Eutrophication is the process where a body of water becomes enriched with nutrients, often resulting in excessive plant growth and lack of oxygen. This summary discusses the causes and impacts of eutrophication in freshwater bodies. Nutrient pollution from sources like sewage, fertilizers, and livestock waste can cause cultural eutrophication. As nutrient levels rise, plant and algal growth increases, reducing water clarity and oxygen levels. Long term, a lake may transform from an oligotrophic to eutrophic state, changing the ecosystem. Eutrophication harms the environment and human uses of the water through impacts like algal blooms, loss of biodiversity, and health risks. Various methods can help control

1. EUTROPHICATION AND ITS CONTROL
SUBMITTED TO: SUBMITTED BY:
DR. S.K. SINGH SHIVANI GUPTA
HOD (ENV) 2K21/ENE/10

2. CONTENTS
1. INTRODUCTION
2. BASIC CONCEPT RELATED TO WATER BODY
3. EUTROPHICATION
4. TYPES OF EUTROPHICATION
5. SOURCES OF NUTIENTS
6. MECHANISM
7. EUTROPHICATION EVALUATION METHODS
8. CONTROL
9. CASE STUDIES
10. REFERENCES

3. INTRODUCTION
 In earth’s hydrosphere, fresh water comprises only 3% of the
total water in the earth system.
 Because most fresh water is held in glaciers and polar ice caps,
only ~30% of fresh water reserves are available as surface water
or groundwater for human use (Earth material and Health,2007)
 Fresh waters are low-salt water, usually present in lakes, ponds
and streams and have a concentration of salts usually less than
500mg/l (P. K. Goel, 2006)
 Nutrient pollution, which includes nitrates and phosphates, is the
leading type of contamination in these freshwater
sources.(NRDC)
Fig 1: Distribution of the world’s water (Earth
material and Health,2007)

4. ZONES OF LAKE
Fig 2: Different zones of lake based on temperature profile(P. K. Goel, 2006)
Summer
Winter
Euphotic
Bentic

5. PRODUCTIVITY OF LAKE
 A lake’s ability to support plant and
animal life defines its level of
productivity, or trophic state
 Lakes are classified based on
productivity, or how much
photosynthesis is occurring in the
water:
1. Oligotrophic
2. Mesotrophic
3. Eutrophic
4. Senescent
Fig 3: Lake classification based on productivity
https://facultystaff.richmond.edu/

6. STRATIFICATION AND DO
Fig 4: Annual shifts in lake stratification, in a temperate ecosystem, with changes in dissolved oxygen and temperature with depth
(https://lakeecosystems2014.wordpress.com/)

7. EUTROPHICATION
 Eutrophication is the process of enrichment of nutrients in an aquatic ecosystem (Weber,1907).
 The process whereby a body of water becomes rich in dissolved nutrients through natural or man-made
processes. This often results in a deficiency of dissolved oxygen, producing an environment that favors
plant over animal life (Brenda,2009).
 A young lake is characterized by a low nutrient content and low plant productivity. Such oligotrophic
(“few foods”) lakes gradually acquire nutrients from their drainage basins, which enables increased
aquatic growth.
 Over time, the increased biological productivity causes the water to become murky with phytoplankton,
while decaying organic matter contributes to the depletion of available dissolved oxygen.
 The lake becomes eutrophic (“well fed”). As the accumulating silt and organic debris cause the lake to
get shallower and warmer, more plants take root along the shallow edges, and the lake slowly transforms
into a marsh or bog.

8. Fig. 5: Hungabee Lake (left), in the Canadian Rockies, is a crystal clear blue lake. In contrast, Lake Taihu (right)
in China is considered a highly eutrophic lake; its bright green color
https://www.lakescientist.com

9. TYPES OF EUTROPHICATION
 Natural Eutrophication is a process
that a lake goes through over hundreds
to thousands of year
 It also some times referred as lake
aging
 Cultural eutrophication (excessive
plant growth resulting from nutrient
enrichment by human activity) is the
primary problem facing most surface
waters today
 It is one of the most visible examples
of human changes to the biosphere
(Smith,2003).
Fig 6: A comparison of natural eutrophication and cultural eutrophication
https://teamwork.niwa.co.nz/pages/viewpage.action?pageId=64127148

