Acid Rain (1631 words) Essay Example For Students

Acid Rain (1631 words) Essay Acid RainWhat Causes Acid Rain? One of the main causes of acid rain is sulfur dioxide. 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 sulfur dioxide reaches the atmosphere, it oxidizes tofirst form a sulfate ion. It then Becomes sulfuric 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, changing more sulfur dioxideto sulfuric acid. However, not all of the sulphur dioxide is changed to sulfuricacid. In fact, a substantial amount can float up into the atmosphere, move overto another area and return to earth unconverted. In the following pages I willshow the effects of acid rain on: ? Effect on Trees and Soils ? Effect onLakes and Aquatic Systems ? Effect on Materials ? Effect on Atmosphere ?Effec t on Architecture ? Effect on Humans Effect on Trees and Soils One of themost serious impacts of acid precipitation is on forests and soils. Great damageis done when sulfuric acid falls onto the earth as rain. Nutrients present inthe soils are washed away. Aluminium also present in the soil is freed and theroots of trees can absorb this toxic element. Thus, the trees are starved todeath as they are deprived of their vital nutrients such as calcium andmagnesium. Not all of the sulphur dioxide is converted to sulfuric acid. Infact, a substantial amount can float into the atmosphere, move over to anotherarea and return to the soils unconverted. As this gas returns back to earth, itclogs up the stomata in the leaves, thus hindering photosynthesis. Research hasbeen made where red spruce seedlings were sprayed with different combinations ofsulfuric and nitric acid of pH ranging from 2.5 to 4.5. The needles of theseseedlings were observed to develop brown lesions. Eventually, the needles f alloff. It was also found that new needles grew more slowly at higherconcentrations of acid used. Because the rate at which the needles were fallingwas greater than the rate at which they were replenished, photosynthesis wasgreatly affected, The actual way in which these needles were killed is still notyet known. However, studies have shown that calcium and magnesium nutrients arewashed away from their binding sites when sulfuric acid enters the system. Theyare replaced by useless hydrogen atoms and this inhibits photosynthesis. Effecton Lakes and Aquatic Systems One of the direct effects of acid rain is on lakesand its aquatic ecosystems. There are several routes through which acidicchemicals can enter the lakes. Some chemical substances exist as dry particlesin the air while others enter the lakes as wet particles such as rain, snow,sleet, hail, dew or fog. In addition, lakes can almost be thought of as thesinks of the earth, where rain that falls on land is drained throughthe sew age systems eventually make their way into the lakes. Acid rain thatfalls onto the earth washes off the nutrients out of the soil and carries toxicmetals that have been released from the soil into the lakes. Another harmful wayin which acids can enter the lakes is spring acid shock. When snow melts inspring rapidly due to a sudden temperature change, the acids and chemicals inthe snow are released into the soils. The melted snow then runs off to streamsand rivers, and gradually make their way into the lakes. The introduction ofthese acids and chemicals into the lakes causes a sudden drastic change in thepH of the lakes hence the term spring acid shock. The aquaticecosystem has no time to adjust to the sudden change. In addition, springtime isan especially vulnerable time for many aquatic species since this is the timefor reproduction for amphibians, fish and insects. Many of these species laytheir eggs in the water to hatch. The sudden pH change is dangerous because theacids can ca use serious deformities in their young or even annihilate the wholespecies since the young of many of such species spend a significant part oftheir life cycle in the water. Subsequently, sulfuric acid in water can affectthe fish in the lakes in two ways: directly and indirectly. Sulfuric acid(H2SO4) directly interferes with the fishs ability to take in oxygen, salt andnutrients needed to stay alive. For freshwater fish, maintaining osmoregulationis key in their survival. Osmoregulation is the process of maintaining thedelicate balance of salts and minerals in their tissues. Acid molecules in thewater cause mucus to form in their gills and this prevents the fish to absorboxygen as well. If the buildup of mucus increases, the fish would suffocate. Inaddition, a low pH will throw off the balance of salts in the fish tissue. Saltslevels such as the calcium (Ca+2) levels of some fish cannot be maintained dueto pH change. This results in poor reproduction their eggs produced would bedama ged; they are either too brittle or too weak. Decreased Ca+2 levels alsoresult in weak spines and deformities. For example, crayfish need Ca+2 tomaintain a healthy exoskeleton; low Ca+2 levels would mean a weak exoskeleton. The Samurai: Warrior and Ruler of Ancient Japan EssayBibliographyElliott, Thomas C., and Robert G. Schwieger (Editors). The Acid RainSourcebook. New York: McGraw-Hill, Inc., 1984. Bown, William. Europesforests fall to acid rain. New Scientist. Vol. 127. August 11, 1990. p. 17Calvert, Jack G.(Editor) SO2, NO and NO2 Oxidation Mechanisms: AtmosphericConsiderations Acid Rain Precipitation Series, Volume 3. Toronto:Butterworth Publishers, 1984.