Abr 2012-3-7-3101-3109


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Abr 2012-3-7-3101-3109

  1. 1. www.scholarsresearchlibrary.comtAvailable online aScholars Research LibraryAnnals of Biological Research, 2012, 3 (7):3101-3109(http://scholarsresearchlibrary.com/archive.html)ISSN 0976-1233CODEN (USA): ABRNBW3101Scholars Research LibrarySoil Pollution Control Management Techniques and MethodsPeyman Pour-Nasr Khakbaz1, Saeid Mahdeloei*2, Aliakbar heidari31Department of Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran2Young Researchers Club, Science and Research Branch, Islamic Azad University, Tehran, Iran3Department of Horticulture, Science and Research Branch, Islamic Azad University, Tehran, Iran_____________________________________________________________________________________________ABSTRACTEntrance of materials, biological organisms and energy into the soil will cause changes in soil quality andeventually, this problem will remove soil from its natural state. When condition of soil is changed as a result ofhuman activities and/or if the soil cannot be used anymore, it means that the soil is contaminated in this case.Pollution is defined as the chemical or natural materials, entered into the soil, which has caused interference in thenatural balance of the soil. Materials and particles aggregated during the long time in the soil are considered as animportant factor in pollution of shallow underground waters. Desertification is the other effects of soil pollution,because, soil pollution will cause loss of vegetation and reduce plants’ growth and development, details of whichwill erode soil and create desertification gradually. From among the pollutions which threaten the environment, soilpollution is considered as the most important type of the pollution due to its widespread detrimental effects both forthe environment and human being. But on the other hand, development and progress of human communities isimpossible without using chemicals. With its features like condensation and acceleration of polymerization,protection of organic molecules from disposition by the ultraviolet radiation, giving intermediate metal ions andphosphates, holding down osmotic potential of water, providing a relatively high ability to absorb the major cationsin the same proportion with compounds of plants and animals and also providing rich solution in cations, the soilprovides preliminary background for evolution, genesis and survival of life in the nature. The risk of soil pollution isnot less than the risk of air pollution, but since this pollution is not tangible, it is less taken into consideration.The soil pollution is called to any type of change in feature of constituent components of the soil in a way that it isimpossible to use the soil. Soil pollution will cause loss of vegetation and decrease growth and development of theplants and ultimately lead to the soil erosion and desertification. Presently, there is a deterrent factor entitled “SoilRule” in European countries to prevent soil from being contaminated which has caused to prevent increasedcontamination of soil to a great extent. The said Rule has recently been put forward in our country and we expect itto run properly.Keywords: Technique and Method, Pollution, Soil, Waste, Control, Phytoremediation._____________________________________________________________________________________________INTRODUCTIONSoil is one of the important and valuable resources of the nature. Life and living on the earth would be impossiblewithout healthy soil. 95% of human food is derived from the earth. Making plan for having healthy and productivesoil is essential to human survival. Entrance of materials, biological organisms or energy into the soil will causechanges in soil quality. This problem causes soil to remove from its natural state.The soil is composed of two parts. 1- Soil Living Part, 2- Soil Dead Part
  2. 2. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3102Scholars Research LibraryThe dead part of the soil includes weathered rocks and minerals which are obtained from the decay of plants andanimals, which is called organic matter or humus, and water and air are categorized in this part. But the live soil isthe soil which enjoys small animals like insects and worms and plants, fungi, bacteria and other microbes are grownin the live soil [2].The soil is composed of 50% of organic and inorganic matters, and 50% of air and water which fills existing vacantspaces of the soil and keeps live organisms of the soil.The Law on preventing contamination of Iran’s soils reiterates that: “If a unit causes soil pollution of its surroundingareas, it is sentenced 6 months to 2 years imprisonment at the first stage and then payment of the cash fines at thenext stages. Of course, it has been tried to use less cash fines in this regard, because, determining cash fine rate is adifficult task due to the vastness of the pollution and extent of pollution can not be usually identified exactly. Also,the polluting unit is duty bound to employ consultant and contractor for removal of the pollution