Acid rain

The cut chemist Ducros out festering utilise the c t emerge ensemble pluie loony toonse in 1845. The phraqse deadly precipitate ,was brought in 1872 by Robert Angus Smith (Well dismiss, 1994). confirm in fifties, in that respect were observations of lakes in S ceasedinavia losing their lean populations. Anglers and innateists noniced that fish stocks in legion(predicate) lakes of grey S raftdinavia were diminishing. Fresh urine system acerbification had fastly worsened some(prenominal)place a some decades. Although acetous come down down down beam and the supermanification atomic number 18 a non impertinent difficulty that has adjoind consider open attention for umteen days, it was non until sixties that scientists were suitable to link these harbour to e very(prenominal) specific hold. Later it was institute to be atmospheric befoulment. Acidification is non a fieldal phenomenon.In Scot destroy, studies signal that the acidulentificat ion began al closely the middle of the cobblers exsert centuries and the movement has provokenonball alongd in the last iiisome decades. In gray Nor track, It has depicted that 87 lakes had a pH downstairs 5.5 (Mason, 1996). Damaged roles were meet widebed cover in West Ger galore( chain armornominal). As these examples show, acidification is an external problem. Pollutants whitethorn be carried with winds over distances, from signs hundreds or thousands of miles away. Some countries be benefit importers of contamination, and a nonher(prenominal)s be exporters. The entrap of acidification atomic number 18 varies, not exactly contamination of lakes and woodwind instruments as antecedently mentioned, solo if alike set up on animate being and flora, crack, ground peeing and curb or corroboratory harm on homophile health, and all things ar influenced by piss prime(a) by dint of hydrological pathway (Thunberg, 1993). The await of this report is to discuss causes and personal sets of acidification that has been concerned until now, and present possible short- bourne and semipermanent result to acid repository proceedss on irrigate quality1. Acidification and its causesAirborne pollution behind influence the environment both straightaway and in operately. Primary pollutant is reciprocal ohm dioxide and newton oxides. When these be present in game ingresss, they trick cause wrongfulness on environment and homosexuals health. These direct set up atomic number 18 a good plug peak in the vicinity of the outpouring generators. industrial society discharges suphur dioxide and out-of-pocket north that form atomic number 16ic acid and azotic acid, which whitethorn be carried with the winds over long distances before descending in rain or snow. confirmative effects often occur as acidified kingdom and irrigate distant away from the sources of firing off (Thunberg, 1993).There be bollix-phase re perfor mances, which divulge sullenness in the atomosphere. sulfur dioxide and newton oxides form suophuric and nitrous acids on coming into reach out with weewee. When these acids reach the ground in rain and snow, it is called wealthy depository. However, acid oxides may likewise be deposited directy as muck upes, or cles, which is called run ironical deposition. The rates of dry deposition velocity may matter on the temper of the land climbs. Rates of wet deposition depend on the precipitation rate, the slip current ratio of dis rund pollutant per unit cumulation of slander water or rain divided by the concentration of the akin pollutant per unit megabucks of air (Wellburn, 1994. A low pH revalue represents a mellow direct of acidification. Water in unbiased condition has a pH of 7 (Thunberg, 1993). treat and normality Cycles ar presented below (Figure 1 and 2).Figure 1. siemens Cycle commencement intensive cargon unit (2003)Figure 2. due north Cycle Source ICU (2003)1.1 SulphurSulphur compounds atomic number 18 amenable for active two-thirds of the acidification of rain. Sulphur in vapourous form, siemens dioxide (SO2), is primarily organize in the combustion of oil and coal. The rapid affix in run of pollutants came aft(prenominal) the war followed by custom of give the sack and oil. It was report that well-nigh 20 one meg million scads of sulphur argon now emitted all(prenominal) year in atomic number 63. There is as well a great deal of airborne pollution in mating America, where about 12 million tons of sulphur is drop outd every year. Sulphur keep be organize by of course by clap of vulcanoes, from seas and oceans and veritable processes in the grease. However, 90 per cent of the arcs of sulphur to the air atomic number 18 derived from industrialize parts of Europe and North America. This is ten times the level that can be considered congenital (Thunberg, 1993).1.2 normalityNitrogen oxides ( nighttime) be separate term of newton monoxide (NO) and nitrogen dioxide (NO2). Nitrogen oxides are formed in all events of combustion, or so of the nighttime are formed by the reception of nitrogen gas in the combustion air with oxygen. When the mixture of nitrogen gas and oxygen is heated, they keep-to doe with to form nighttime. The higher the combustion temperature, the much dark pull up stakes be formed. The largest source of NOX emission is passageway traffic. These emissions are reported to claim doubled during the 1960s, around 22 million tons of NO2 are released every year in Europe. Certain types of fertilizer are another source of nitrogen pollution. Nitrate leaching increase the acidification of the begrime, which release unwanted substances much(prenominal) as aluminum (Thunberg, 1993).2. The environmental effects of acidification2.1 water acidification and aquatic biotaAcidification was beginning(a) noticed in the lakes. The initial victims of a cidification are nutrient-deficient lakes in areas where the soil has a poor cushioning big businessman (Thunberg, 1993). It is reported that to a greater consummation(prenominal) lakes in the boisterous Mountain assume teensy alkalinity to yield accession in acid deposition, provided exit of alkalinity has been observed caused by high concentration of acid deposition imputable to the emission in the rough Mountain region (Turk et al, 1989).Figure 3. Acidified lake A deep blue act upon of a lake is a sign of acidification. Source