What is the average ph of acid rain

SO 2 emissions were measured at But the sources of SO 2 emissions from the two countries are different. In the U. Canada cannot win the fight against acid rain on its own.

Only reducing acidic emissions in both Canada and the U. More than half of the acid deposition in eastern Canada originates from emissions in the United States. Areas such as southeastern Ontario Longwoods and Sutton, Quebec receive about three-quarters of their acid deposition from the United States. In , the estimated transboundary flow of sulphur dioxide from the United States to Canada was between 3. By , all seven provinces had achieved or exceeded their targets.

In , the provinces, territories and the federal government signed The Canada-Wide Acid Rain Strategy for Post , committing them to further actions to deal with acid rain. Progress under both the Eastern Canada Acid Rain Program and under the Post Strategy, including data on emissions, is reported in the respective annual reports of these two programs.

National Pollutant Release Inventory. The main source of NO x emissions is the combustion of fuels in motor vehicles, residential and commercial furnaces, industrial and electrical-utility boilers and engines, and other equipment.

Overall, NO x emissions amounted to 2. By comparison, U. NO x emissions for amounted to 21 million tonnes - 8 times more than Canada 's emissions. The influence of transboundary flows of air pollutants from the United States into Canada is significant. In Canada , total NO x emissions have been relatively constant since As of , stationary sources of NO x emissions have been reduced by more than , tonnes below the forecasted level at power plants, major combustion sources and metal smelting operations.

In , as part of the Ozone Annex to the Canada-US Air Quality Agreement, Canada committed to an annual cap on NO 2 emissions from fossil-fuel power plants of 39, tonnes in central and southern Ontario and 5, tonnes in southern Quebec.

It also committed to new stringent emission reduction standards for vehicles and fuels and measures to reduce NO x emissions from industrial boilers. The critical load is a measure of how much pollution an ecosystem can tolerate; in other words, the threshold above which the pollutant load harms the environment.

Different regions have different critical loads. Ecosystems that can tolerate acidic pollution have high critical loads, while sensitive ecosystems have low critical loads. Critical loads vary across Canada. They depend on the ability of each particular ecosystem to neutralize acids.

A pH of 7 is neutral; less than 7 is acidic; and greater than 7 is basic. At a pH below 6, fish and other aquatic species begin to decline.

A target load is the amount of pollution that is deemed achievable and politically acceptable when other factors such as ethics, scientific uncertainties, and social and economic effects are balanced with environmental considerations. Under the Canada-Wide Acid Rain Strategy for Post , signed in , governments in Canada have adopted the primary long-term goal of meeting critical loads for acid deposition across the country.

Recently, maps that combine critical load values for aquatic and forest ecosystems have been developed. The maximum amount of acid deposition that a region can receive without damage to its ecosystems is known as its critical load. It depends essentially on the acid-rain neutralizing capacity of the water, rocks, and soils and, as this map of Canada shows, can vary considerably from one area to another.

Critical loads were calculated using either water chemistry models i. Scientists predicted in that a reduction in SO 2 emissions from Canada and the U. This science was based on the effect of sulphur-derived acids in wet deposition on aquatic ecosystems. New science presented in the Acid Deposition Science Assessment assesses the capacity of aquatic and terrestrial ecosystems to receive acids derived from both sulphur and nitrogen in wet and dry deposition.

Improved estimates of dry deposition the sum of gaseous SO 2 , particle sulphate, nitric acid, particle nitrate and other nitrogen species indicate that past estimates of critical loads for aquatic ecosystems are too high, implying that past predictions of the impact of proposed control strategies have been overly optimistic.

In some regions, the critical loads for forest ecosystems are even more stringent that those for aquatic ecosystems. Canada still needs to evaluate the sustainability of forest ecosystems for various levels of acid deposition given the new critical loads for terrestrial ecosystems. It is likely that new science will continue to support the need for further SO 2 emission reductions of this scale or somewhat greater. Without further controls beyond those identified in the Canada-U.

