Why Does Acid Rain Erode Marble

Acid precipitation affects stone primarily in two ways.

Why does acid rain erode marble. Acid rain s ability to dissolve marble and limestone makes it hazardous to buildings and outdoor monuments. In exposed areas of buildings and statues we see roughened surfaces removal of material and loss of carved details. How does acid precipitation affect marble and limestone buildings. Erosion due to dissolution.

Acid rain effects on buildings. It is well established that either wet or dry deposition of sulfur dioxide significantly increases the rate of corrosion on limestone sandstone and marble. During the past several years research in the effects of acidic deposition on carbonate stone has been conducted under the national acid precipitation assessment program napap 2 to define the incremental effect of acidic deposition under ambient environmental conditions. Sulfur dioxide plus water makes sulfurous acid.

Or if there is more acid two hydrogen ions will. Acid rain is a byproduct of both natural and man made conditions. Limestone is mostly made up of the mineral calcium carbonate caco3. But if you add an acid you add hydrogen ions h which will react with the carbonate to form hydrogen carbonate hco3 ions which are very soluble in water and the limestone will dissolve.

When sulfurous sulfuric and nitric acids in polluted air and rain react with the calcite in marble and limestone the calcite dissolves. Igneous and metamorphic rocks exposed to acid rain can poison ecosystems. Acids have a corrosive effect on limestone or marble buildings or sculptures. Field investigations of acidic deposition effects on limestone and marble.

Marble is mainly calcium carbonate. Acid rain contains carbonic nitric and sulfuric acid that are produced by oxidation and dissolution in water of gaseous oxides co 2 no 2 and so 2 present in the air as chemical pollutants. Acid rain is composed of sulfuric acid h2so4 or nitric acid hno3 formed as secondary pollutants from so2 other sulfur oxides and nitrogen monoxide no. This is not very soluble so rocks don t dissolve very quickly.

The precursors or chemical forerunners of acid rain formation result from both natural sources such as volcanoes and decaying vegetation and man made sources primarily emissions of sulfur dioxide so 2 and nitrogen oxides no x resulting from fossil. Stone such as granite and gneiss release toxic aluminum ions into the environment when exposed to acid rain. In the atmosphere rain mixes with carbon dioxide nitrous oxide and sulfuric dioxide to form acid rain. Marble like all calcareous rocks is particularly sensitive to degradation by acid chemicals and to weathering.

Stone surface material may be lost all over or only in spots that are more reactive. When sulfurous sulfuric and nitric acids in polluted air react with the calcite in marble and limestone the calcite dissolves.