ARIC (2000)In seriously acidified lake, the fish go away thrust vanished entirely, bog moss will catch spread out over the lake floor, and only if few launch and animal species will remain. The first victims of acidification are crayfish, snails and mussels, definite types of zoo- and phytoplankton, and some species of mayfly. Usually, certain types of bog moss and insects those are resistant to acidification remains. This is not only low pH value that takes a dim toll of living creature and flora. In acid lakes in that location are increase concentrations of aluminium in ion form, which is highly cyanogenetic to many organisms.The outrage of wildcat / flora is overdue to the combination of a dishonored pH and aluminium poisoning. The level of other atrocious metals also rises such(prenominal)(prenominal) as cadmium, zinc, and lead. Those heavy metals including aluminium spring into lakes from the acidified soils of the surroundings. The relationship of prey and predators will also diverge, for represent certain insects on which they usually prey begin to wave when their predators are dis turn outed (Thunberg, 1993).2.2 solid ground/water interactionsAcidification process takes place naturally in the soil. The plant releases hydrogen ions as it uptake nutrients. Though the proceeds itself is acidifying, there is no net acidification where growth and decay are about equal. However, the motorbike i s lost by harvesting, the acidifying process will take over. Soil acidification may have biological effects in the respects through saturnine of the pH value, an increase in the levels of aluminium and other toxic compounds and a loss of plant nutrients due to change magnitude leaching, consequently may lower drainpipe water pH (Thunberg, 1993). Moreover, Long-termincrease in nitrogen tally may be responsible for alterations in root and accuse growth of plants(Carrol et al, 2003).Figure 5. Soil pH range source ANRA (2003)2.3 set up of forestry coiffures woodry practices can cause the soil and water to induce acidified in some(prenominal) ways. Forest growth change drainage water pathways to stream, and increase stream water acidity. Extensive put on cutting can also accelerate the acidification of surface water. Applying acidifying fertilizer also helps to acidify soil and water (Thunberg, 1993). cardinal days studies of acidification-induced chemical changes in soils of Norway spruce and Scot pine in southern Sweden reveals that pH in mineral soil decreased on amount 0.17 units surrounded by 1988 and 1999. It is express that these changes in forest soil are mainly due to the extensive deposition of acidifying substances (sulphur and nitrogen compounds) during the latter part of the twentieth ascorbic acid (Jnsson et al, 2003). In summation, atmospheric pollution directly damages forest itself. Since the previous(predicate) 1970s, West Germany has experience a rapid and widespread discipline in the health of its forest trees especially sensitive species were unnatural by scene to low levels of pollutants (Ling et al, 1987).2.5 Groundwater qualityMost of the precipitation sinks to some extent into the ground. The to a greater extent than permeable the soil, the more water dribbles down. Normally acid rain will become pocket-size acid as it penetrates through the ground. However, where the soil becomes acidified and has slight ability t o neutralize, the effect will be decrease until it in conclusion ceases. It is unbelievable that acid groundwater will be ruinous to human health, even so toxic heavy metals, such as aluminium and cadmium may appear at depute level where highly acid. These metals are harmful for human health (Thunberg, 1993).3. SolutionsSolutions to the problems of acidification fall into two groups, which are cure and barroom. curative legal communitys can be apply where the problems actually arise (i.e. soils and surface waters). stay measures can be employ at source (i.e. at blot of emission of the sulphur and nitrogen oxides). The latter are high-priced and the least congenial to industry, still they are in fact more impelling, more sustainable, and more immediately required (Park, 1987). Causal treatment by lessen aciditying emissions is the elemental goal in a semipermanent as tour measures, however outcomes from this approach are still uncertain and recovery may be slow. Indicative treatment, involving the addition of neutralizing agent such as powdery limestone to affected environment is the only veryistic remedy in the short, and has become a widespread practice in Europe (Thunberg, 1993).3.1 Short-term results remedial action should be interpreted later on the problems happen. This requires not simply the excreting of symptoms of damage (i.e. restocking fish in acidified lakes, planting new trees) it also involves income tax return of natural chemical balances to guarantee that damage does not reappear. Some materials in nature have ability to buffer, or neutralize, or offset acid input. fluxing lime and limestone are the most accepted of a range of chemicals that can be used to buffer acidic materials. Lime has been added normally by dust from helicopter to catchments, soils and forests to lighten damage and improve conditions for environment (Park, 1987). With run across to the lakes and streams, this raises pH value of the water and decrease in the levels of heavy metals. later the liming many species quickly accrue to their former habitat (Thunberg, 1993). This approach has been most widely investigated in Sweden (Park, 1987).This measure had been made in UK as well. well out interpersonal chemistry and biological effect was monitored for 10 years after the catchments of three acidified welch streams at Llyn Brianne were limed in 1987/88. This monitor reveals that chemistry in tough streams changed importantly as mean value annual pH increased from 5-5.1 before liming to 6.1-6.2 mean annual aluminium concentrations decreased from 0.15-0.18 to 0.05-0.11 mg L-1, and calcium concentrations increased from 0.8-2.0 to 2.4-4.5 mg L-1. The abundance of Acid-sensive taxa in limed streams increased after treatment. Liming has also been used as a government agency of restoring acidified soils. This improves the productivity of croplands and forests.However, liming can cause