Canada, acid rain

For Further Reading J. P. Grime, Biodiversity and ecosystem function The debate deepens, Science, vol. 277, 1997, pp. 1260-1261. C. K. Fajcwski and H. T. Mullins, Historic calcite record from the Finger Fakes, New York Impact of acid rain on a buffered terrane, Geological Society of America Bulletin, vol. 115, 2003, pp. 373-384. J. Raloff, Pollution helps weeds take over prairies, Science News, vol. 150, 1996, p. 356. Environment Canada, Acid rain, http //www.ec.gc.ca/acidrain/. 

Environment Canada. Acid Rain and. . . Forests. May 19, 2005. Available at www.ec.gc.ca/acidrain/acidforest.html. 

Sulfuric acid is very corrosive to both living things and building materials. Another result of this type of pollution is acid rain. In many parts of the northeastern United States and southeastern Canada, acid rain has caused some freshwater lakes to become too acidic to support any life (Fig. 5.32). 

Provincial Agreements for the Eastern Canada Acid Rain Program, 1990 to 1994... 

Selection of pollution control methods is generally based on the need to control ambient air quaUty in order to achieve compliance with standards for critetia pollutants, or, in the case of nonregulated contaminants, to protect human health and vegetation. There are three elements to a pollution problem a source, a receptor affected by the pollutants, and the transport of pollutants from source to receptor. Modification or elimination of any one of these elements can change the nature of a pollution problem. For instance, tall stacks which disperse effluent modify the transport of pollutants and can thus reduce nearby SO2 deposition from sulfur-containing fossil fuel combustion. Although better dispersion aloft can solve a local problem, if done from numerous sources it can unfortunately cause a regional one, such as the acid rain now evident in the northeastern United States and Canada (see Atmospheric models). References 3—15 discuss atmospheric dilution as a control measure. The better approach, however, is to control emissions at the source. 

In a relatively small continental area such as Europe, there is not much difference between what would be considered the regional scale and the continental scale. However, on most other continents there would be a difference between what is considered regional and what continental. Perhaps of greatest concern on the continental scale is that the air pollution policies of a nation are likely to create impacts on neighboring nations. Acid rain in Scandanavia has been considered to have had impacts from Great Britain and Western Europe. Japan has considered that part of their air pollution problem, especially in the western part of the country, has origins in China and Korea. Cooperation in the examination of the North American acid rain problem has existed for a long time between Canada and the United States. 

Acid rain is the popular term for a very complex environmental problem. Over the past 25 years, evidence has accumulated on changes in aquatic life and soil pH in Scandinavia, Canada, and the northeastern United States. Many believe that these changes are caused by acidic deposition traceable to pollutant acid precursors that result from the burning of fossil fuels. Acid rain is only one component of acidic deposition, a more appropriate description of this phenomenon. Acidic deposition is the combined total of wet and dry deposition, with wet acidic deposition being commonly referred to as acid rain. 

Atmospheric emissions of sulphur dioxide are either measured or estimated at their source and are thus calculated on a provincial or state basis for both Canada and the United States (Figure 2). While much research and debate continues, computer-based simulation models can use this emission information to provide reasonable estimates of how sulphur dioxide and sulphate (the final oxidized form of sulphur dioxide) are transported, transformed, and deposited via atmospheric air masses to selected regions. Such "source-receptor" models are of varying complexity but all are evaluated on their ability to reproduce the measured pattern of sulphate deposition over a network of acid rain monitoring stations across United States and Canada. In a joint effort of the U.S. Environmental Protection Agency and the Canadian Atmospheric Environment Service, eleven linear-chemistry atmospheric models of sulphur deposition were evaluated using data from 1980. It was found that on an annual basis, all but three models were able to simulate the observed deposition patterns within the uncertainty limits of the observations (22). 

Acid Rain A National Sensitivity Assessment, Inland Waters Directorate, Environment Canada, Ottawa, Ontario, Fact Sheet and maps, 1988. Berden, M. Nilsson, S.I. Rosen, K. Tyler, G. Soil Acidification Extent, Causes, and Consequences, National Swedish Environmental Protection Board, Rept. 3292, 1987, pp 164. 

Acid rain monitoring data in North America have been gathered by Environment Canada and stored in the National Atmospheric Chemistry (NatChem) Database, details of which can be found at www.airquality.tor.ec.gc.ca/natchem. Analysis of the deposition chemistry data has confirmed that wet sulfate deposition did indeed decline in concert with the decline in SO2 emissions in both eastern Canada and the... 

Not all lakes that are exposed to acid rain become acidified. In areas where there is plenty of limestone rock, lakes are better able to neutralize acid. In areas where rock is mostly granite, the lakes cannot neutralize acid. Unfortunately, much of eastern Canada—where most of the acid rain falls—has a lot of granite rock and therefore a very low capacity for neutralizing acids. 

The Eastern Canadian Acid Rain Program was highly successful at reducing SO2 emissions and sulfate wet deposition in eastern Canada (see Figure 10). Sulfur emissions actually declined more than the desired 50% by 1994, and have continued to decline modestly in the present. These SO2 emissions in the United States have also reduced dramatically, particularly since the implementation of the Canada-United States Air Quality Accord in 1991. This has been especially important to the aquatic and terrestrial ecosystems in eastern Canada, since US emissions are responsible for a large proportion of the acid deposition received in eastern Canada due to transboundary transport. 