in the region. Boththe consultant and contractor should continue their activity as long as the soil of the region reaches to its standardlevel and the danger does not threaten the region as well [9].Soil PollutionThe soil will be polluted as a result of different human activities. Most of these pollutions are caused by vehicleaccident which moves contaminants.The other pollutants, which cause soil pollution, include cars, trucks and airplanes that do not move the waste;rather, they carry materials like fuel which can cause soil pollution as a result of pouring and emitting them from thevehicle.The factors like human activities will also pollute the soil. Dumping of toxic substances like different types ofsolvents, colored materials and detergents will extend earth and soil pollution [1].Role of Soil PurificationSoils are considered as purifications of the nature. Moreover supplying food, soil has purification property as well.This soil property is obtained as a result of their physical properties (water infiltration operation from pores), theirchemical properties (surface absorption and evaporation) and their biological properties (decomposition andcorruption of organic matters).Several chemical and physical processes are involved in formation of different types of soil. During the chemicalprocesses, organic and inorganic matters face decomposition and change. Meanwhile, physical processes generatethe moved materials and different horizons of the soil. Soil is the origin of the universe and also human heritage forthe future and posterity [5].The knowledge of pedology (soil science) studies the soil as a very complex natural compound which has createdfrom physical and biochemical weathering.A pedologist studies the soil as a composition and does not consider its applications.Pedology helps us determine the best possible application for the soils of different areas, protect it and increase itsquality as well [7].Sources of Soil PollutantWhen the balance is entangled between constituent components and elements of the soil due to the human excess orintervention, we had to wait outbreak of many disorders. Addition of excessive chemical fertilizers to the soil inorder to increase the product may cause difficulty in task of soil purification. Also, the drainage water, containinghigh chemical fertilizer compounds, can cause salinity of the soil in somewhere else like excessive irrigation withthe inappropriate quality water.The heavy and rare elements are of the pollutants which are placed on the soil absorbent complex surfaces withadding to the soil in different ways especially discharging wastewater and will cause chemical pollution of the soil.Then, the polluted soil is entered human and animal food chain and consequently, will bring about unpleasant healthhazards in the environment [3].
  3. 3. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3103Scholars Research LibraryThe researchers consider the main resources of these pollutants as parent materials of these elements which isreleased as a result of weathering effect and is entered the soil as well as external resources which are entered thesoil in different methods.Fall of heavy elements and radioactive from the atmosphere to the earth, including combustion of fossil fuels,exhaust of automobiles, smelting of metals, chemical industries, burning of wastes and garbage, radioisotopes as aresult of reactor accidents and vast firing, is only one way of chemical contamination of the soil [1].The chemicals used in agriculture, discharge of wastewaters, abandoned industrial sites like gas factories, electricalindustries, tanneries, or leather manufacturing industries and even sports and recreational activities like shooting areof the cases affecting soil pollution. Among all chemical pollutants, it seems that rare elements and heavy metalshave had specific ecological, biological and/or health effects on the environment of organisms living on the earth.Resistance and reliability of heavy metals in soil is very long than other pollutants while soil pollution by the heavymetals is relatively permanent. Nowadays, active mines, consumption of fossil fuels, agricultural pesticides andfertilizers are considered as the most important factors of biosphere pollution to these elements [8].Nowadays, among pollutant resources, the followings are considered as the most important factors of biospherepollution:- Active mines (industrial pollution)- Consumption of fossil fuels (oil pollutions)- Agricultural fertilizers and pesticidesIn continuation, these pollutants are described briefly.1) Presently, we are facing severe soil and water resources’ pollution due to the excessive production of waste,wrong collecting and incomplete recycling of household, industrial, hospital waste, industrial wastewaters, urbanwastewater, construction wastes and accumulation of waste at the margin of the cities.2) Motor-pool vehicles pollute the air with producing carbon monoxide on one hand and their oil, rubber files andbrake pads, containing asbestos, destroy soil resources and environment on the other