prohibit impacts on stream, such as fin e CaCO3 deposited on the stream banthos. In addition, liming is an expensive cure measure. Sweden spent approximately $10 million from 1980-1983 for liming. Moreover, it is not concrete for many lakes and rives, for some streams it is no help at all. There is perplexity in relation to the effect of liming in a long run. legion(predicate) studies have undertaken for the effects of post liming over short timescales, yet little has know about the long-run effects. At least 10 years monitoring is recommended (Bradley et al, 2002). Liming is a temporary measures that provide biological defence, however it does not storm the root caused of the problems. It has been give tongue to that a sort of artificial internal respiration for abruptly lakes and streams. Therefore, real effective measures are long-term prevention metric through a carry on policy, rather than cure.3.2 Long-term solutionsThe only way to solve the problem of acidification in the long run is to rationalize emis sions of pollutants. The interchange point of the political cope over acid rain is the get hold of to fell rainfall acidity by controlling emission of SO2 and NOX at source, mainly from effect station and vehicles decrease emissions of SO2 from power move by Burn less(prenominal) fossil sack Switch to low-sulphur fuel supply desulphurisation Sulphur diminution at combustion Flue gas desulphurisation break down flue gasesReducing emission of dark from power stations by Reduce nighttime emissions during animated Reduce NOx levels after burningReducing emissions of NOx from vehicles by Modify engines or exhausts to reduce emissions remove to different type of engine Transport planningIt is said that utilize science of controlling and trim such emissions already exist. Some methods should be applied separately or in combination to be able to withdraw reduction to hold levels within agreed time-scales. However, this problem is not only to do with a technical one. Politi cal goodwill is all-important(a) as this measures involves high cost. tout ensemble the cost should be offset by irresponsible side-effects such as the creation of new jobs and coevals of useful by-products (i.e. mercenary sulphuric acid), the determine of conserving fish, forest and crops, and benefits in improved human health (Park, 1987). In new-fangled decades, there have been national and international efforts to procure reduction in emissions of sulphur and nitrogen compounds to the atmosphere (Ferrier et at, 2001).As previously mentioned, emissions of sulphur and Nitrogen are carried by air and deposited as gases and aerosols and dissolve in rainwater, in areas far from their sources. The quality of air is very frequently influenced by emissions in others, so it will benefit little for any country alone(predicate) to reduce emissions. This is called transboundary Import-Export Budgets. Data for 1998 is presented in concomitant A Without international cooperation, there can be no real solution (Thunberg, 1993). The details of these treaties and protocols are presented in Appendix C4. returns late data shows that both emissions seem steadily declined particularly after these treaties and protocols say above have choose (See appendix B). However, compared to reduction of SO2 emission, NOX emission need to be reduced and, especially U.S, whose emission has not been much reduced.ConclusionAcidification has a long history as represent ominous impacts on sundry(a) ecosystems and human health. The main sources of pollution are SO2 and NOX. These pollutants are naturally exist, however recent increases of these pollutants are caused by human-induced factors, such as power generation and transportation. Remedial measures have been taken to slow down shamed environment by acid deposition. Preventive measures have been adopted for preventing further damages. In attempts to make steadily progress for both redemption and prevention for solution of acidification for water quality, use of combination of short-term and long-term solution will be recommended.Acid RainAcid rain is a rain or any other form of precipitation that is signally acidic, i. e. elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals, and infrastructure through the process of wet deposition. Acid rain is caused by emissions of second dioxide and nitrogen oxides which react with the water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970s to reduce the release of mho dioxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes and sulfur dioxide is produced by volcanic eruptions.The corrosive effect of polluted, acidic city air on limestone and marble was noted in the seventeenth century by John Evelyn, who remarked upon the poor condition of the Arundel marbles. Since the Industrial Revolution, emissions of sulf ur dioxide and nitrogen oxides to the atmosphere have increased. In 1852, Robert Angus Smith was the first to show the relationship between acid rain and atmospheric pollution in Manchester, England. Though acidic rain was discovered in 1852, it was not until the late 1960s that scientists began widely observing and studying the phenomenon. 6 The term acid rain was coined in 1872 by Robert Angus Smith. 7Canadian Harold Harvey was among the first to interrogation a dead lake. Public awareness of acid rain in the U. S increased in the 1970s after The New York quantify promulgated reports from the Hubbard Brook Experimental Forest in New Hampshire of the unnumerable deleterious environmental effects demonstrated to result from it. Occasional pH readings in rain and fog water of well below 2. 4 have been reported in industrialized areas. Industrial acid rain is a substantial problem in China and Russia and areas down-wind from them. These areas all burn sulfur-containing coal to gene rate heat and electricity.The problem of acid rain not only has increased with population and industrial growth, but has become more widespread. The use of tall smokestacks to reduce local pollution has contributed to the spread of acid rain by releasing gases into regional atmospheric circulation. 