Have been constructed to collect rain samples over

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have been constructed to collect rain samples over large geographical areas. The acidity of rainwater over the course of the entireyear must be measured because pH varies between rainfalls, both seasonally and according to whether the air masses that producethe rain have passed over significant sources of pollution. The pH of rainwater and other forms of precipitation is also measuredover a period of years. In addition to the concentration of hydrogen ions, the concentration of other ions, such as sulfate fromsulfuric acid and nitrate from nitric acid, is measured in the rainwater samples. Such measurements give evidence of the source ofthe acidity—that is, which proportion is attributable to sulfuric acid and which to nitric acid. The pH levels of samples collectedover a large geographical area are plotted on a map, and contours are drawn through equal values of the pH. Such maps showwhich areas are receiving the most acid rain. The amount of sulfate and nitrate being deposited by rain is also plotted separately.Meteorologists also use information about a storm system’s path as it moves across the country. Such atmospheric systems
transport pollutive gases from one area to another. Combining deposition patterns on maps with information about the pathfollowed by a storm shows where the gas residues in rainwater may be coming from and suggests sources of the acidity.Computers have been used to predict where acid rain will fall and how acidic it will be, given the sources and amounts of sulfurand nitrogen emissions, particularly from power plants and smelters, and the weather patterns. Predictions of this type require adetailed knowledge of the atmospheric chemistry by which sulfur dioxide is converted to sulfuric acid and the oxides of nitrogenare converted to nitric acid. This type of modeling is necessary to predict how much reduction in the acidity of rain in a distantarea will result from a given reduction in a power plant sulfur source, for example.The effects of acidity on soils have been the subject of study for many years. Laboratory experiments can demonstrate how soilclays and other minerals react to acid rain, including which chemical species are taken up and which are released. In addition, soilsolutions and minerals are collected and analyzed from actual field areas affected by acid rain. Ideally, such an analysis should becarried out over a period of time to determine whether any changes in the soil solution chemistry are occurring. From aknowledge of thesoil chemistry, it is possible to predict how long a soil can receive acid rain before it loses particular nutrientsor the ability to neutralize the excess acidity.Measuring the acidity and chemical composition of lakes in various areas over long periods and sampling their fish populationsand other biota enables scientists to see increases in lake acidity and to correlate the increases with changes in the populations ofaffected species. In some areas, lakes have been artificially acidified so that the changes in their chemistry and biological

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Term
Fall
Professor
Cluster Byars
Tags
English, pH, Sulfuric acid, Acid rain, Sulfur dioxide

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