Eutrophication Process Steps

Eutrophication Process StepsEutrophication is world-wide environmental issue environmental bothers that argon related to high constriction nutrients. It is the process due to increment of alga productivity which affects adversely aquatic life and also charitable and animal wellness. It is chief(prenominal)ly influenced by homokind activities that accept agriculture and sewage effluent due to creating high amount of nutrients.The mechanism of eutrophication is briefly described in Figure 1. Large amount of nutrient excitant to the pee system remains is the main effect and high level of phytoplankton biomass results that lead to algal blossom out. Consumption of oxygen close the shadow of the weewee body is the result. The opposite personal effects of the process crumb be divided 2 categories that ar related tonutrient spreading,phytoplankton growthNitrogen and match ar two main nutrients for aquatic life. In addition, A silica is also necessary for the diatoms. Nut rient concentration in the piddle body changes during eutrophication. The nutrient is the limiting means, if it is not be available for algae develop.The sufficient factor to determine limiting factor is the ratio of northward to phosphorus compounds in the water body is an important factor for hold back mechanism. ( carry over 1). Phosphorus is gener entirelyy limiting factor for phytoplankton in fresh irrigate. For large ocean areas oft experience nitrogen as the limiting nutrient, in particular in summer. Intermediate areas such(prenominal) as river plumes are often phosphorus-limited during spring,but may turn to silica or nitrogen limitation in summer.The enrichment of water by nutrients can be of natural contrast but it is often dramatic all in ally increased by human activities. This occurs almost e very(prenominal)where in the world. There are three main sources of anthropic nutrient input runoff, erosion and leaching from fertilized hoidenish areas, and sewage f rom cities and industrial wastewater. Atmospheric deposition of nitrogen (from animal do and combustion gases) can also be important. According to the European Environment Agency, the main source of nitrogen pollutants is run-off from agricultural land, whereas most phosphorus contaminant comes from households and industry, including phosphorus- imbed detergents. The rapid increase in industrial production and in in-house consumption during the 20th century has resulted in greater volumes of nutrient-rich wastewater. Although on that point has been recently a wear anxiety of nitrogen and phosphorus in agricultural practices, saturation of soils with phosphorus can be noted in roughly areas where spreading of excessive mire from animal husbandry occurs. Nutrient removal in sewage treatment plants and promotion of phosphorus-free detergents are vital to minimize the impact of nitrogen and phosphorus pollution on Europes water bodies7.Since 1980, nitrate concentrations in majo r EUrivers take generally remained constant. There is noevidence that bring down application of nitrogen fertilizersto agricultural land has resulted in lower nitrateconcentrations in rivers. Indeed, concentrations insome regions in Europe, such as Brittany, or Poitou inFrance, and Catalunya in Spain, are sedate increasing.More detailed information on nitrates are to be foundin the companion pamphlet in this series nitrate andhealth and in the E.C. continue mentioned in (6).wastewater treatment and less phosphorus in householddetergents. Phosphorus release from industryhas also fallen sharply (Figure 3) whereas phosphorusfrom agriculture, despite a reduction in the consumptionof phosphate fertilizers in the EU, remains animportant source of phosphorus pollution.Unfortunately, due to the main type of nitrogen in theeutrophication process in summer in the coastal zone,the reduction in the discharge of phosphorus fromrivers into the sea has not been visible, except in veryspecifi c sites. In most flakes the phosphorus releasedby the sediments into the open sea is sufficient toallow eutrophication to occur, although external inputs have sharply decreased. In fact, only the Dutch coasthas benefited from the improvement of the water ofthe Rhine, everywhere else the situation is stable orhas worsened.Some activities can lead to an increase in adverseeutrophication and, although they are very specific,they should be notedAquaculture knowledge Expansion of aquaculturecontributes to eutrophication by the discharge ofunused animal food and excreta of fish into thewaterThe transportation of exotic species in general via theballasts of big ships, hepatotoxic algae, cyanobacteria andnuisance weeds can be carried from endemic areasto uncontaminated ones. In these new environmentsthey may find a lucky habitat for their diffusionand overgrowth, stimulated by nutrients availabilityReservoirs in arid lands The construction of largereservoirs to store and manage water has beentaking place all over the world. These dams are builtin prepare to allow the collection of drainage waters by huge hydrographic basins. Erosion leads tothe enrichment of the waters of these reservoirs bynutrients such as phosphorus and nitrogenFactors