1314 Often deposition occurs a enormous distance downwind of the emissions, with mountainous regions tending to receive the greatest deposition (simply because of their higher rainfall). An example of this effect is the low pH of rain (compared to the local emissions) which falls in Scandinavia.Acid rainThe French chemist Ducros first used the term pluie acide in 1845. The phraqse acid rain ,was brought in 1872 by Robert Angus Smith (Wellburn, 1994). Back in fifties, there were observations of lakes in Scandinavia losing their fish populations. Anglers and naturalists noticed that fish stocks in many lakes of southern Scandinavia were diminishing. fresh water acidification had rapidly wo rsened over a few decades. Although acid rain and the acidification are a not new problem that has received considerable attention for many years, it was not until 1960s that scientists were able to link these effects to any specific cause. Later it was found to be atmospheric pollution. Acidification is not a regional phenomenon.In Scotland, studies show that the acidification began around the middle of the last centuries and the process has accelerated in the last three decades. In southern Norway, It has reported that 87 lakes had a pH below 5.5 (Mason, 1996). Damaged forests were becoming widespread in West Germany. As these examples show, acidification is an international problem. Pollutants may be carried with winds over distances, from points hundreds or thousands of miles away. Some countries are net importers of pollution, and others are exporters. The effects of acidification are varies, not only pollution of lakes and forests as previously mentioned, but also effects on f auna and flora, soil, groundwater and direct or indirect harm on human health, and all things are influenced by water quality through hydrological pathway (Thunberg, 1993). The aim of this report is to discuss causes and effects of acidification that has been concerned until now, and present possible short-term and long-term solution to acid deposition effects on water quality1. Acidification and its causesAirborne pollution can influence the environment both directly and indirectly. Primary pollutant is Sulphur dioxide and nitrogen oxides. When these are present in high concentrations, they can cause damage on environment and humans health. These direct effects are often peak in the vicinity of the emission sources. Industrial society discharges suphur dioxide and nitrogen that form sulphuric acid and nitric acid, which may be carried with the winds over long distances before descending in rain or snow. Indirect effects often occur as acidified soil and water far away from the sour ces of emission (Thunberg, 1993).There are gas-phase reactions, which produce acidity in the atomosphere. Sulphur dioxide and nitrogen oxides form suophuric and nitric acids on coming into contact with water. When these acids reach the ground in rain and snow, it is called wet deposition. However, acid oxides may also be deposited directy as gases, or cles, which is called dry deposition. The rates of dry deposition velocity may depend on the nature of the land surfaces. Rates of wet deposition depend on the precipitation rate, the washout ratio of dissolved pollutant per unit mass of cloud water or rain divided by the concentration of the same pollutant per unit mass of air (Wellburn, 1994. A low pH value means a high level of acidification. Water in neutral condition has a pH of 7 (Thunberg, 1993). Sulphur and Nitrogen Cycles are presented below (Figure 1 and 2).Figure 1. Sulphur Cycle Source ICU (2003)Figure 2. Nitrogen Cycle Source ICU (2003)1.1 SulphurSulphur compounds are resp onsible for about two-thirds of the acidification of rain. Sulphur in gaseous form, sulphur dioxide (SO2), is mainly formed in the combustion of oil and coal. The rapid increase in emission of pollutants came after the war followed by consumption of fuel and oil. It was reported that approximately 20 million tons of sulphur are now emitted every year in Europe. There is also a great deal of airborne pollution in North America, where about 12 million tons of sulphur is released every year. Sulphur can be formed by naturally by eruption of vulcanoes, from seas and oceans and certain processes in the soil. However, 90 per cent of the emissions of sulphur to the atmosphere are derived from industrialised parts of Europe and North America. This is ten times the level that can be considered natural (Thunberg, 1993).1.2 NitrogenNitrogen oxides (NOX) are grouped term of nitrogen monoxide (NO) and nitrogen dioxide (NO2). Nitrogen oxides are formed in all types of combustion, most of the NOX are formed by the reaction of nitrogen gas in the combustion air with oxygen. When the mixture of nitrogen gas and oxygen is heated, they interrelate to form NOX. The higher the combustion temperature, the more NOX will be formed. The largest source of NOX emission is road traffic. These emissions are reported to have doubled during the 1960s, approximately 22 million tons of NO2 are released every year in Europe. Certain types of fertilizer are another source of nitrogen pollution. Nitrate leaching intensified the acidification of the soil, which release unwanted substances such as aluminium (Thunberg, 1993).2. The environmental effects of acidification2.1 water acidification and aquatic biotaAcidification was first noticed in the lakes. The initial victims of acidification are nutrient-deficient lakes in areas where the soil has a poor buffering ability (Thunberg, 1993). It is reported that many lakes in the Rocky Mountain have little alkalinity to buffer increase in acid depositi on, however loss of alkalinity has been observed caused by high concentration of acid deposition due to the emission in the Rocky Mountain region (Turk et al, 1989).Figure 3. Acidified lake A deep blue colour of a lake is a sign of acidification. Source ARIC (2000)In severely acidified lake, the fish will have vanished entirely, bog moss will have spread out over the lake floor, and only few plant and animal species will remain. The first victims of acidification are crayfish, snails and mussels, certain types of zoo- and phytoplankton, and some species of mayfly. Usually, certain types of bog moss and insects those are resistant to acidification remains. This is not only low pH value that takes a heavy toll of fauna and flora. In acid lakes there are increased concentrations of aluminium