hand.3) Heavy metals are one of the problems of sewages and industrial wastes which enter the soil. The heavy metalslike lead, cadmium, selenium, etc. which are stored in soil colloids are very dangerous and will incur irreparablelosses while entering the food chain.4) Acid rains are one of the cases of soil pollution which is observed as a result of pollution and smoke of factoriesin industrial and densely-populated cities. Among other factors of soil pollutions, the acid rain is considered as theworst type of pollution, because, acid rain will eradicate forest lushes at the first step and also contaminate waterresources at the second step.5) Pollution caused by agricultural activities6) Oil pollutions7) Industrial pollutions caused by factories and mines.Industrial PollutionIn most cities, we are witnessing that wastewaters of factories are poured into the rivers. Moreover contaminatingsurface waters and soil pollution, factories’ waste will contaminate underground resources as well. Smoke andpollutants which are emitted in the form of toxic fumes and gas from giant chimneys of the factories, moreovercontaminating air of cities and creating respiratory problems for human beings, they will also form the acid rains.Most pollution of soil resources are observed at surrounding areas of the refineries [2].Resistance and stability of the heavy elements in soil is very long than other pollutants and soil pollution by theheavy metals is relatively permanent. The heavy metals include lead, cadmium, silver and mercury which theirdetrimental effects have been proven on the living creatures and have repeatedly caused environmental incidents.Some of these detrimental effects of the heavy metals include as follows: disorder of biological activities of the soil,toxic effects on plants and harmful effects on human being as a result of entrance of materials to the food chain [6].WastesWaste is one of the most important resources of contamination of soils. The wastes can infiltrate inside the earth andcontaminate water resources as well. Almost all advanced countries call waste as "Dirty Gold" which creates valueadded to the waste with recycling and producing compost. Hospital waste is one of the most important anddangerous urban wastes. Some part of body tissue of a patient, needles contaminated to the dangerous diseases,surgical blades containing AIDS disease, etc. are of the wastes which are collected from hospital along with
  4. 4. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3104Scholars Research Libraryhundreds of thousand tons of ordinary waste. Disposal of hospital wastes contaminates underground waters as well[11].Effect of Detergents in SoilExistence of detergents in sewage will increase soil permeability and microorganisms and even molecules, whichcannot pass ordinarily from soil filters, will able to pass from pores of consecutive and different layers of soil in thepresence of detergents and can cause microbial contamination of the waters which are placed in a relatively highdistance to the ground level [5].Agricultural PollutionExcessive use of agricultural fertilizers and pesticides, antibiotics and hormones in livestock and irrigating farmswith contaminated wastewaters are agricultural factors affecting soil pollution. Cancer, nervous, respiratory and skindiseases are of the long-term effects of pesticides on human. Pesticides are entered the soil in different ways whichinclude: through direct application of them in soil, through spraying and return of pesticides particles suspended inthe air directly to the ground, toxins absorbed on surface of soil particles suspended in air and their sitting on theground and plant residues that are added to the soil and the toxins absorbed by the soil organisms (non-lenticular).Chemical fertilizers change properties of the soil i.e. lessen soil permeability to the air and water. Generally,chemical fertilizers harden soils. Chemical pesticides create soil pollution as well. A number of pests especiallyinsects are strengthened against consumable pesticides. Under such circumstances, we have to either increase thenumber of spraying or boost concentration of toxins. These toxins are not decomposed easily and will remain in soilfor many years [14].Oil PollutionIt is for a long time that oil materials and its derivatives cause soil pollution as a result of transportation or storage.Oil pollution is an inevitable outcome as a result of rapid population growth and industrialization process, based onwhich, soil pollution can be observed by oil hydrocarbon materials vastly around exploration and refininginstallations typically via transfer of these materials. In addition to the direct emission of these pollutants, dusts ofburning gases along with oil have managed to add toxic and harmful substances to the soils of the region for longyears. If more oil materials are penetrated into the more depth of soil, removing its pollution is a difficult task andwill cost dearly [4].Environmental Cleanup CostsUntil 2000, the United States of America has spent approx. 