Air Quality Agreement, areas of southern and central Ontario, southern and central Quebec, New Brunswick and Nova Scotia would continue to receive mean annual sulphate deposition amounts that exceed their critical loads. As a result, about 95, lakes would remain damaged by acid rain. Lakes in these areas have not responded to reductions in sulphate deposition as well as, or as rapidly as, those in less sensitive regions.

In fact, some sensitive lakes continue to acidify. In total, without further controls, almost , km 2 in southeastern Canada-an area the size of France and the United Kingdom combined-would receive harmful levels of acid rain; that is, levels well above critical load limits for aquatic systems. One measure of the acidity of acid rain is the pH.

The pH of rain depends on two things: the presence of acid-forming substances such as sulphates, and the availability of acid-neutralizing substances such as calcium and magnesium salts.

Clean rain has a pH value of about 5. By comparison, vinegar has a pH of 3. Although the acidity of acid rain has declined since , rain is still acidic in eastern Canada. For example, the average pH of rain in Ontario's Muskoka-Haliburton area is about 4. Reductions in the acidity of acid rain are due to reductions in emissions of SO 2. Lakes that have been acidified cannot support the same variety of life as healthy lakes.

As a lake becomes more acidic, crayfish and clam populations are the first to disappear, then various types of fish. Many types of plankton-minute organisms that form the basis of the lake's food chain-are also affected. As fish stocks dwindle, so do populations of loons and other water birds that feed on them. The lakes, however, do not become totally dead. Some life forms actually benefit from the increased acidity. Lake-bottom plants and mosses, for instance, thrive in acid lakes.

So do blackfly larvae. 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.

There are many ways the acidification of lakes, rivers and streams harm fish. Mass fish mortalities occur during the spring snow melt when highly acidic pollutants-that have built up in the snow over the winter-begin to drain into common waterways. Such happenings have been well documented for salmon and trout in Norway.

More often, fish gradually disappear from these waterways as their environment slowly becomes intolerable. Some kinds of fish such as smallmouth bass, walleye, brook trout and salmon, are more sensitive to acidity than others and tend to disappear first.

Even those species that appear to be surviving may be suffering from acid stress in a number of different ways. One of the first signs of acid stress is the failure of females to spawn. Sometimes, even if the female is successful in spawning the hatchlings or fry are unable to survive in the highly acidic waters.

This explains why some acidic lakes only have older fish in them. A good catch of adult fish in such a lake could mislead an angler into thinking that all is well. Many plants, such as evergreen trees, are damaged by acid rain and acid fog. I've seen some of the acid-rain damage to the evergreen forests in the Black Forest of Germany.

Much of the Black Forest was indeed black because so much of the green pine needles had been destroyed, leaving only the black trunks and limbs! You also might notice how acid rain has eaten away the stone in some cities' buildings and stone artwork. Acidity in rain is measured by collecting samples of rain and measuring its pH. To find the distribution of rain acidity, weather conditions are monitored and rain samples are collected at sites all over the country.

The areas of greatest acidity lowest pH values are located in the Northeastern United States. This pattern of high acidity is caused by the large number of cities, the dense population, and the concentration of power and industrial plants in the Northeast.

In addition, the prevailing wind direction brings storms and pollution to the Northeast from the Midwest, and dust from the soil and rocks in the Northeastern United States is less likely to neutralize acidity in the rain. When you hear or read in the media about the effects of acid rain, you are usually told about the lakes, fish, and trees in New England and Canada.

However, we are becoming aware of an additional concern: many of our historic buildings and monuments are located in the areas of highest acidity. In Europe, where buildings are much older and pollution levels have been ten times greater than in the United States, there is a growing awareness that pollution and acid rain are accelerating the deterioration of buildings and monuments. Stone weathers deteriorates as part of the normal geologic cycle through natural chemical, physical, and biological processes when it is exposed to the environment.

This weathering process, over hundreds of millions of years, turned the Appalachian Mountains from towering peaks as high as the Rockies to the rounded knobs we see today. Our concern is that air pollution, particularly in urban areas, may be accelerating the normal, natural rate of stone deterioration, so that we may prematurely lose buildings and sculptures of historic or cultural value.