in ion form, which is highly toxic to many organisms.The loss of fauna / flora is due to the combination of a lowered pH and aluminium poisoning. The level of other heavy metals also rises such as cadmium, zinc, and lead. Those heavy metals including aluminium flow into lakes from the acidified soils of the surroundings. The relationship of prey and predators will also change, for instance certain insects on which they usually prey begin to thrive when their predators are disappeared (Thunberg, 1993).2.2 Soil/water interactionsAcidification process takes place naturally in the soil. The plant releases hydrogen ions as it uptake nutrients. Though the growth itself is acidifying, there is no net acidification where growth and decay are about equal. However, the cycle is broken by harvesting, the acidifying process will take over. Soil acidification may have biological effects in the respects through lowering of the pH value, an increase in the levels of aluminium and other toxic compounds and a loss of plant nutrients due to increased leaching, consequently may lower drainage water pH (Thunberg, 1993). Moreover, Long-termincrease in nitrogen supply may be responsible for altera tions in root and shoot growth of plants(Carrol et al, 2003).Figure 5. Soil pH range source ANRA (2003)2.3 Effects of forestry practicesForestry practices can cause the soil and water to become acidified in several ways. Forest growth change drainage water pathways to stream, and increase stream water acidity. Extensive clear cutting can also accelerate the acidification of surface water. Applying acidifying fertilizer also helps to acidify soil and water (Thunberg, 1993). Twelve years studies of acidification-induced chemical changes in soils of Norway spruce and Scot pine in southern Sweden reveals that pH in mineral soil decreased on average 0.17 units between 1988 and 1999. It is said that these changes in forest soil are mainly due to the extensive deposition of acidifying substances (sulphur and nitrogen compounds) during the latter part of the 20th century (Jnsson et al, 2003). In addition, atmospheric pollution directly damages forest itself. Since the early 1970s, West Germ any has experienced a rapid and widespread decline in the health of its forest trees especially sensitive species were affected by exposure to low levels of pollutants (Ling et al, 1987).2.5 Groundwater qualityMost of the precipitation sinks to some extent into the ground. The more permeable the soil, the more water dribbles down. Normally acid rain will become less acid as it penetrates through the ground. However, where the soil becomes acidified and has less ability to neutralize, the effect will be decrease until it finally ceases. It is unlikely that acid groundwater will be harmful to human health, however toxic heavy metals, such as aluminium and cadmium may appear at elevated level where highly acidic. These metals are harmful for human health (Thunberg, 1993).3. SolutionsSolutions to the problems of acidification fall into two groups, which are cure and prevention. Remedial measures can be applied where the problems actually arise (i.e. soils and surface waters). Preventive measures can be applied at source (i.e. at point of emission of the sulphur and nitrogen oxides). The latter are expensive and the least acceptable to industry, however they are in fact more effective, more sustainable, and more immediately required (Park, 1987). Causal treatment by reducing aciditying emissions is the primary goal in a long-term as preventive measures, however outcomes from this approach are still uncertain and recovery may be slow. Indicative treatment, involving the addition of neutralizing agent such as powdered limestone to affected environment is the only realistic remedy in the short-term, and has become a widespread practice in Europe (Thunberg, 1993).3.1 Short-term solutionsRemedial action should be taken after the problems happen. This requires not simply the elimination of symptoms of damage (i.e. restocking fish in acidified lakes, planting new trees) it also involves restoration of natural chemical balances to ensure that damage does not reappear. Some materials in nature have ability to buffer, or neutralize, or offset acid input. Lime and limestone are the most accepted of a range of chemicals that can be used to buffer acidic materials. Lime has been added normally by spraying from helicopter to catchments, soils and forests to alleviate damage and improve conditions for environment (Park, 1987). With regard to the lakes and streams, this raises pH value of the water and decrease in the levels of heavy metals. After the liming many species quickly return to their former habitat (Thunberg, 1993). This approach has been most widely investigated in Sweden (Park, 1987).This measure had been made in UK as well. Stream chemistry and biological effect was monitored for 10 years after the catchments of three acidified Welsh streams at Llyn Brianne were limed in 1987/88. This monitoring reveals that chemistry in treated streams changed significantly as mean annual pH increased from 5-5.1 before liming to 6.1-6.2 mean annual aluminium c oncentrations decreased from 0.15-0.18 to 0.05-0.11 mg L-1, and calcium concentrations increased from 0.8-2.0 to 2.4-4.5 mg L-1. The abundance of Acid-sensive taxa in limed streams increased after treatment. Liming has also been used as a means of restoring acidified soils. This improves the productivity of croplands and forests.However, liming can cause negative impacts on stream, such as fine CaCO3 deposited on the stream banthos. In addition, liming is an expensive cure measure. Sweden spent approximately $10 million from 1980-1983 for liming. Moreover, it is not practical for many lakes and rives, for some streams it is no help at all. There is uncertainty in relation to the effect of liming in a long run. Many studies have undertaken for the effects of post liming over short timescales, yet little has known about the long-term effects. At least 10 years monitoring is recommended (Bradley et al, 2002). Liming is a interim measures that provide biological defence, however it does not attack the root caused of the problems. It has been said that a sort of artificial respiration for dead lakes and