2% of its gross national income to the cleaning upenvironment and controlling pollution. The said rate accounts for 50% of the amount which we pay for our garmentand is 33% of the amount which is paid to the military forces. After 2000, the said amount has been increased morethan 8.2 percent of its gross national product (GNP).Except the Netherlands, no any other country can be found to invest the said rate on the environmental problems[10].Soil Pollution in IranBased on the statistics, a little percentage of industrial and household wastewater in the country is treated and majorpart of the industrial and household sewages of the country is entered the environment as raw which will follow soilpollution and contamination of underground waters as well. Increased rate of nitrate in water of wells is a clearevidence of the said claim. Acid rain is one of the cases of soil pollution which is observed less in our country.Severe opposition to set up a coke mfg. factory in Savadkouh is one of the measures taken by the Department of theEnvironment (DoE) to prevent acid rain from falling. The pollution atlas of the Iranian soils is at preparation stage.If the map is prepared, an exact statistics on degree of soil pollution in the country will be obtained. To date, thefollowing areas have been reported as the most polluted areas in Iran: Isfahan Province, Southern Tehran, Assaluyehin Bushehr, land areas around Sarcheshmeh Copper Mine, Sistan-Baluchestan Province, and a major part ofKhuzestan [7].Soil Pollution in TehranPollutions caused by oil leakage from oil transmission pipelines in southern Tehran have been reported as one of thesoil pollutants in Tehran. Using agricultural pesticides across Tehran Province is regarded as the other soilpollutants.Fall of acid rains, due to the existence of high pollution in Tehran, is the other cases of soil contaminant in this city[12].
  5. 5. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3105Scholars Research LibrarySoil Pollution Control TechniquesSoils are considered as purification of the nature. Moreover supplying food, soils have also purification property.This soil property is caused by their physical properties (water permeability operation from pores), their chemicalproperties (surface absorption and evaporation) and their biological properties (decomposition and corruption oforganic matters) [3].1. Controlling Oil Pollutions in SoilOil materials and their derivatives may cause soil pollution as a result of transport or storage. If more oil materialsare penetrated into the more depth of soil, removing its pollution will be more difficult. Some bacteria andmicroorganisms in soil can cause decomposition of oil materials which will be explained in the topic entitled"Elimination of Pollution Biologically".Hereunder are regarded as the ways to control effects of oil pollution:1. Preventing oil from spreading widely,2. Improve the soil ventilation through plowing and mixing,3. Increasing food nutrients to the soil like nitrogen and phosphor,4. Combining soil with microorganisms which decompose oil materials [13].2. Controlling Pollutions Caused by Waste in soilWaste is one of the most important sources of soil contamination. Waste can penetrates into the ground and pollutethe water resources as well.Methods of waste disposal include: 1- dumping, incinerating and recyclingIn dumping method, areas are created as “Land field” and garbage or waste is dumped there. In this method, waste isdumped below the ground level, aimed at not to be observed from ground surface but the said method createssubsequent problems. These problems include: pollution of water resources, producing bad odor and poisonousmethane gas which provides fire danger, accumulation of harmful insects and organisms [9].To control soil pollution caused by the waste, the following techniques are recommended:1. Application of effective technology for dumping waste like compressing and covering of openings and holes,2. Dumping waste higher than the highest underground water levels,3. Creating impenetrable layers in building of land fields4. Creating drainage system for the collection of leachates5. Using the gases produced in land fields.In incineration method, all wastes are collected at a place away from residing place and then, they are put on fire.Incineration method is one of the worst methods of waste disposal, because, incineration will produce verypoisonous gases which will pollute the air and incur irreparable loss to the environment as well. After incineration,ash of waste is remained and will create visual pollution.Recycling is the best method of waste disposal. With storing some waste and reusing them, human can greatlycontribute reduction of waste. In this method, not only creation of more waste is prevented, but also, more cost willalso be saved remarkably [6].3.Controlling Pollution Caused by Industrial Activities in SoilThis method includes all the pollutants which are entered the soil by the factories. These wastes include as follows:Wastes produced by steel industries and power plants, wastes of chemical industries, wastes of steel mfg. industries,wastes of metalworking industries, wastes of oil industries (extraction and refining), wastes of wood, cellulose andpaper mfg. industries, wastes of leather production industries as well as waste of food industries.Accumulation of heavy metals in soil is the major discussion of the industrial pollutions. These metals include lead,cadmium, silver and mercury which their harmful effects have been proven on the living organisms and haverepeatedly caused environmental disasters [8].Some of these effects are as follows:- Disturbance of biological activities of soil,- Toxic effects on plants,- Harmful effects on human being as a result of entrance of materials to the food chain
