Acid Rain (2465 words) Essay Example For Students

Acid Rain (2465 words) Essay Acid RainAcid rain is a serious problem with disastrous effects. Each day this seriousproblem increases, many people believe that this issue is too small to deal withright now this issue should be met head on and solved before it is too late. Inthe following paragraphs I will be discussing the impact has on the wildlife andhow our atmosphere is being destroyed by acid rain. STATISTICS Although there isvery little data, the evidence indicates that in the last twenty to thirty yearsthe acidity of rain has increased in many parts of the United States. Presently,the United States annually discharges more than 26 million tons of sufferdioxide into the atmosphere. Just three states, Ohio, Indiana, and Illinois areresponsible for nearly a quarter of this total. Overall, two-thirds of thesuffer dioxide into the atmosphere over the United States comes from coal-firedand oil fired plants. Industrial boilers, smelters, and refineries contribute26%; commercial institutions and residences 5%; and transportation 3%. Theoutlook for future emissions of suffer dioxide is not a bright one. Between nowand the year 2000, United States utilities are expected to double the amount ofcoal they burn. The United States currently pumps some 23 million tons ofnitrogen oxides into the atmosphere in the course of the year. Transportationsources account for 40%; power plants, 30%; industrial sources, 25%; andcommercial institutions and residues, 5%. What makes these figures particularlydistributing is that nitrogen oxide emissions have tripled in the last thirtyyears. CAUSES Acid rain is a cancer eating into the face of Eastern Canada andthe North Eastern United States. One of the main causes of acid rain is sulphurdioxide. Natural sources which emit this gas are volcanoes, sea spray , rottingvegetation and plankton. However, the burning of fossil fuels, such as coal andoil, are largely to be blamed for approximately half of the emissions of thisgas in the world. When sulphur dioxide reaches the atmosphere, it oxidizes tofirst form a sulfate ion. It then becomes sulphuric acid as it joins withhydrogen atoms in the air and falls back down to earth. Oxidation occurs themost in clouds and especially in heavily polluted air where other compounds suchas ammonia and ozone help to catalyze the reaction, converting more sulphurdioxide to sulphuric acid. However, not all of the sulphur dioxide is convertedto sulphuric acid. In fact, a substantial amount can float up into theatmosphere, move over to another area and return to earth unconverted. Thefollowing are the stoichiometric equations for the formation of sulphuric acid:S (in coal) + O2?_ SO2 2 SO2 + O2?_ 2 SO3 SO3?_ + H2O H2SO4 Nitric oxideand nitric dioxide are also components of acid rain. Its sources are mainly frompower stations and exhaust fumes. Like sulfur dioxide, these nitrogen oxidesrise into the atmosphere and are oxidized in clouds to form nitric acid. Thesereactions are also catalyzed in heavily polluted cloud s where iron, manganese,ammonia and hydrogen peroxide are present. In Canada, the main sulfuric acidsources are non-ferrous smelters and power generation. On both sides of theborder, cars and trucks are the main sources for nitric acid(about 40% of thetotal), while power generating plants and industrial commercial and residentialfuel combustion together contribute most of the rest. In the air, the sulfurdioxide and nitrogen oxides can be transformed into sulfuric acid and nitricacid, and air current can send them thousands of kilometers from the source. When the acids fall to the earth in any form it will have large impact on thegrowth or the preservation of certain wildlife. NO DEFENSE One of the directeffects of acid rain is on lakes and its aquatic ecosystems. There are severalroutes through which acidic chemicals can enter the lakes. Some chemicalsubstances exist as dry particles in the air while others enter the lakes as wetparticles such as rain, snow, sleet, hail, dew or fog. In addition, lakes canalmost be thought of as the sinks of the earth, where rain thatfalls on land is drained through the sewage systems eventually make their wayinto the lakes. Acid rain that falls onto the earth washes off the nutrients outof the soil and carries toxic metals that have been released from the soil intothe lakes. Another harmful way in which acids can enter the lakes is spring acidshock. When snow melts in spring rapidly due to a sudden temperature change, theacids and chemicals in the snow are released into the soils. The melted snowthe n runs off to streams and rivers, and gradually make their way into thelakes. The introduction of these acids and chemicals into the lakes causes asudden drastic change in the pH of the lakes hence the term spring acidshock. The aquatic ecosystem has no time to adjust to the sudden change. Areas in Ontario mainly southern regions that are near the Great Lakes, suchsubstances as limestone or other known antacids can neutralize acids enteringthe body of water thereby protecting it. However, large areas of Ontario thatare near the Pre-Cambrian Shield, with quartzite or granite based geology andlittle top soil, there is not enough buffering capacity to neutralize even smallamounts of acid falling on the soil and the lakes. Therefore over time, thebasic environment shifts from an alkaline to a acidic one. This is why manylakes in the Muskoka, Haliburton, Algonquin, Parry Sound and Manitoulindistricts could lose their fisheries if sulphur emissions are not reducedsubstantially. WHAT IS ACID RAIN? Acidity is measured using a pH scale, with thenumber 7 being neutral. Consequently, a substance with a pH value of less than 7is acidic, while one of a value greater than 7 is basic. It is also worthwhileto note that the pH scale is logarithmic; that is, a substance of pH of 6 is 10 times more acidic than another with a pH of 7. Generally, the pH of 5.6 has beenused as the baseline in identifying acid rain, although there has been muchdebate over the acceptance of this value. Interestingly enough, a pH of 5.6 isthe pH value of carbon dioxide in equilibrium with distilled water. Hence, acidran is defined as any rainfall that has an acidity level beyond what is expectedin non-polluted rainfall. In essence, any precipitation that has a pH value ofless than 5.6 is considered to be acid precipitation. The average mean of pHrainfall in Ontarios Muskoka-Haliburton lake country ranges between 3.95 and4.38 about 40 times more acidic than normal rainfall, while storms inPennsilvania have rainfall pH at 2.8 it almost has the same rating for vinegar. Nike And What It Does To Third World Countrys EssayFBC Fluidized Bed Combustion This process allows sulfur dioxide emissions tobe reduced during the combustion process. A limestone or sand bed are crushedand fluidized. It is essential that a balance is established between the heatliberated within the bed from fuel combustion, and the heat removed by the fluegas as it leaves. The limestone is able to react with the SO2 and reduceemissions by over 90%. After Combustion 1. Wet Flue Gas Desulfurization Thisis a highly effective and cost efficient system of flue gas desulfurization. Thewet scrubber is located downstream of the boiler, and consists of eitherlimestone, lime, or sodium hydroxide. Limestone is the most popular choice andreacts with the gas by the following reaction: CaCO3 + SO2 + H2O + O2?_ CaSO3+ CaSO4 + CO2 + H2O The flue gas enters the absorber and is re-emitted afterbeing scrubbed, at which time the waste solids are removed and disposed of. 2. Dry Scrubbing The process of dry scrubbing involves the contact between dryinggas and the atomized liquid (alkaline based). Upon contacting the flue gas, thedrying gas will convert the atomized droplets into a dry product that can beseparated and disposed of. The dry scrubbing process requires less power tocomplete than wet scrubbing. FINAL THOUGHTS Acid rain is very real and a verythreatening problem. Action by one government is not enough. In order for thingsto be done we need to find a way to work together on this for at least areduction in the contaminates contributing to acid rain. Although there areright steps in the right directions but the government should be cracking downon factories not using the best filtering systems when incinerating or if thefactory is giving off any other dangerous fumes.