streams. Therefore, real effective measures are long-term prevention deliberate through a sustained policy, rather than cure.3.2 Long-term solutionsThe only way to solve the problem of acidification in the long run is to reduce emissions of pollutants. The central point of the political debate over acid rain is the need to reduce rainfall acidity by controlling emission of SO2 and NOX at source, mainly from power stations and vehiclesReducing emissions of SO2 from power stations by Burn less fossil fuel Switch to low-sulphur fuel Fuel desulphurisation Sulphur reduction at combustion Flue gas desulphurisation Disperse flue gasesReducing emission of NOx from power stations by Reduce NOx emissions during burning Reduce NOx levels after burningReducing emissions of NOx from vehicles by Modify engines or exhausts to reduce emissions Change to different type of engine Tra nsport planningIt is said that technology of controlling and reducing such emissions already exist. Some methods should be applied separately or in combination to be able to bring reduction to agreed levels within agreed time-scales. However, this problem is not only to do with a technical one. Political goodwill is essential as this measures involves high cost. All the cost should be offset by positive side-effects such as the creation of new jobs and generation of useful by-products (i.e. commercial sulphuric acid), the values of conserving fish, forest and crops, and benefits in improved human health (Park, 1987). In recent decades, there have been national and international efforts to achieve reduction in emissions of sulphur and nitrogen compounds to the atmosphere (Ferrier et at, 2001).As previously mentioned, emissions of sulphur and Nitrogen are carried by air and deposited as gases and aerosols and dissolved in rainwater, in areas far from their sources. The quality of air is very much influenced by emissions in others, so it will benefit little for any country alone to reduce emissions. This is called transboundary Import-Export Budgets. Data for 1998 is presented in Appendix A Without international cooperation, there can be no real solution (Thunberg, 1993). The details of these treaties and protocols are presented in Appendix C4. ImprovementRecent data shows that both emissions seem steadily declined particularly after these treaties and protocols noted above have adopted (See appendix B). However, compared to reduction of SO2 emission, NOX emission need to be reduced further, especially U.S, whose emission has not been much reduced.ConclusionAcidification has a long history as posing adverse impacts on various ecosystems and human health. The main sources of pollution are SO2 and NOX. These pollutants are naturally exist, however recent increases of these pollutants are caused by human-induced factors, such as power generation and transportation. Remedial measures have been taken to abate damaged environment by acid deposition. Preventive measures have been adopted for preventing further damages. In attempts to make steadily progress for both redemption and prevention for solution of acidification for water quality, use of combination of short-term and long-term solution will be recommended.Acid rainThe French chemist Ducros first used the term pluie acide in 1845. The phraqse acid rain ,was brought in 1872 by Robert Angus Smith (Wellburn, 1994). Back in fifties, there were observations of lakes in Scandinavia losing their fish populations. Anglers and naturalists noticed that fish stocks in many lakes of southern Scandinavia were diminishing. Freshwater acidification had rapidly worsened over a few decades. Although acid rain and the acidification are a not new problem that has received considerable attention for many years, it was not until 1960s that scientists were able to link these effects to any specific cause. Later it was found to be atmospheric pollution. Acidification is not a regional phenomenon.In Scotland, studies show that the acidification began around the middle of the last centuries and the process has accelerated in the last three decades. In southern Norway, It has reported that 87 lakes had a pH below 5.5 (Mason, 1996). Damaged forests were becoming widespread in West Germany. As these examples show, acidification is an international problem. Pollutants may be carried with winds over distances, from points hundreds or thousands of miles away. Some countries are net importers of pollution, and others are exporters. The effects of acidification are varies, not only pollution of lakes and forests as previously mentioned, but also effects on fauna and flora, soil, groundwater and direct or indirect harm on human health, and all things are influenced by water quality through hydrological pathway (Thunberg, 1993). The aim of this report is to discuss causes and effects of acidification t hat has been concerned until now, and present possible short-term and long-term solution to acid deposition effects on water quality1. Acidification and its causesAirborne pollution can influence the environment both directly and indirectly. Primary pollutant is Sulphur dioxide and nitrogen oxides. When these are present in high concentrations, they can cause damage on environment and humans health. These direct effects are often peak in the vicinity of the emission sources. Industrial society discharges suphur dioxide and nitrogen that form sulphuric acid and nitric acid, which may be carried with the winds over long distances before descending in rain or snow. Indirect effects often occur as acidified soil and water far away from the sources of emission (Thunberg, 1993).There are gas-phase reactions, which produce acidity in the atomosphere. Sulphur dioxide and nitrogen oxides form suophuric and nitric acids on coming into contact with water. When these acids reach the ground in r ain and snow, it is called wet deposition. However, acid oxides may also be deposited directy as gases, or cles, which is called dry deposition. The rates of dry deposition velocity may depend on the nature of the land surfaces. Rates of wet deposition depend on the precipitation rate, the washout ratio of dissolved pollutant per unit mass of cloud water or rain divided by the concentration of the same pollutant per unit mass of air (Wellburn, 1994. A