  6. 6. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3106Scholars Research LibraryThere are three main methods for soil decontamination from industrial wastes as follows:1.Soil can be excavated up to the specified depth and the excavated soil can be taken away from the region and then,it can be restored.2.The soil can be restored at the same area.3.Keeping soil in the area is the other method. Under such circumstances, auxiliaries are added to the soil to preventspread of infection to the plants, animals and human.Usually, a large plastic is drawn on the soil to prevent spread of soil pollution, to prevent water from penetrating intothe soil and to prevent spread of pollution to the other regions [2].The soil restoration methods includes as followsUsing water to remove pollutants from the soil, using chemical and aerial solvents, eliminating pollutants withincineration, helping natural organisms for breaking down atoms of pollutants, adding materials to the soil forprotecting it and preventing spread of pollution to the other regions [11].Role of Plants in Controlling and Decreasing Soil Pollution (Phytoremediation)Pollution caused by the exhaust of cars &homes and departments’ heating devices and appliances will incurirreparable damages to the health of human beings, animals, water, soil and air.Increase of diseases in human beings, eradication of many plants and endangerment of many generations of animalsare a solid evidence of the said claim.For this purpose, biological scientists and environmentalists forced to think of natural ways (biologic) for fightingwith pollutions. The use of plants is the simplest biological way, because, using plants is a non-technical and cost-effective method in terms of technology [1, 7].Soil Pollution Control Technique Caused by Lead Existing in ItFungi are used to fight lead existing in soil, because, satisfactory and good reports have been received both incoexistence among plants and fungi like ARBASCULAR – MYCORRIZA FUNGI (AMF) in absorption of the lead.Creating colony of this fungus on the root of plants will cause increase of root level for absorption of the lead whichresults in more absorption of the lead element to the host plant. These reports indicate that these fungi help plantssurvive and tolerate pollution better. The researchers consider this tolerance as a result of protection of their roots bythe fungi in soil [2].The protective effect of fungi for the plants is as follows: MYCORIZA colony is increased on root and all surfacesof the plant with the aim of absorbing heavy metals like lead. Even if the plant is able to accumulate a lot of theseelements, the fungus plays an intermediary role for absorption of heavy metals again.In lead mines, a type of fungus named Spurs Plows Niger can also be sued. As compared with the other fungi, thisfungus can absorb more lead from the environment without experiencing any damage in this respect. So, these typesof fungi can help improve soil infected to the heavy metals like lead [13, 14].Phytoremediation Technique to Control Soil PollutionPhytoremediation is a cost-effective, environmental and scientific technique which is suitable for developingcountries and is considered as a valuable business. Unfortunately, despite this potential, the technique, as atechnology, has not yet commercially used in some countries like our country. Through the use of Green PlantsEngineering like herbaceous and woody species, phytoremediation is used for removing pollutants from water andsoil or decreasing risks of environmental pollutants like heavy metals, rare elements, organic compounds andradioactive materials [6, 9].Heavy metals are the most important mineral pollutants and soil microorganisms are able to decompose organicpollutants. But for microbial decomposition of metals, there is a need for organic or metal changes, in which, plantsare presently used for this part.Although way of using the plants, which are polluted in this form, is the major concern of the experts, strategy ofgenerating energy opened another chapter for the scientists as one of the most essential aspects of today’s life [2].From a global perspective, soil crust is considered as the third major component of the human environment afterwater and air. In addition to the base of terrestrial living organism especially human communities, soil is consideredas a unique environment for living of different life especially plants. Unlike the weather, soil pollution cannot be