supporting the developmentof eutrophicationBesides nutrient inputs, the first condition supportingeutrophication development is purely physical it isthe containment (time of renewal) of the water. Thecontainment of water can be physical, such as in alake or even in a slow river that works as a chain reactor(upstream waters do not mix with downstreamwaters), or it can be dynamic.The notion of dynamic containment is mostly relevantfor marine areas. Geological features such as theshape of the bottom of the sea, the shape of theshores, physical conditions such as streams, or largeturbulent areas, and tidal movements, allow somelarge marine areas to be really contained, exhibitingvery little water renewal. This is known as dynami ccontainment. In other cases, due to tidal effects, and/or streams,some areas that would be to be prone to containmentsee their waters regularly renewed and are notcontained at all and are in that locationfore very unlikely to pose eutrophic.Other physical factors influence eutrophication ofwater bodies. Thermal stratification of stagnant waterbodies (such as lakes and reservoirs), temperatureand electric arc influence the development of aquatic algae.Increased light and temperature conditions duringspring and summer explain why eutrophication is aphenomenon that occurs mainly during these seasons.Eutrophication itself affects the penetration oflight through the water body because of the shadoweffect coming from the development of algae andother living organisms and this reduces photosynthesis in deep water layers, and aquatic grass andweeds bottom development.Main consequencesof eutrophicationThe major consequence of eutrophication concernsthe availability of oxygen. Plants, thr ough photosynthesis, begin oxygen in daylight. On the contrary, indarkness all animals and plants, as well as aerobicmicroorganisms and decomposing dead organisms,respire and consume oxygen. These two competitiveprocesses are dependent on the development of thebiomass. In the case of severe biomass accumulation,the process of oxidation of the organic matter that hasformed into sediment at the bottom of the water body impart consume all the available oxygen. Even the oxygencontained in sulphates (SO42-) will be used bysome specific bacteria. This will lead to the release ofsulphur (S2-) that will immediately capture the free oxygenstill present in the upper layers. Thus, the waterbody will loose all its oxygen and all life will disappear.This is when the very specific smell of rotten eggs, originatingmainly from sulphur, will appear.In parallel with these changes in oxygen concentrationother changes in the water environment occurChanges in algal population During eutrophication, macr oalgae, phytoplankton (diatoms, dinoflagellates,chlorophytes) and cyanobacteria, whichdepend upon nutrients, light, temperature and watermovement, will experience excessive growth. Froma public health point of view, the fact that some ofthese organisms can release toxins into the water orbe toxic themselves is important.Changes in zooplankton, fish and shellfish population Where eutrophication occurs, this part of the ecosystem is the first to demonstrate changes. Being most sensitive to oxygen availability, these species may die from oxygen limitation or from changes in the chemical composition of the water such as the excessive alkalinity that occurs during intense photosynthesis.Ammonia toxicity in fish for example is much high in alkaline waters.Effects of eutrophicationThe effects of eutrophication on the environment may, have deleterious consequences for the health of exposed animal and human populations, through various pathways. detail health risks appear when fresh water, extracted from eutrophic areas, is used for the production of drinkable water. Severe impacts can also occur during animal watering in eutrophic waters.Macroalgae, phytoplankton and cyanobacteria bloomsalga display varying degrees of complexity depending on the organization of their cells. Macroalgae, phytoplankton and cyanobacteria may colonize marine, brackish or fresh waters wherever conditions of light, temperature and nutrients are favourable. cyanobacteria have been largely studied in fresh water systems, due to their ability to proliferate, toform massive surface scums, and to produce toxins that have been implicated in animal or human poisoning.Some species of algae may also contain toxins, but incidents where fresh water algae are at the originof cases of human or animal illness have very seldom been reported.Coloured toxic tides caused by algal overgrowth have been known to personify for many centuries. In fact the Bible (Exodus, 7 20-24) states all the water of the Ni le river became red as blood and fish which were in the river died. And the river was poisoned and the Egyptians could not drink its waters.algal blooms were observed in 1638 by fishermen in north west of Iceland. Fjords were reported to be stained blood red and during the wickedness produced a kind of phosphorescence. The fishermen mind that the colours could be due to the blood of fighting whales or to some marine insects or plants (Olafsson and Palmsson, 1772). The first scientific report of domestic