The critical load exceedance pattern is shown across eastern Canada for the years 1980 and 1995. The differences in the exceedance patterns of 1980 and 1995 indicate that the area of exceedance, and the amount of exceedance in most areas, declined considerably in 15 years. By way of comparison, the 1995 area of exceedance is 61% lower than that in 1980, a clear illustration that the decline in annual sulfate deposition from 1980 to 1995 resulted in a large reduction to the number of lakes vulnerable to acid rain. In spite of the decline, there still exist in 1995 large areas in eastern Canada where the critical loads are exceeded. In 1995, this area was approximately 510,000 km2 and encompassed roughly 60,000 lakes. 

Environment Canada (1997). Canadian Acid Rain Assessment, Volume 3 The Effects on Canada s Lakes, Rivers and Wetlands. 

Acid rain. Lakes in some areas of the world are now registering very low pH s because of excess acidity in rain. This was first noticed in Scandinavia and is now prevalent in eastern Canada and the northeastern U.S. Normal rainfall is 5.6 (because of CO2 in the air forming H2CO3). However, excessive use of fossil fuels (especially coal) with high sulfur and nitrogen content cause sulfuric and nitric acids in the atmosphere from the sulfur dioxide and nitrogen oxide products of combustion. Some rain in the Adirondack Mountains of upper New York State has been measured with a pH of 3.0. This problem is not specific to the chemical industry but should be of concern to all of us. 

Sulfuric acid is a stronger acid than sulfurous [pAa(l) < 0, p7fa(2) = 1.99 at 25 °C and infinite dilution] rain as acidic as pH 2.1 has been recorded at Hubbard Brook, New Hampshire, and the pH of water droplets in clouds can be as low as 1.5 (for comparison, the pH of rainwater saturated with atmospheric CO2 is about 5.6 at 15 °C). Acid rain destroys building materials (especially marble), kills fish and vegetation, accelerates metallic corrosion (Sections 16.5 and 16.7), and can be directly harmful to humans (e.g., it causes the alligator skin condition reported in Cubatao, Brazil). Sulfate rain is not completely without redeeming features, as many soils (e.g., in southern Alberta, Canada) are sulfur-deficient. On balance, however, its acidity is unacceptable, and sulfur oxide emissions must be controlled at the source. Several control measures are possible ... 

The topic of acid rain during the 1980s and early 1990s was one of controversy and of incomplete answers in terms of official policy and science—after an expenditure of many millions of dollars. In 1980. the National Acid Precipitation Assessment Program (NAPAP) was established and subsequently consumed thousands of scientific research hours and costly field investigations, including the use of numerous helicopter expeditions to northwestern mountain and lake areas of the United States and Canada. Thousands of hours of computer power were consumed. 

Among the many dramatic effects of acid rain are the extinction of fish from acidic lakes throughout parts of the northeastern United States, Canada, and Scandinavia, the damage to forests throughout much of central and eastern Europe, and the deterioration everywhere of marble buildings and statuary. Marble is a form of calcium carbonate, CaC03, and, like all metal carbonates, reacts with acid to produce C02. The result is a slow eating away of the stone. 

Many processes in nature require such a fine pH balance that they are dramatically upset by the shift that has occurred in the pH of rain. Thousands of lakes in the Adirondack region of upper New York State and in southeastern Canada have become so acidic that all fish life has disappeared. Massive tree die-offs have occurred throughout central and eastern Europe as acid rain has lowered the pH of the soil and leached nutrients from leaves. Countless marble statues have been slowly dissolved away as their calcium carbonate has been attacked by acid rain. 

Kettles, I.M. and Shilts, W.W. (1994) Composition of glacial sediments in Canadian shield terrane, southeastern Ontario and southwestern Quebec applications to acid rain research and mineral exploration. Geological Survey of Canada Bulletin, 463, Report, 58 pp. 

The combustion of fossil fuels releases sulfur and nitrogen oxides. These oxides react with water vapour in the atmosphere to produce acid rain. Some lakes in northern Canada are dead because acid rain has killed the plants, algae, and fish that used to live in them. Forests in Quebec and other parts of Canada have also suffered from acid rain. 

Acid rain was at one time an important point of contention between the United States and Canada. Much of this acid was the result of the emission of sulfur oxides by coal-fired electricity generating plants in southern Indiana and Ohio. These sulfur oxides, when dissolved in rainwater, formed sulfuric acid and hence acid rain. How many metric tonnes of Indiana coal, which averages 3.5% sulfur by weight, would yield the H2S04 required to produce a 0.9 in. rainfall of pH 3.90 precipitation over a 104 mile2 area ... 

The influence of acids on living things has assumed special importance in the United States, Canada, and Europe in recent years as a result of the phenomenon of acid rain. This problem is complex, and s diplomatic and economic overtones make it all the more difficult to so ... 

The fallout of acid rains of surface waters has been studied for the last 15 years because of the impact on life in the lakes and rivers of Scandinavia, Scotland, and Canada as well as in the northeastern regions of the United States (Kramer and Tessier, 1982 Hilleman, 1983b). 

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