  7. 7. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3107Scholars Research Librarymeasured easily in chemical compound terms. In other words, a clean or pure soil is indefinable. Then, we have tostudy potential issues of the soil pollution within the framework of anticipated probable damages and hazards inperformance of soil. With the development of manmade projects and contamination of soils by the heavy metals, thestructure of soil will be dangerous and poisonous for the growth and development of plants and will entanglebiodiversity of the soil as well [14].In phytoremediation method, plants are classified based on absorption mechanism and soli pollution to the heavymetals is reduced through chemical, physical and biological methods. Based on the researches made by the Bureauto Study Water and Soil Pollution of the Department of the Environment (DoE), removal of soil pollution is usuallycarried out by two methods: 1- inside the site and 2- outside the site. In outside-of-the-site method, the contaminatedsoil is transferred to the other place and after removal of its pollution, it is returned to the first place. In anothermethod i.e. inside-the-site, there is no need to transfer or move the soil, rather, when pollutants are turned intoorganic, capability of their biological uptake is reduced. To reduce pollution of mineral pollutants in soil, thefollowing methods of organic, complex and soil increase by the lime can be used [12].But most of these methods are expensive and will destruct the environment. In technology of using plants asphytoremediation, green plants and their relationship with soil microorganisms is used to reduce soil andgroundwater pollution. This technology can be used for removing each of two pollutants of soil i.e. organic andinorganic.The studies show that application of physicochemical techniques will cause eradication of soil usefulmicroorganisms like microriza nitrogen stabilizers and consequently, it will weaken biological activities of the soilwhich will cost dearly in comparison with the phytoremediation technique [3].Soil and water plants are used in rizo-filtration method that pollutants of contaminated water resources are depositedor condensed with little density in their roots. This method is applied especially for industrial wastewater treatmentplants, agricultural runoff and/or wastewater of acid mines and is suitable for the metals like lead, cadmium, copper,nickel, zinc and chrome. The plants like Indian mustard, sunflower, tobacco, rye and corn enjoy this capability.These plants enjoy high capability of absorbing lead from the sewage system, based on which, sunflower has thehighest capability of absorbing lead from the sewage than other plants [10].In another method, restricting mobility and availability of pollutants is carried out in soil through using power of theroot. This method is usually used in soil, sediment and sludge to reduce the pollution and is carried out throughabsorption, deposition, complex and/or reduction of the capacity [1].In plant evaporation method, plants absorb pollutants from the soil and then convert them into the steam and transferwith the transpiration and atmosphere operation. This method is used in growing trees to absorb organic andinorganic pollutants. In another method which is known as "Reduced Plan", the plant helps removal of pollutionfrom soil and underground waters with its metabolism through transferring, decomposition, stabilization andsublimation of the pollutant compounds. In this method, organic compounds are broken into simpler molecules andcan be entered inside the plant tissue. The studies have shown that plants enjoy the enzymes that can decomposewaste of chlorinated solvents like tri-chlorine, ethylene and other insecticides [4].Heavy Metals and Their Availability in SoilHeavy metals are the elements with atomic weight, ranging from 63.54 to 200.59, and specific weight more than 4.Some heavy metals are required little amount of living organisms although excessive increase of the same essentialheavy metals can be harmful for the organisms. The unnecessary heavy metals include arsenic, antimony, cadmium,chrome, mercury and lead. These metals are very important with relation to the pollution of soil and surface watersand are taken into consideration in phytoremediation science [8].Reaction of Plants to Heavy MetalsPlants have three basic strategies for the growth in soils contaminated to the heavy metals. 1- The species whichprevent entrance of metals to their aerial parts or hold concentration of metals low in the soil. 2- The species whichaccumulate metals in their aerial organs and return them to the soil. 3- The plants which can condensate metals intheir aerial organs and also the plants which absorb high condensation of pollutants and condense in their root, stemor leaf [5, 11].Application of Genetic Engineering to Improve PhytoremediationIn this technique, tolerance of species can be increased to the environmental pollutant metals through the geneticdiversity existing inside each species and stimulation of genetic characteristics of the species. The studies have