animals dying from poisoning as a consequence of drinking water that was affected by a blue/green algaebloom was in 1878 in lake Alexandrina, Australia.In coastal and estuarine systems, however, whereconditions are less favourable to the proliferation ofcyanobacteria, which need oligo-elements such as iron, toxic algae such as dinoflagellates have been observed and have been at the origin of healthtroubles. There is growing evidence that nutrients,especially nitrogen, favour the dur ation and frequencyof such toxic blooms, and concentrations of toxin inthe cells.Health effects linked to toxins of cyanobacteria infresh watersSome cyanobacteria have the capacity to producetoxins dangerous to human beings. Toxins can befound either free in the water where the bloom occursor bound to the algal or cyanobacterial cell. When thecells are young (during the growth phase), 70 to 90%of the toxins are cell bound, whereas when the cells Cyanobacteria have been largely studied in freshwater systems, due to their ability to proliferate, toform massive surface scums, and to produce toxinsthat have been implicated in animal or human poisoning.Some species of algae may also contain toxins,but incidents where fresh water algae are at the originof cases of human or animal illness have very seldombeen reported.Coloured toxic tides caused by algal overgrowth have been known to exist for many centuries. In fact theBible (Exodus, 7 20-24) states all the water of theNile river became r ed as blood and fish which were inthe river died. And the river was poisoned and theEgyptians could not drink its waters.Algal blooms were observed in 1638 by fishermen innorth west of Iceland. Fjords were reported to be stainedblood red and during the night produced a kind ofphosphorescence. The fishermen thought that thecolours could be due to the blood of fighting whales orto some marine insects or plants (Olafsson and Palmsson,1772). The first scientific report of domestic animalsdying from poisoning as a consequence of drinkingwater that was affected by a blue/green algaebloom was in 1878 in lake Alexandrina, Australia.In coastal and estuarine systems, however, whereconditions are less favourable to the proliferation ofcyanobacteria, which need oligo-elements such asiron, toxic algae such as dinoflagellates have beenobserved and have been at the origin of healthtroubles. There is growing evidence that nutrients,especially nitrogen, favour the duration and frequencyof such toxic blooms, and concentrations of toxin inthe cells.Health effects linked to toxins of cyanobacteria infresh watersSome cyanobacteria have the capacity to producetoxins dangerous to human beings. Toxins can befound either free in the water where the bloom occursor bound to the algal or cyanobacterial cell. When thecells are young (during the growth phase), 70 to 90%of the toxins are cell bound, whereas when the cells fresh waters. People may be exposed to toxinsthrough the consumption of contaminated drinkingwater, demand contact with fresh water or the inhalationof aerosols. Toxins induce damage in animals andhumans by acting at the molecular level and thenceaffecting cells, tissues and organs (Table 3).The nervous, back upive, respiratory and cutaneoussystems may be affected. Secondary effects can beobserved in numerous organs. Age or physiologicalconditions of the affected individual may determine theseverity of the symptoms. A variety of symptoms,depending on the toxins implicat ed, are observedsuch as fatigue, headache, diarrhoea, vomiting, sorethroat, febrility and skin irritations. Cyanotoxins can be classified into three groups Hepatotoxins.These are the most frequently observed cyanotoxins.Experiments using mice indicate that they cause liver-coloredinjury and can lead to death from liver haemorrhageand cardiac failure within a few hours of exposure atacute doses. Chronic exposure induces liver injuryand promotes the growth of tumours.Questions remain concerning the effects of repeatedexposures to low levels of toxins. Animal experimentshave shown liver injury from repeated oral exposure tomicrocystins, the most frequently observed cyanotoxins.It is thought that the high prevalence13 of livercancer observed in some areas of China could be dueto the posture of microcystins in water supplies. Neurotoxins.These are generally less common and act on the nervoussystem. In mice and aquatic birds, they causerapid death by respiratory arrest, sometimes occurr ingin a few minutes. Dermatotoxins.These induce irritant and allergenic replys in tissuesby simple contact.The global toxicity of a cyanobacterial proliferation isnot constant in time or space, making it difficult toassess the health threat although some acute poisoningshave led to death (Tables 3 and 4).The release of cyanotoxins in water has been at theorigin of several outbreaks affecting animal or humanhealth (Case studies p. f12). About 75% of cyanobacterialblooms are accompanied by toxin production.The presence of cyanobacterial toxins after potabilizationtreatment represents a health threat for patientsundergoing renal dialysis treatment.Monitoring of eutrophicationMonitoring is useful if it is performed for a purpose. The main