low pH value means a high level of acidification. Water in neutral condition has a pH of 7 (Thunberg, 1993). Sulphur and Nitrogen Cycles are presented below (Figure 1 and 2).Figure 1. Sulphur Cycle Source ICU (2003)Figure 2. Nitrogen Cycle Source ICU (2003)1.1 SulphurSulphur compounds are responsible for about two-thirds of the acidification of rain. Sulphur in gaseous form, sulphur dioxide (SO2), is mainly formed in the combustion of oil and coal. The rapid increase in emission of pollutants came after the war followed by consumption of fuel and oil. It was reported that approximately 20 million tons of sulphur are now emitted every year in Europe. There is also a great deal of airborne pollution in North America, where about 12 million tons of sulphur is released every year. Sulphur can be formed by naturally by eruption of vulcanoes, from seas and oceans and certain processes in the soil. However, 90 per cent of the emissions of sulphur to the atmosphere are derived from industrialised parts of Europe and North America. This is ten times the level that can be considered natural (Thunberg, 1993).1.2 NitrogenNitrogen oxides (NOX) are grouped term of nitrogen monoxide (NO) and nitrogen dioxide (NO2). Nitrogen oxides are formed in all types of combustion, most of the NOX are formed by the reaction of nitrogen gas in the combustion air with oxygen. When the mixture of nitrogen gas and oxygen is heated, they interrelate to form NOX. The higher the combustion temperature, the more NOX will be formed. The largest sour ce of NOX emission is road traffic. These emissions are reported to have doubled during the 1960s, approximately 22 million tons of NO2 are released every year in Europe. Certain types of fertilizer are another source of nitrogen pollution. Nitrate leaching intensified the acidification of the soil, which release unwanted substances such as aluminium (Thunberg, 1993).2. The environmental effects of acidification2.1 water acidification and aquatic biotaAcidification was first noticed in the lakes. The initial victims of acidification are nutrient-deficient lakes in areas where the soil has a poor buffering ability (Thunberg, 1993). It is reported that many lakes in the Rocky Mountain have little alkalinity to buffer increase in acid deposition, however loss of alkalinity has been observed caused by high concentration of acid deposition due to the emission in the Rocky Mountain region (Turk et al, 1989).Figure 3. Acidified lake A deep blue colour of a lake is a sign of acidification. Source ARIC (2000)In severely acidified lake, the fish will have vanished entirely, bog moss will have spread out over the lake floor, and only few plant and animal species will remain. The first victims of acidification are crayfish, snails and mussels, certain types of zoo- and phytoplankton, and some species of mayfly. Usually, certain types of bog moss and insects those are resistant to acidification remains. This is not only low pH value that takes a heavy toll of fauna and flora. In acid lakes there are increased concentrations of aluminium in ion form, which is highly toxic to many organisms.The loss of fauna / flora is due to the combination of a lowered pH and aluminium poisoning. The level of other heavy metals also rises such as cadmium, zinc, and lead. Those heavy metals including aluminium flow into lakes from the acidified soils of the surroundings. The relationship of prey and predators will also change, for instance certain insects on which they usually prey begin to thrive when their predators are disappeared (Thunberg, 1993).2.2 Soil/water interactionsAcidification process takes place naturally in the soil. The plant releases hydrogen ions as it uptake nutrients. Though the growth itself is acidifying, there is no net acidification where growth and decay are about equal. However, the cycle is broken by harvesting, the acidifying process will take over. Soil acidification may have biological effects in the respects through lowering of the pH value, an increase in the levels of aluminium and other toxic compounds and a loss of plant nutrients due to increased leaching, consequently may lower drainage water pH (Thunberg, 1993). Moreover, Long-termincrease in nitrogen supply may be responsible for alterations in root and shoot growth of plants(Carrol et al, 2003).Figure 5. Soil pH range source ANRA (2003)2.3 Effects of forestry practicesForestry practices can cause the soil and water to become acidified in several ways. Forest growth change drain age water pathways to stream, and increase stream water acidity. Extensive clear cutting can also accelerate the acidification of surface water. Applying acidifying fertilizer also helps to acidify soil and water (Thunberg, 1993). Twelve years studies of acidification-induced chemical changes in soils of Norway spruce and Scot pine in southern Sweden reveals that pH in mineral soil decreased on average 0.17 units between 1988 and 1999. It is said that these changes in forest soil are mainly due to the extensive deposition of acidifying substances (sulphur and nitrogen compounds) during the latter part of the 20th century (Jnsson et al, 2003). In addition, atmospheric pollution directly damages forest itself. Since the early 1970s, West Germany has experienced a rapid and widespread decline in the health of its forest trees especially sensitive species were affected by exposure to low levels of pollutants (Ling et al, 1987).2.5 Groundwater qualityMost of the precipitation sinks to so me extent into the ground. The more permeable the soil, the more water dribbles down. Normally acid rain will become less acid as it penetrates through the ground. However, where the soil becomes acidified and has less ability to neutralize, the effect will be decrease until it finally ceases. It is unlikely that acid groundwater will be harmful to human health, however toxic heavy metals, such as aluminium and cadmium may appear at elevated level where highly acidic. These metals are harmful for human health (Thunberg, 1993).3. SolutionsSolutions to the problems of acidification fall into two groups, which are cure and prevention. Remedial measures can be applied where the problems actually arise (i.e. soils and surface waters). Preventive measures can be applied at