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. Eventually the black crusts blister and spall off, revealing crumbling stone. Want to learn more about acid rain and water? Follow me to the Acid Rain website! The USGS has been at the forefront of studying the impacts of acid rain for decades.
How does acid rain form? What does it do to the landscape? Can it burn you like battery acid? Keep reading to find out more Water is everywhere, which is fortunate for all of humanity, as water is essential for life.
Even though water is not always available in the needed quantity and quality for all people everywhere, people have learned to get and use water for all of their water needs, from drinking, cleaning, irrigating crops, producing electricity, and for just having fun.
The U. When scientists learned that acid rain could harm fish, fear of damage to our natural environment from acid rain concerned the American public. Research by USGS scientists and other groups began to show that the processes resulting in acid rain are very One of the goals of research on the effects of acidic deposition on carbonate stone surfaces is to define the incremental impact of acidic deposition relative to natural weathering processes on the rate of carbonate stone erosion.
If rain that impacts carbonate stone surfaces is resident on the surface long enough to approach chemical equilibrium Review of: The acid rain controversy, by Regens, J. Skip to main content. Share Tweet Email. Why it's so hard to treat pain in infants. This wild African cat has adapted to life in a big city.
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Acid rain itself is not harmful to humans , ie, the skin contact with contaminated water or snow does not pose a health risk. However, the gases that cause this rain nitrogen oxides, sulfur dioxide and sulfur trioxide , are harmful. These gases contain particles of sulfate and nitrate and are carried by the wind and inhaled by people causing respiratory diseases. The only way to stop acid rain is to reduce emissions that cause it. This involves betting on renewable energy sources and reducing the use of fossil fuels in the industrial and automotive sector and in the daily life of every citizen.
The following infographic might help better understand what acid rain is and what are its effects :. How can it affect people?
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