What is the average ph of rainwater in the us

Typical acid rain has a pH value of 4. A decrease in pH values from 5. There are many high-tech devices that are used to measure pH in laboratories.

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. Is Acid Rain Harmful to Animals? Does Rain Water Contain Nitrogen? How to Dissolve Silicate. Examples of Secondary Pollutants.

The Advantages of Acid Rain. How Is Rain Formed? Review - Acids and Bases The sulfuric and nitric acids formed from gaseous pollutants can easily make their way into the tiny cloud water droplets.

These sulfuric acid droplets are one component of the summertime haze in the eastern U. Some sulfuric acid is formed directly in the water droplets from the reaction of sulfur dioxide and hydrogen peroxide. Some of these sulfuric acid particles drop to the earth as "dry" acid deposition. The tiny water droplets containing sulfuric acid provide a ready surface to attract more molecules of water to form a larger droplet of dilute sulfuric acid.

Water droplets collected from the base of clouds in the Eastern U. The pH in the upper portion of a cloud is much higher. The final rain droplet has an average pH of 4.

In Los Angeles, the pH of fog has been measured at 2. Contrary View:.