10. SOURCES OF NUTRIENTS
 The untreated domestic sewage and garbage coming out from nearby areas
 Use of inorganic fertilizers, detergents, insecticides and pesticides like toxic compounds and livestock
wastes inters in lake
 Runoff from agricultural and urban nonpoint-sources.
 Hygienic activities are carried out by the local people in the fresh water springs and used waste water enters
in lake at last (Vyankatesh, 2013)
 Autotrophy algae blooming in water, which composes its bioplasm by sunlight energy and inorganic
substances through photosynthesis—the process of eutrophication is described as follows:
106 CO2 + 16 NO3
- + HPO4
2- + 122 H2O + 18 H+ C106H263O110N16P + 138 O2
 According to above equation, it can be concluded that inorganic nitrogen and phosphorus are the major
control factors for the propagation of algae, especially phosphorus.(yang,2008)
 Nitrogen enters water as “fallout” from combustion sources, particularly fossil-fuel-fired power plants.
With the atmosphere providing a rather unlimited nitrogen supply, most freshwater systems are phosphorus
limited (Zhang,2020)
Energy+microelement
(Bioplasm of algae)

11. Fig 7: (a)Sources of nutrient inputs and the cycling of nutrients in the water body (b)Demonstration of eutrophication
and its effects in the water body (Zhang,2021)

12. https://www.pmfias.com/water-pollution-biological-oxygen-demand/
MECHANISM OF EUTROPHICATION
Fig 8: Mechanism of eutrophication in a water body

13. EFFECT OF EUTROPHICATION
Environmental Impact Socio-Economic Impacts Human-health Impacts
Decrease transparency of
water(Increased turbidity )
Disappearance of commercially
important species(such as trout)
Harmful algal bloom species have the
capacity to produce toxins dangerous to
humans
Decrease in species
diversity(biodiversity)
Loss of tourism/ recreation
(swimming, boating)
Risk for seafood consumers: Toxin
accumulate in shellfish and more generally
in seafood reaching dangerous levels for
human as well as animal health
Change in dominant biota(eb. Change in
plankton structure or change in fish
composition)
Loss of aesthetic value: Visual
disamenity of algal bloom in lake
If water consume without proper treatment
cause several diseases
Loss of habitat When macroalgae or seaweed are
decomposed by anaerobic bacteria
hydrogen sulfide (H2S)(foul odor of
rotten eggs) is released
Dissolved oxygen depletion, create
anoxic condition
Economic and financial problems for
the fishing industries
Table 1: Impact of Eutrophication

14. EUTROPHICATION EVALUATION METHODS
Fig 9: Evaluation methods applied to different waters (lakes, reservoirs, rivers and wetlands) (Zhang,2021)
There are no perfect evaluation criteria for assessing water eutrophication. Generally, the physical
and chemical evaluation parameters were used to assess water eutrophication, mainly nutrient
concentration (N and P), algal chlorophyll, water transparency and dissolved oxygen.(yang,2020)

15. TROPHIC STATE INDEX (TSI)
 Carlson trophic state index (CTSI) widely used to determine degree of eutrophication, it uses algal
biomass involving three variables namely chlorophyll-a (CA), Secchi disc depth(SD) and total
phosphorus(TP) (A. G. Devi Prasad, 2012)
 The trophic state index (TSI) of Carlson was calculated using the following formulae:
i. TSI for Chlorophyll-a (CA) = 9.81 ln (Chlorophyll-a(ug/L))+30.6
ii. TSI for Secchi depth (SD) = 60 -14.4 ln (Secchi depth(Meters))
iii. TSI for Total phosphorus (TP) = 14.42 ln (Total phosphorous (ug/l)) + 4.15
where: TSI is Carlson Trophic State Index and
ln is Natural logarithm.
 Carlson’s Trophic State Index (CTSI) =
𝑻𝑺𝑰 𝑻𝑷 +𝑻𝑺𝑰 𝑪𝑨 +𝑻𝑺𝑰(𝑺𝑫)
𝟑
Fig 11: Secchi Disk