reasons for proctoring a water body foreutrophication are To prevent the occurence of eutrophication Early warning purposes. Public health authoritiesneed to know when eutrophication is likely to start inorder to allow them to implement preventive act ions To know the level of development of the process, and have a precise picture of the tone of voice of the water.This is mostly relevant for water companies, whichhave to deal with eutrophic waters Research.The reality is that monitoring systems are often multipurpose.Monitoring and focussingof cyanobacterial growth in fresh watersfor public health purposesChorus and Bartram (1999) have proposed the followingmonitoring and management scheme to watertreatment plant operators and managers as an alertlevel framework. It provides a graduated response tothe onset and progress of a cyanobacteria bloom.This tool initially comes from Australia. Three responselevels are defined Vigilance Level is defined by the sleuthing of one colony, or five filaments, of a cyanobacterium in a 1 mlwater sample. When the Vigilance Level is exceeded,it is recommended that the affected water body issampled more(prenominal) frequently at least once a week, sothat potentially rapid changes in cyanobacter ia biomasscan be monitored. Alert Level 1 is initiated when 2,000 cyanobacterialcells per ml or 0.2 mm3/l biovolume23 or 1 g/l chlorophyll- a24 are detected. Alert Level 1 conditionrequires an assessment to be made of the total toxinconcentration in the raw water. A consultation shouldbe held with the health authorities for on-goingassessment of the status of the bloom and of the suitabilityof tempered water for human consumption. Monitoringshould be conducted at least once per week. It may also be appropriate at this time to issue advisory notices to the public through the media or other means. Government departments or interested authorities or those with legal responsibilities should also be contacted, as should organizations that treat or care for members of the public with special needs. Alert Level 2 is initiated when 100,000 cells per ml or 10-mm3/l biovolume or 50 g/l chlorophyll-a are detected, with the presence of toxins confirmed by chemical or bioassay techniques. This density of cells corresponds to an established, toxic bloom with high biomass and possibly also localized scums. In this situation there is a need for effective water treatment systems and an assessment of the performance of the system. Hydro-physical measures to reduce cyanobacteria growth may still be attempted. If efficient water treatments are not available (see technical annex), a contingency water supply plan should be activated. In extreme situations, safe drinking water should be supplied to consumers in tanks and bottles. Media releases and contact with consumers should be undertaken via mail of leaflets informing that water may present danger for human consumption but is still fit for the purposes of washing, laundry and toilet flushing.National water forest monitoring programsFew national water quality monitoring programmes include parameters which indicate eutrophication or a risk of algal or cyanobacterial overgrowth. In Europe, North America, Japan and Australia, loc al monitoring plans which check the occurrence of toxic species in areas where shellfish or fish are consumed, are implemented. This is based on sampling at strategic points and epitome of phytoplankton and/or shellfish. The frequency of sampling generally depends on the sea- son. Table 6 summarizes the monitoring systems in some EU Member States. They only allow the monitoring of toxic blooms, which are only a part of the eutrophication consequences.Technologies such as satellite imaging can be used to monitor large water bodies. The same technique can be applied to monitor the extent of high chlorophyll-a concentrations reflecting the phytoplankton biomass of the upper layers of the eutrophic area.Possible parameters used for monitoring purposesAccording to the definition of eutrophication, it is clear that formulae such as an increase of x grams of bottom macrophytes per squarely meter or y micrograms chlorophyll-a per litre are not suitable to define a threshold, which, when e xceeded, will describe eutrophication.Such unique parameter does not exist. Moreover, in order to define the magnitude of eutrophication, two measurements are required That of the system in its reference conditions, and in its current or predicted future condition. As baseline data for a site is the exception rather than the rule, this makes it difficult to test eutrophication using a case-by-caseapproach. Nevertheless, as the first signs of adverse eutrophication is a decrease in the oxygen concentration in the lower layers of the water body of stagnant waters, and an increase in pH due to photosynthesis (CO2 depletion), these parameters, together with use up microscopic observations, are likely to be the only ones that can abet forecast the likelihood of the start of such a process as spacious as a model integrating physical conditions, nutrient inputs and biological effects has not been locally validated. Prevention25,26The causes that drive eutrophication are multiple and th e