases etc.
- Strict regulations against the indiscriminate discharge of untreated water from Industries.
- Review policies- revoke fertilizer subsidies and move towards green methods or sustainable forms of agriculture- Precision Agriculture, Zero-budget Natural Farming, etc.
- Integrating ecological perspectives in development models and economic activities.
Way Forward
There is an urgent need for striking a balance between development and the environment for ensuring sustainable development. Hence, stringent policies limit the irresponsible discharge of effluents into water bodies and the emission of harmful gases.
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