16.  Based on the values of CTSI the lakes are classified as oligotrophic (low productive),
mesotrophic (moderately productive) and eutrophic (highly productive).
Table 2: Carlson’s trophic state index values and classification of lakes(A. G. Devi Prasad, 2012)
TSI
Values
Trophic Status Attributes
< 30 Oligotrophic Clear water, oxygen throughout the year in the hypolimnion
30-40 Oligotrophic A lake will still exhibit oligotrophy, but some shallower lakes will become anoxic
during the summer
40- 50 Mesotrophic Water moderately clear, but increasing probability of anoxia during the summer
50-60 Eutrophic Lower boundary of classical eutrophy: Decreased transparency, warm-water fisheries
only
60-70 Eutrophic Dominance of blue-green algae, algal scum probable, extensive macrophyte problems
70-80 Eutrophic Heavy algal blooms possible throughout the summer, often hypereutrophic
>80 Eutrophic Algal scum, summer fish kills, few macrophytes

17. CASE STUDY: TSI
SN
o
Author
and Year
Lake No. of
Sampling
sites
Observation
Period
Parameters Tested TSI
Value
Trophic Status
1 Shilpa et.al,
2016
Sukhna lake, Chandigarh 6 Dec 2015- May
2016 (Six
Months)
pH, DO,
Total phosphate, Nitrate,
Total suspended solid,
Transparency
- Hyper-eutrophic
2 A. G. Devi
Prasad et.al,
2012
Arakere lake,
Thaggahallilakeis lake,
Karnataka
- April.2009-Mar,
2011(Two Years)
Total Phosphorus(TP),
Chlorophyll-a, Transparency
35-53 Mesotrophic
3 Omkar et. al,
2008
Mansar lakes(J&K) - - Temperature, pH, EC,
TDS, DO, Ca, Mg,
Na, K, Alkalinity,
HCO3, Cl, So4,NO3,
PO4,F
Hardness
70-76 Eutrophic
Surinsar lakes(J&K) 61 Eutrophic
Dal lakes(J&K) 72 Hyper-eutrophic
Tsokar lakes(J&K) 86 Hyper-eutrophic
Tsomoriri lakes(J&K) 53 Eutrophic
Renuka lake (Himanchal
Pradesh)
80-85 Hyper-eutrophic
4 Ayele
et.al,2020
Tana lake, Ethiopia - - Total phosphorus,
Transparency,
Chlorophyll-a
60-70 Eutrophic
Table 3: Case Studies based on Carlson trophic state index (CTSI)

18. Fig 10: Control and remediation methods for eutrophic lakes (Zhang, 2020)
CONTROLAND REMEDIATION METHODS

19. CHEMICAL METHODS
 CuSO4 treatment is widely used as a global and empirical method to remove or control phytoplankton
blooms.
 The shallow Fairmont Lakes in Canada have been treated with CuSO4 for 58 years to reduce excessive algal
growth; the conclusion from this study is that although CuSO4 treatments are popular because of their ability
to kill and remove algae almost instantaneously, they cause immediate or cumulative harmful side effects to
many aquatic organisms (Zhang,2020)
 Advantage: Rapid, direct, simple
 Disadvantage: Costly, Incomplete, not suitable for long-term treatment, secondary pollution
Within the lake or pond Outside the lake or pond
Neutralization Activated Carbon Adsorption
Flocculation(alum) Clarification
Phosphorus precipitation Ammonia Stripping
Use of algicides and herbicides Nutrient and Ion removal
Table 4: Techniques used for restoration within and outside the lake or pond(CPCB)

20. PHYSICAL METHODS
 Physical methods are also called engineering measures
 Advantage: Simple; easy
 Disadvantage: Costly; temporary; incomplete; obvious effect in the short term; side effects
Methods Applicability Cost Advantages Ecological impact
Dilution and
flushing
Small-scale lakes High Simple;
quickly
Inconspicuous
Deep aeration Small-scale lakes; large
hypolimnion with depth
>15 m
High Direct Little impact on overall water
quality; increasing the density of
fish and zooplankton
Sediment dredging Internal load is the source
of nutrients; low settling
rate
Extremely
high
Direct Exposition of unwanted toxic substances;
destroying the sediment environment;
nutrient source cannot be completely
removed.
Mechanical algae
removal
Various lakes High Simple; safe Not removing dead algae in time is harmful
to environment
Table 5: Comparison of widely used physical methods(Zhang,2020)