mechanisms involved are complex. Several elements should be considered in order to assess the possible actions aimed at counteracting nutrient enrichment of water supplies. The use of computerised models now allows a better understanding of the subroutine of each factor, and forecasting the efficiency of various curative and preventive measures. The best way to avoid eutrophication is to try to disrupt those mechanisms that are under human control this clearly means to reduce the input of nutrients into the water basins. Such a control unfortunately does not have a linear effect on the eutrophication intensity. Integrated management should comprise Identification of all nutrient sources. Such information can be acquired by studies of the catchment area of the water supply. Knowledge of industrial activities, discharge practices and localization, as well as agricultural practices (fertilizer contribution/plant use and localization of crops) is necessary in order to plan and imple ment actions aiming at limiting the nutrient enrichment of water.The identification of sewage discharge points, agricultural practices, the nature of the soil, the vegetation, and the interaction between the soil and the water can be of great help in knowing which areas should be targeted. Knowledge of the hydrodynamics of the water body, particularly the way nutrients are transported, and of the vulnerability of the aquifer, will allow determination of the ways by which the water is enriched with nutrients.Anthropogenic nutrient point sources such as nontreated industrial and domestic wastewater discharge can be minimized by self-opinionated use of wastewater treatments. In sensitive aeras, industries and local authorities should control the level of nutrients in the treated wastewater by the use of specific denitrification or phosphorus removal treatments.Diffuse anthropogenic nutrient sources can be controlled by soil conservation techniques and fertilizer restrictions.Knowledge of the agronomic balance (ratio of fertilizer contribution to plant use) is very relevant to optimize the fertilization practice and to limit the loss of nutrients. Diffuse nutrient losses will be reduced by implementation at farm level of goodly practices suchas Fertilization balance, for nitrogen and phosphorus, e.g. adequation of nutrients supply to the needs of the crop with reasonable evaluate yields, taking into account soil and atmospheric N supply. Regular soil nutrients analysis, fertilization plans and registers at plot level. Sufficient scatter storage capacities, for spreading of manure at appropriate periods. Green cover of soils during winter, use of catchcrops in crop rotations. Unfertilized grass buffer strips (or broad hedges) along watercourses and ditches. Promotion of permanent grassland, rather than temporary forage crops. Prevention of erosion of sloping soils. Precise irrigation management (e.g. drip irrigation, fertilisation, soil moisture control).In coa stal areas, improvement in the dispersion of nutrients, either through the multiplication of discharge points or through the changing of their localization, can help to avoid localized high levels of nutrients.Reuse and recycling, in aquaculture and agriculture, of waters rich in nutrients can be optimized in order to avoid discharge into the water body and direct consumption of the nutrients by the local plant and fauna.Water resources are environmental assets and therefore have a price. There are market-based methods to estimate costs and benefits, and these make it possible to use cost- benefit analysis as a useful tool to assess the economic effects of abatement of eutrophication or other pollution problems. Benefits range from higher quality drinking water and reduced health risks (Photo 29) to improved recreational uses (Photo 30). The effects on human health from the lack of sanitation and the chronic effects of toxic algal blooms are two of the many indirect effects resulti ng from eutrophication. Numerous cost-benefit analyses of pollution abatement have clearly demonstrated that the total costs to society of no pollution reduction is much higher than at least a reasonable pollution reduction. Consequently, it is necessary to examine the prevention of pollution and restoration of water quality in lakes and reservoirs from an economic standpoint. The result of such examinations should be applied to assess effluent charges and green taxes. International experience shows that these economic instruments are sanely effective in improving water quality and solving related water pollution problems. Thus, effective planning and management of lakes and reservoirs depends not only on a sound understanding of these water-bodies as ecological systems but also of their value to people as recreational areas and water resources.In the past, several management strategies were developed and applied to solve problems of decreasing surface and groundwater quality. Thes e were often a response to acute critical situations resulting in increased costs of water. The demand for good quality fresh water was only solved partially and locally this was because too few resources were allocated too late to solve the