  8. 8. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3108Scholars Research Libraryshown that production of plants with high potential of phytoremediation and biomass production is effective toimprove phytoremediation method. The inoculation of the effective genes in accumulation of the metals to the plantswhich are taller than the natural plants will cause increase of final biomass production [8].Phytoremediation methods have some limitations, for example, in a type of this method, phytoremediation method iseffective at the range of three-feet from soil surface and maximum 60-feet from the underground waters. Thismethod is applied vastly for the places which pollution density in them is between low to average level and isseverely dependent on the soil acidity [2].The results of research activities made by scientists indicate that soil acidity increases availability of metals to agreat extent. Of course, acidic soil may have negative effects. For example, increased solubility of some toxic metalsand washing them to the underground waters will cause outbreak of environmental hazards which should becontrolled under specific conditions [9].Consuming Phytoremediation ProductsThe way of consuming contaminated plants is one of the barriers to commercial implementation ofphytoremediation. After harvesting, soil pollution is reduced by the plant but a great amount of dangerous biomass isproduced. The studies show that compost production and condensation are the two methods which were proposed bymany researchers for the biomass management of the contaminated plants. Thermo-chemical change is the bestmethod for consuming biomasses produced by phytoremediation. As an energy source, biomass has commercialusage in this method. This biomass includes carbon, hydrogen and oxygen which are known as oxygenatedhydrocarbons. Hemicelluloses, cellulose, minerals and ash is the main component of each lignin biomass whichenjoy a high amount of humidity, volatile materials and bulk density but have low thermal value. The percent ofthese components varies from species to species, in which, management of this volume of waste is a difficult taskand needs volume reduction [12].Energy ProductionIncinerating and producing gas is the important methods for generating thermal and electrical energy which can beextracted from the infected plants. Recycling this energy from biomass, by incinerating or producing gas, can haveeconomic value, because, it cannot be consumed as fodder or fertilizer. Incinerating is a simple method whichshould be put under strict controlled situations. In this method, biomass is decreased between 2 to 5 percent and ashcan be consumed appropriately. The studies have shown that incinerating dangerous wastes, containing metals, isnot correct and logical in an open-air space, because, the gases released to the environment may be harmful. Undersuch circumstances, volume is only reduced and the produced heat is wasted.The studies made by the Bureau to Study Water and Soil Pollution of the Department of the Environment (DoE)show that gas production is one of the cases for controlling biomass which is produced through a series of chemicalchanges of the clean combustion gases with high thermal efficiency. So, this gas combination is called "Pyro Gas"which can be incinerated for producing thermal and electrical energy.Gas production is carried out in a gas exchanger within complicated stages of drying, heating, thermaldecomposition and chemical reactions of combustion which is occurred simultaneously. The researchers havereported that pyrolysis is a new method for the management of urban wastes and it is possible to use it for biomassmanagement of the contaminated plants. Pyrolysis decomposes materials under anaerobic situations and has no airemissions [3, 7].Thus, heavy metals remain in the coke which can be used in the melting furnace. Although high cost ofestablishment and operating procedures is a restricting factor, if used only for the plant, it can be suitable for thepollutant plants and urban wastes. The researchers have conducted research activities on plant species with highbiomass and have shown that this method can have both positive results and effective environmental benefits.Removal of Soil Oil Pollutions through Using Phytoremediation TechniqueOil pollution is an inevitable consequence of rapid population growth and industrialization process. In the samedirection, soil pollution by the oil hydrocarbon materials can be observed vastly around exploration and refininginstallations typically via transfer routes of these materials across southern oilfield provinces of the countryIn addition to the direct emission of these pollutants, the dusts from burning gases with oil have added toxic andharmful materials to the soils of the region for many years. Moreover having vast impact on ecosystem of the region,these pollutants are penetrated into the food chain and also human communities gradually and consequently,threaten health of human beings.
