Eutrophication Final

8/2/2019 Eutrophication Final

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INTRODUCTION The word eutrophic comes from the Greek word eutrophos

meaning well-fed.

Eutrophication is the process of excessive nutrient enrichment ofwaters that typically results in problems associated withmacrophyte , algal or cyano bacterial(blue-greenalgae),Nodularia spumigena growth.

Natural eutrophication is the process by which lakesgradually age and become more productive due toenrichment with nutrients (Nitrogen and Phosphorus). Itnormally takes thousands of years to progress. However,humans, through their various cultural activities, havegreatly accelerated this process in thousands of lakes aroundthe globe.


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NATURAL EUTROPHICATION Lakes originate as oligotrophic having limited

quantities of nutrients depending upon their modeof formation and composition of originalsediments.

At this stage lakes have only autochonousnutrients which recycle in the absence of anyoutside supply. All the biological production is

completely decomposed after death.

As the nutrients from outside start coming in, theprocess of eutrophication sets in.


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The buildup of nutrients through this slow mode of entrygradually starts increasing the growth of algae.[9]

When algae die and decompose, locked nutrients aremade available to the algal growth.

During each cycle, nutrients are progressively increased

in the water body.

With advancement of eutrophication, production-decomposition equilibrium is lost and an ever increasingorganic matter is introduced in the lakes which ultimately

gets deposited at the bottom.

Slowly, the thickness of the bottom sediments increaseswith time, leading to the formation of marshes and finallyextinction of the water body in the long run.


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ACCELERATED

EUTROPHICATION

The process of eutrophication is greatlyaugmented by increased supply of nutrientsthrough various human activities.

This triggers the algal growth at a much fasterrate, thus, increasing the speed of eutrophication,which otherwise would have been a slow naturalphenomenon.


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ACCELERATED

EUTROPHICATION

The process of eutrophication is greatlyaugmented by increased supply of nutrientsthrough various human activities.

This triggers the algal growth at a much fasterrate, thus, increasing the speed of eutrophication,which otherwise would have been a slow naturalphenomenon.


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Based on the levels of nutrient supplied to it , alake is classified according to the trophic state

Oligotrophic

low in nutrients. Mesotrophic intermediate nutrients.

Eutrophic high in nutrients.


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Sources of Eutrophication

POINT SOURCES: In point sources nutrient wastetravels directly from source to water. Eg.Factories having waste discharge pipes leadingdirectly to a water body can be classified as apoint source. Point sources are relatively easy toregulate. They include:

1. Wastewater effluent (municipal and industrial)

2. Runoff from waste disposal system

3. Runoff and infiltration from animal feedlots

4. Runoff from mines, oil fields, unseweredindustrial site

5. Overflows of storm and sanitary sewers [10]6. Runoff from construction sites


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NON- POINT SOURCES: these are ill-defined

and diffuse. Thsy are difficult to regulate and varyspatially and temporally (with season,

precipatation and other irregular events). Theseinclude:

Runoff from agriculture and irrigation

Runoff from pasture and range

Septic tank leachate

Runoff from construction sites< 20,000 sq. mt.

Runoff from abandoned mines

Atmospheric deposition over a water surface

Other land activities generating contaminants.


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FACTORS AFFECTING

EUTROPHICATION

Land usage : Human alterations & disturbance

Differences in land use patterns

Higher nutrients load correlated with

increased urban & agricultural land

usage Efficiency of chemical cycling &

hydrologic processes

In urban streams: impervious surfaces

decreased contact time between the

runoff water & the soil Factor affecting nutrient & sediment

loads: land form, land use intensity,

material usage


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Geology & physiography of the catchmentarea:[4,7]

nutrient supplied to a water body is inversely proportionalto the volume of the lake

composition of the underlying rock

structure & the type of soil

nutrients input is greater in watersheds with steeper slope

Factors related to water bodies characteristics of the water body modify the effect of

causative factors

affect the productivity indirectly:- distribution, availability& utilization of the nutrient inputs


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Climate Annual energy & water input

Hydrology of the catchment area

Flushing rate of the water body

Length of growing season

Direction & velocity of the wind

Quantity of precipitation

The type & patterns of climate


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Problems caused by

eutrophication

Species diversity decreases and the dominant biota changes Plant and animal biomass increase Turbidity increases Rate of sedimentation increases, shortening the lifespan of the

lake.

Anoxic conditions may develop Increased vegetation may impede water flow and navigation Treatment of drinking water may be difficult and supply can have

an unacceptable taste or odour

Decrease in water transparency

Disssolved oxygen depletion [1] Fish kills

Decrease in perceived aesthetic value of water body


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CONTROL OF

EUTROPHICATION Removing nutrients like nitrogen and

phosphorous before discharging the sewage intowater bodies i.e. better wastewatertreatment.[8,9]

Elimination of phosphate from detergents toreduce the contribution of phosphorous indomestic wastewater being discharged into waterbodies. [2]

Effective disposal of organic matter as sludge andremoval of the algal blooms by dredging.[3]

Applying solutions of chemicals like coppersulphate (an algicide) and chlorine on the surfaceof the water bodies susceptible to

eutrophication.[5]


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References1.Miguez M.G., Mascarenhas F. (2009),Eutrophication of fresh water and

marine ecosystems, ASCE, volume 135, pp. 100-109

2. Wurbs R.A. (2002), A flushing system to clean up coastal lagoons, ASCE,volume 7, pp. 35-423. Siviglia A., Stocchino A., Colombini M. (2009), Aerating circulation, ASCE4. Yeh C.H., Labadie J.W. (1997), Prediction of nutrient concentration in urbanstorm water, ASCE, volume123, pp.336-3435. Arega F., Lee J.H.W, Tang H (2008), Retention of sediments and nutrientloads with peak runoff control, ASCE, volume 134, pp.23-336. Guo Y. (2001), Nutrient loading estimates for lakes, ASCE, volume 6, pp472-4797. Ponce V.M., Osmolski Z, Smutzer D. (1985), Life-cycle assessment oftitanium dioxide coatings, ASCE, volume 113, pp. 1467-14718. Horn D.R. (1987), Phosphorous removal from lake water by combineddosage of ferrous iron and diatomite, ASCE, volume 113, pp.283-2929. Slutzman J.E., Smith J.A. (2006),Sedimantary phosphorous and arsenicinactivation in alum treated lake, ASCE, volume 11, pp432-44110. Islam M.M., Sado K.(1997), Sediment oxygen demand and nutrient fluxesfor tropical reservoir in Singapore, volume 7, pp 346-355


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THANK YOU!!!

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Eutrophication Final