problems. Early prevention is by far the cheapest method to avoid later pollution.Eutrophication ManagementRecognizing that the specific needs of policy-makers and administrators are usually different from those of the strictly technical audience, the primary purpose of this digest is to provide quantitative tools for assessing the state of eutrophication of lakes and reservoirs to provide a framework for developing cost-effective eutrophication management strategies to provide a basis upon which strategies can be tailor-made for each specific case according to the physical, social, institutional, regulatory and economic characteristics of the local area or region and to provide specific technical guidance and case studies regarding the effecti ve managementof eutrophication. The approach presented in this document (Figure 1) also is sufficiently general that it can be applied, with relative little modification, to the assessment of other environmental problems and to the development of effective management strategies for such problems.An approach for achieving the basic objectives stated above consists of the following components, applied approximately in the order presented identify eutrophication problem and establish management goals assess the extent of information available about the lake/reservoir identify available options for management of eutrophication analyze all costs and expect benefits of alternative management/control options analyze adequacy of existing institutional and regulatory framework for implementing alternative management strategies select desired control outline and distribute summary to interested parties prior to implementation and provide periodic progress reports on control programme to publ ic and other interested parties. appellative of bad (unacceptable) versus good (acceptable) water quality in this digest is based on the specific intended use or uses of the water resource.That is, water quality management goals for a lake or reservoir should be a function of the major purpose(s) for which the water is to be used.Obviously, there are water quality conditions to be avoided because of their interference with water uses. Ideally, for example, a lake or reservoir used as a drinking water supply should have water quality as close to an oligotrophy state as possible, since this would insure that only a minimum amount of pre-treatment would be necessary to yield a water suitable for human consumption. For such a waterbody, the content of phytoplankton (and their metabolic products) in the water should be as low as possible to facilitate this goal. Further, if the water is taken from the bottom waters of a lake during the summer (usually the period of maximum algal growth), it should be free of interferring substances resulting from decomposition of dead algal cells. Eutrophic lakes and reservoirs also could be used as a drinking water supply. However, extensive pre-treatment would be necessary before the water was suitable for human consumption.Some water uses may require no treatment at all, regardless of the existing water quality. Examples are fire-fighting purposes and the transport of commercial goods by ship. Further, in areas with extremely limited water resources, virtually all of the water may be used for various purposes (with or without treatment), regardless of its quality. Therefore, although humans can use water exhibiting a range of water quality, there is a desirable or optimal water quality for virtually any type of water usage. Though it is not quantitative in nature, a summary of intended water uses and the optimal versus minimally-acceptable trophic state for such uses is provided in Table 3. In addition, an example of the values of several commonly mensural water quality parameters corresponding to different trophic conditions, based on the international eutrophication study of the Organization for Economic Cooperation and Development (1982), is provided in Table 4. Thus, it is possible to identify acceptable or optimal water quality for given water uses.Given these factors, a prudent approach in setting eutrophication management goals is to determine the minimum water quality and trophic conditions acceptable for the primary use or uses of the lake or reservoir (Table 1), and attempt to manage the water body so that these conditions are achieved. In a given situation, if the primary use or uses of a waterbody is hindered by existing water quality, or else requires water quality or trophic conditions not being met in the waterbody, this signals the need for remedial or control programmes to achieve the necessary in-lake conditions.21 the problem?The governmental consumptionIt is recognized that a range of different forms of government, as well as economic conditions, exist around the world. Consequently it is difficult to provide general guidelines regarding the role of the government in environmental protection efforts that will cover all possible situations. However, virtually all nations also contain some type of complaisant service infrastructure which, if properly used, can be an effective instrument with which to address governmental concerns. Even so, as noted earlier, not all