  9. 9. Saeid Mahdeloei et al Annals of Biological Research, 2012, 3 (7):3101-3109_____________________________________________________________________________3109Scholars Research LibraryPresently, dire need is felt to prevent spread of these pollutions to the region and also cleaning up the contaminatedregions.For this purpose, different methods can be used. Phytoremediatin is one of these methods which take advantage ofplants and microorganisms along with them for cleaning up the contaminated environments. (Water and soil)In fact, phytoemediation will provide suitable conditions for the growth and deployment of the plant as well asincrease of natural cleanup activities through the application of human interventions such as agricultural technology(plowing and fertilizing). Cost-effectiveness, inexpensiveness and its simplicity is the most important advantage ofthis method than any other methods. In this method, selection of suitable plant is of paramount importance whichdepends on the climatic condition of the region, type and degree of soil pollution [1,14].Future of Phytoremediation Technique in Controlling Soil PollutionAlthough this science is developing very rapidly, the studies show that commercial phytoremediation should be ableto compete with the other technologies in terms of time. More phytoremediation tests have been carried out inhydroponics environment in laboratory scale and heavy metals have been given to them, while soil environment iscompletely different. In real soil, there are many metals in insoluble forms and their availability is low. The saidissue is the greatest problem. Many plants have not yet been known that should be identified and more should beknown about their physiology [6].Although 10 years have passed from the initial application of the phytoremediation technology in the world, thisscience has been developed very rapidly and today, phytoremediation has vast application on organic, inorganic andradioactive materials. This process is sustainable, affordable and is suitable for the developing countries. Generally,this method is cost effective as well. The studies show that efficiency of this method is increased with theapplication of fast-grown plants with high biomass and high absorption power of the heavy metals. In mostcontaminated places, appropriate species have been identified for the removal of pollution. Two methods ofcomposting and condensing can be regarded as preliminary stages for reducing production volume of these plantsbut it should be considered that leachate of condensation should be collected completely. The researchers believethat incinerating consumes the least possible time among the methods which reduce the pollutants biomass and ismore suitable in comparison with the direct incineration in environmental terms [10].However, it is observed that today world can devise improvements with inspiration of the nature and its virgin non-diminishable system for what the human being has destroyed with his hand which undoubtedly is not easier thanpreventing pollution of resources especially soil resources.REFERENCES[1] Bavandi, Bijan, Ecosystem, Publications of the Department of the Environment (DoE), 1975.[2] Bahram Soltani, Kambiz, An Introduction on Identification of Environment, Publications of the Department ofthe Environment (DoE), 1986.[3] Erfan-Manesh, Majid & Afyouni, Majid, Environment, Water, Soil and Air Pollution, Publications of ArkanDanesh, 2008.[4] Commoner, Bari, Human and Environment (Translated by Behrouz Dehzad), Moj-e Sabz Publications, 2003.[5] Kordovani, Parviz, Natural Ecosystems, Ghoms Publications, 1996.[6] Miller, J. T., Living in Environment (Traslated by Majid Makhdoum), Tehran University Printing andPublications Institute, 2003.[7] Beeton, A.M., Changes in the Environment and Biota of the Great Lakes, In Eutrophication: Causes,Consequences, Corrective, Symposium, National Academy of Science, Washington, D.C., 1969.[8] Jordan, Gil., The Soviet Environment, Clear Creek, 1971.[9] Goldman, Marshall I., Environmental Disruption in the Soviet Union, New York, McGraw-Hill, 1971.[10] Hazardous Waste “Soil Treatment” Reference Library Peroxide Application, 1998.[11] Pfife, Daniel. Killing the Goose, Environment, 13, 3, 1971.[12] http://www.Bioweb.Pasteur[13] http://www.Coneord.org[14] http://www.ebi.ac