EUTROPHICATION

PRESENTED BY:NIDHI GOYAL.

WHAT IS EUTROPHICATION??

Eutrophication or more precisely hypertrophication, is the ecosystem response to the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage, to an aquatic system. One example is the "bloom" or great increase of phytoplankton in a water body as a response to increased levels of nutrients. Negative environmental effects include hypoxia, the depletion of oxygen in the water, which induces reductions in specific fish and other animal populations. Other species (such as Nomura's jellyfish in Japanese waters) may experience an increase in population that negatively affects other species.

causesEutrophication can be human-caused or natural. Untreated sewage effluent and agricultural run-off carrying fertilizers are examples of human-caused eutrophication. However, it also occurs naturally in situations where nutrients accumulate (e.g. depositional environments), or where they flow into systems on an ephemeral basis. The three main causes are:-=> LAKES AND RIVERS=> OCEAN WATERS=> TERRESTRIAL ECOSYSTEMS

LAKES AND RIVERSEutrophication generally promotes excessive plant growth

and decay, favouring simple algae and plankton over other more complicated plants, and causes a severe reduction in water quality. The addition of phosphorus increases algal growth, but not all phosphates actually feed algae.These algae assimilate the other necessary nutrients needed for plants and animals. When algae die they sink to the bottom where they are decomposed and the nutrients contained in organic matter are converted into inorganic form by bacteria. The decomposition process uses oxygen and deprives the deeper waters of oxygen which can kill fish and other organisms. Enhanced growth of aquatic vegetation or PHYTOPLANKTON and ALGAL BOOMS disrupts normal functioning of the ecosystem, causing a variety of problems such as a lack of OXYGEN needed for fish and SHELL FISH to survive. The water becomes cloudy, typically coloured a shade of green, yellow, brown, or red. Eutrophication also decreases the value of rivers, lakes, and estuaries for recreation, fishing, hunting, and aesthetic enjoyment.

OCEAN WATERSEutrophication is a common phenomenon in coastal waters. In

contrast to freshwater systems, nitrogen is more commonly the key limiting nutrient of marine waters; thus, NITROGEN levels have greater importance to understanding eutrophication problems in salt water. ESTUARIES tend to be naturally eutrophic because land-derived nutrients are concentrated where run-off enters a confined channel. Upwelling in coastal systems also promotes increased productivity by conveying deep, nutrient-rich waters to the surface, where the nutrients can be assimilated by ALGAE.

The WORLD RESOURCES INSTITUTE has identified 375 hypoxic coastal zones in the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly Japan.

DEADLY CONDITION OF MARINE ANIMALS IN

OCEAN WATER!!!!

TERRESTRIAL ECOSYSTEMSTerrestrial ecosystems are subject to similarly adverse

impacts from eutrophication. Increased nitrates in soil are frequently undesirable for plants. Many terrestrial plant species are endangered as a result of soil eutrophication, such as the majority of orchid species in Europe. Meadows, forests, and bogs are characterized by low nutrient content and slowly growing species adapted to those levels, so they can be overgrown by faster growing and more competitive species. In meadows, tall grasses that can take advantage of higher nitrogen levels may change the area so that natural species may be lost. Species-rich FENS can be overtaken by reed or reed grass species. Forest undergrowth affected by run-off from a nearby fertilized field can be turned into a nettle and bramble thicket..

ECOLOGICAL EFFECTSMany ecological effects can arise from stimulating PRIMARY

PRODUCTION, but there are three particularly troubling ecological impacts: decreased biodiversity, changes in species composition and dominance, and toxicity effects.

Increased biomass of PHYTOPLANKTONToxic or inedible phytoplankton speciesIncreases in blooms of gelatinous ZOOPLANKTONIncreased BIOMASS of BENTHIC and EPIPHYTIC ALGAEChanges in MACROPHYTE species composition and

biomassDecreases in water transparency (increased TURBIDITY)Colour, smell, and water treatment problemsDISSOLVED OXYGEN  depletion.

BEFORE AFTER

PREVENTION AND REVERSAL  While eutrophication does pose problems, humans should be aware

that natural runoff (which causes algal blooms in the wild) is common in ecosystems and should thus not reverse nutrient concentrations beyond normal levels.

EFFECTIVENESS - Cleanup measures have been mostly, but not completely, successful. Finnish phosphorus removal measures started in the mid-1970s and have targeted rivers and lakes polluted by industrial and municipal discharges. These efforts have had a 90% removal efficiency.Still, some targeted point sources did not show a decrease in runoff despite reduction efforts.

MINIMISING NONPOINT POLLUTION- Nonpoint pollution is the most difficult source of nutrients to manage. The literature suggests, though, that when these sources are controlled, eutrophication decreases. The following steps are recommended to minimize the amount of pollution that can enter aquatic ecosystems from ambiguous sources.

Riparian buffer zones- Studies show that intercepting non-point pollution between the source and the water is a successful means of prevention. RIPARIAN BUFFER ZONES are interfaces between a flowing body of water and land, and have been created near waterways in an attempt to filter pollutants; SEDIMENT and nutrients are deposited here instead of in water. Creating buffer zones near farms and roads is another possible way to prevent nutrients from traveling too far. Still, studies have shown that the effects of atmospheric nitrogen pollution can reach far past the buffer zone. This suggests that the most effective means of prevention is from the primary source.

Prevention policy- Laws regulating the discharge and TREATMENT OF SEWAGE have led to dramatic nutrient reductions to surrounding ecosystems,[but it is generally agreed that a policy regulating agricultural use of FERTILIZERS and animal waste must be imposed. In Japan the amount of nitrogen produced by livestock is adequate to serve the fertilizer needs for the agriculture industry. Thus, it is not unreasonable to command livestock owners to clean up animal waste—which when left stagnant will LEACH into ground water. Policy concerning the prevention and reduction of eutrophication can be broken down into four sectors: Technologies, public participation, economic instruments, and cooperation.