This religious medieval sculpture, made of sandstone, has been degraded by the acidification of air and rains. Many buildings and monuments are made of stone, and many buildings use stone for decorative trim. Granite is now the most widely used stone for buildings, monuments, and bridges. Limestone is the second most used building stone. It was widely used before Portland cement became available in the early 19th century because of its uniform color and texture and because it could be easily carved.

Sandstone from local sources was commonly used in the Northeastern United States, especially before Nationwide, marble is used much less often than the other stone types, but it has been used for many buildings and monuments of historical significance. Because of their composition, some stones are more likely to be damaged by acidic deposition than others. Granite is primarily composed of silicate minerals, like feldspar and quartz, which are resistant to acid attack. Sandstone is also primarily composed of silica and is thus resistant.

A few sandstones are less resistant because they contain a carbonate cement that dissolves readily in weak acid. Limestone and marble are primarily composed of the mineral calcite calcium carbonate , which dissolves readily in weak acid; in fact, this characteristic is often used to identify the mineral calcite. Acid precipitation affects stone primarily in two ways: dissolution and alteration. When sulfurous, sulfuric, and nitric acids in polluted air react with the calcite in marble and limestone, the calcite dissolves.

In exposed areas of buildings and statues, we see roughened surfaces, removal of material, and loss of carved details. Stone surface material may be lost all over or only in spots that are more reactive. You might expect that sheltered areas of stone buildings and monuments would not be affected by acid precipitation. However, sheltered areas on limestone and marble buildings and monuments show blackened crusts that have spalled peeled off in some places, revealing crumbling stone beneath.

This black crust is primarily composed of gypsum, a mineral that forms from the reaction between calcite, water, and sulfuric acid. Gypsum is soluble in water ; although it can form anywhere on carbonate stone surfaces that are exposed to sulfur dioxide gas SO 2 , it is usually washed away. It remains only on protected surfaces that are not directly washed by the rain.

Gypsum is white, but the crystals form networks that trap particles of dirt and pollutants, so the crust looks black. Acid rain has many negative impacts on the environment. Acid rain can alter the pH of surface water such as lakes and streams stressing aquatic life that is adapted to certain pH levels.

Acid rain also can erode to concrete buildings and monuments. And the particles in acid rain can contribute to health problems for people with respiratory illness like asthma or bronchitis. Below are links that provide some good background information about water quality and pH and the impacts of acid rain.

You may ask students to do some of their own research as well. Acid Rain Impacts on the Environment. To do this you will be using data on pH levels collected from both lakes for the years and making two charts. You will be using these charts along with the charts provided in the lesson to answer the questions A-E. Although the charts will help you to answer some of the questions you will need to refer to the website links found at the bottom of the page for further information.

At the end of this lesson you should have completed:. In this activity you will make two charts showing a line graph of the average pH concentrations in the surface waters of a lake in the Adirondacks - Morehouse Lake, and for a lake in the Finger Lakes region - Seneca Lake, for the years Follow the steps below to complete the activity.

Step 1 Copy and paste to copy the data sets including the headers shown here into an Excel file. What is the general trend of the pH levels in the lakes over the past ten years? The general trend has been for the pH levels to increase. The magnitude of these increases may not seem apparent to the students when they view the charts and see only a unit increase in pH levels from one year to the next.

Remind students however that the increase in pH from one unit to the next is logarithmic or exponential. The articles enphasize that scientists are claiming the increase in pH levels are apparent but may not keep going up if there are not more restrictions placed on emissions from power plants and vehicles. How would you explain this trend? The increase in pH values over the past ten years has been linked to the Amendments to the Clean Air Act of Although scientists agree that the Amendments have helped reduce the impacts of sulfur dioxide emissions, they are unclear whether the Amendments have had as great an impact on Nitrogen Oxide emissions.

Scientists from Syracuse University and the University of Maine caution that further reductions in emissions may be needed to bring the lakes in the Northeast back to health. Which lake system has a greater potential to buffer the effects of acid rain and why?