21. BIOLOGICAL METHODS
 Biological methods could reinforce the interaction between microorganisms and aquatic organisms and the
self-purification ability of waters when treating aquatic pollution
 Advantage: Economical; completely; less secondary pollution; less harmful environmental impact; pollutant
concentration can be effectively reduced; sustainable
 Disadvantage: Long-period time; higher maintenance costs; suitable for relatively small watersheds
Method Detail
Microbial
Remediation
Biofilm technologies  Biofilms can be defined as communities of microorganisms attached to a surface
Biomanipulation
technologies
 This technology can improve nutrient-rich water quality and change food webs to restore the heath
of the ecosystem.
 Due to food-chain characteristics, artificially increasing or decreasing organisms could control the
number of target organisms and avoid the emergence of algal reproduction
Constructed wetlands
 Total phosphorus (TP) of 30–67% and total nitrogen (TN) of 30–52% in a hypereutrophic lake can
be reduced by wetland filtration systems
 Low cost, effective, easily operated and maintained, and environmentally friendly
Aquatic Phytoremediation
 Effective way to control, regulate, and inhibit eutrophic environments.
 Aquatic plants can effectively absorb nutrients during their growth and can remove, destroy, or
isolate harmful substances from the environment.
 Eg: Artificial Floating Bed

22. CASE STUDY: Jakkur Lake, Bengaluru
 Jakkur Lake :-
 Location: Northern part of Bengaluru near Yelahanka
 Area: 160 acres in size
 Storm water receiving: Yelahanka, Agrahara and Shivanahalli.
 Receive sewage: 12,500 households
 Project Duration:- Initial Restoration between 2009 and
2011(Govt.), further restoration 2015 onwards (Jal Poshan)
 Approach:-
 Original 10 MLD secondary STP was upgraded to 15 MLD
tertiary treatment STP
 Trees were planted along the sides of the lake for creating bird
habitation and to maintain natural flora and fauna
 The constructed wetland of 7 acres was created with wetland
species such as vetiver, water hyacinth, typhaceae, and alligator
weed. They helped in phytoremediation of the lake water
 Separate tank (kalyani) was built for idol immersion during
religious/ cultural festivities thereby preventing the pollution the
lake water Fig 11: Jakkur Lake, Bengaluru (Jamwal P., 2018)

23.  Restoration method adopted: Treated water from STP
(UASB) send through integrated system of constructed wetlands
and algal pond
 Results achieved due to restoration: Nutrient removal,
increased algal diversity
 Benefits:-
 Jakkur lake restoration project has provided livelihood
opportunity to fishermen.
 100,000 liters per day of water is drawn from a step well near
the lake for agricultural purposes
 Improved biodiversity in the surrounding area with increased
presence of local and migratory birds
 Increased land value of nearby properties
 Limitations:-
 Rural-urban conflict due to restrictions placed on activities such
as cattle grazing and bathing during the implementation period.
 Lack of awareness about the lake as some urban commons
among all beneficiaries
 Continued fund raising to meet the O&M expenses
Fig 12: (a) Before and (b) After Glimpse of the Jakkur
Lake after the Restoration Activity(NIUA)
National Institute of Urban Affair

24. REFERENCES
 Earth Materials and Health: Research Priorities for Earth Science and Public Health , The National Acadenies Press(2007)
 https://www.nrdc.org/stories/water-pollution-everything-you-need-know
 Weber C.A., “Aufbav and Vegetation der Moore Norddentschlands” Bot Jahrb, vol. 40, 1907.
 Brenda Wilmoth Lerner & K. Lee Lerner, Environmental Science: In Context, Volumes 1 & 2, Gale Cen gage learning, New York, 2009.
 William P. Cunningham & Mary Ann Cunningham, Environmental Science: A Global Concern, 10th ed. McGraw-Hill, New York, 2008.
 Smith, V.H., “Eutrophication of freshwater and marine ecosystems: a global problem”, Environ. Sci. Pollut. Res. Int. 10, 126–139, 2003.
 World Lake Vision Action Report Committee (WLVARC), International Lake Environment Committee Foundation, 2007
 Vyankatesh B. Yannawar and Arjun B. Bhosle “Cultural Eutrophication of Lonar Lake, Maharashtra, India”, International Journal of Innovation
and Applied Studies ISSN 2028-9324 Vol. 3 No. 2 June 2013 http://www.issr-journals.org/ijias/
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Himalayan Region(India)”, The 12th World Lake Conference:286-291, 2008
 Xiao-e YANG, Xiang WU, Hu-lin HAO, Zhen-li HE, “Mechanisms and assessment of water eutrophication”, Journal of Zhejiang University
SCIENCE B, ISSN 1673-1581 (Print); ISSN 1862-1783,2008
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https://doi.org/10.3390/w13020225
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25. THANK YOU