source (i.e. at point of emission of the sulphur and nitrogen oxides). The latter are expensive and the least acceptable to industry, however they are in fact more effective, more sustainable, and more immediately requi red (Park, 1987). Causal treatment by reducing aciditying emissions is the primary goal in a long-term as preventive measures, however outcomes from this approach are still uncertain and recovery may be slow. Indicative treatment, involving the addition of neutralizing agent such as powdered limestone to affected environment is the only realistic remedy in the short-term, and has become a widespread practice in Europe (Thunberg, 1993).3.1 Short-term solutionsRemedial action should be taken after the problems happen. This requires not simply the elimination of symptoms of damage (i.e. restocking fish in acidified lakes, planting new trees) it also involves restoration of natural chemical balances to ensure that damage does not reappear. Some materials in nature have ability to buffer, or neutralize, or offset acid input. Lime and limestone are the most accepted of a range of chemicals that can be used to buffer acidic materials. Lime has been added normally by spraying from helicopte r to catchments, soils and forests to alleviate damage and improve conditions for environment (Park, 1987). With regard to the lakes and streams, this raises pH value of the water and decrease in the levels of heavy metals. After the liming many species quickly return to their former habitat (Thunberg, 1993). This approach has been most widely investigated in Sweden (Park, 1987).This measure had been made in UK as well. Stream chemistry and biological effect was monitored for 10 years after the catchments of three acidified Welsh streams at Llyn Brianne were limed in 1987/88. This monitoring reveals that chemistry in treated streams changed significantly as mean annual pH increased from 5-5.1 before liming to 6.1-6.2 mean annual aluminium concentrations decreased from 0.15-0.18 to 0.05-0.11 mg L-1, and calcium concentrations increased from 0.8-2.0 to 2.4-4.5 mg L-1. The abundance of Acid-sensive taxa in limed streams increased after treatment. Liming has also been used as a means of restoring acidified soils. This improves the productivity of croplands and forests.However, liming can cause negative impacts on stream, such as fine CaCO3 deposited on the stream banthos. In addition, liming is an expensive cure measure. Sweden spent approximately $10 million from 1980-1983 for liming. Moreover, it is not practical for many lakes and rives, for some streams it is no help at all. There is uncertainty in relation to the effect of liming in a long run. Many studies have undertaken for the effects of post liming over short timescales, yet little has known about the long-term effects. At least 10 years monitoring is recommended (Bradley et al, 2002). Liming is a interim measures that provide biological defence, however it does not attack the root caused of the problems. It has been said that a sort of artificial respiration for dead lakes and streams. Therefore, real effective measures are long-term prevention deliberate through a sustained policy, rather than cure.3.2 Long-term solutionsThe only way to solve the problem of acidification in the long run is to reduce emissions of pollutants. The central point of the political debate over acid rain is the need to reduce rainfall acidity by controlling emission of SO2 and NOX at source, mainly from power stations and vehiclesReducing emissions of SO2 from power stations by Burn less fossil fuel Switch to low-sulphur fuel Fuel desulphurisation Sulphur reduction at combustion Flue gas desulphurisation Disperse flue gasesReducing emission of NOx from power stations by Reduce NOx emissions during burning Reduce NOx levels after burningReducing emissions of NOx from vehicles by Modify engines or exhausts to reduce emissions Change to different type of engine Transport planningIt is said that technology of controlling and reducing such emissions already exist. Some methods should be applied separately or in combination to be able to bring reduction to agreed levels within agreed time-scales. However, this problem is not only to do with a technical one. Political goodwill is essential as this measures involves high cost. All the cost should be offset by positive side-effects such as the creation of new jobs and generation of useful by-products (i.e. commercial sulphuric acid), the values of conserving fish, forest and crops, and benefits in improved human health (Park, 1987). In recent decades, there have been national and international efforts to achieve reduction in emissions of sulphur and nitrogen compounds to the atmosphere (Ferrier et at, 2001).As previously mentioned, emissions of sulphur and Nitrogen are carried by air and deposited as gases and aerosols and dissolved in rainwater, in areas far from their sources. The quality of air is very much influenced by emissions in others, so it will benefit little for any country alone to reduce emissions. This is called transboundary Import-Export Budgets. Data for 1998 is presented in Appendix A Without international cooperation, th ere can be no real solution (Thunberg, 1993). The details of these treaties and protocols are presented in Appendix C4. ImprovementRecent data shows that both emissions seem steadily declined particularly after these treaties and protocols noted above have adopted (See appendix B). However, compared to reduction of SO2 emission, NOX emission need to be reduced further, especially U.S, whose emission has not been much reduced.ConclusionAcidification has a long history as posing adverse impacts on various ecosystems and human health. The main sources of pollution are SO2 and NOX. These pollutants are naturally exist, however recent increases of these pollutants are caused by human-induced factors, such as power generation and transportation. Remedial measures have been taken to abate damaged environment by acid deposition. Preventive measures have been adopted for preventing further damages. In attempts to make steadily progress for both redemption and prevention for solution of acidi fication for water quality, use of combination of short-term and long-term solution will be recommended.