The Effects Cemetery Stones: Acid Rain
The effect of acid rain on cemetery stones is clear enough that it has been used as an indicator of how much acid rain falls in a region. Sulfur dioxide and nitrogen dioxide are released into the atmosphere through natural processes, such as volcanoes and decomposition, but are also produced by burning fossil fuels.
Acid rain also happens through dry deposition, where the pollutants get stuck in smoke and dust and stick to surfaces, where they react to form acid the next time the surface gets wet. The first is whether it is possible to carve an inscription into the rock; the second is how enduring the rock will be as a monument; third is the aesthetic appeal of the final monument. Available options over the past few centuries are sandstone, limestone, marble, slate and granite. Sandstone and limestone are sedimentary rocks, while marble, slate and granite are harder metamorphic rocks.Limestone and marble are made up of calcium carbonate, making them susceptible to acid rain weathering. The hydrogen and nitrate or sulfate ions from acid rain react with calcium and carbonate ions.
The carbonate atom reacts with water to form bicarbonate, which reacts further with the hydrogen ions from the acid to create water and carbon dioxide gas.
The reaction leaves calcium and nitrate or sulfate ions, which wash away. This is a natural process because the calcium carbonate they are made of is slightly soluble in water. Acid rain speeds weathering through its chemical reaction with calcium carbonate.
Dissolving Limestone Rocks In Hydrochloric Acid (Fossils)
I experiment with hydrochloric acid(HCL) and sulphuric acid(H2SO4) in dissolving a stone sample. I expect to try this method on …
Marble resists acid rain slightly more than limestone because its structure is more densely packed. She was once charged by a grizzly bear while on the job. Not all lakes are equally affected by acid rain; the damage depends on the kind of bedrock present. Limestone neutralizes acids and has a buffering effect, but granite, composed of silicates, does not undergo any acid-base reaction. So a lake surrounded by granite rock is likely to suffer more damage from acid rain. But granite’s lack of reaction with acid also means that gravestone made of granite are going to last longer than those made of limestone. So a lake surrounded by granite rock is likely to suffer more damage from acid rain .’; consider granite does not undergo any acid-base reaction why it is likely to suffer more damage from acid rain? Its lack of reaction means that it won’t be weathered much by acid in rain. A lake surrounded by granite rock is likely to suffer more damage from acid rain because the granite is composed of silicates and does not undergo any acid-base reaction. Therefore it will not buffer acid rain like limestone will. Granite’s lack of reaction with acid also means that gravestone made of granite are going to last longer than those made of limestone. That is does it include the container for the water or is it just the water? The chemicals fall to earth as acid rain. Of all the building stones, granite is the least susceptible to acid rain because its composition is of feldspar and quartz, both of which resist attacks of acid. Acid rain is slowly destroying once-resistant granite. Oporto granite is beginning to show effects from acid rain, as many historical buildings and statues in the city are beginning to deteriorate. The acid rain deteriorates the cement and adjacent seams become pooling areas.
Intense pollution creates a thin black crust on the facades of stone buildings, including those made of granite. The highly trafficked area and canyon-like placement of buildings, plus the salty winds coming in from the sea and the acid rain combine to intensify the weathering of some of the most prominent buildings in the city. The position of the stone within the graveyard directly affects its deterioration. Deterioration is more prevalent in coarse-grained granites that are roughly polished. The dips and crevasses harbor trapped pollutants.
The longer the acid rain sits on the granite, the more quickly it deteriorates the stone. The water and its inhabitants are untouched by the effects of the acid rain.
Granite and Limestone
Many lakes surrounded by granite rock maintain a high acidic level because the granite does not neutralize the acid, and the low alkaline levels contribute to the killing of fish and living organisms.
The damage that occurs to ecosystems from acidic deposition is dependent on the buffering ability of that ecosystem. This buffering ability is dependent on a number of factors, the two major ones being soil chemistry and the inherent ecosystem sensitivity to acidification. Indirect damage to ecosystems is largely caused by changes in the soil chemistry. Increasing soil acidity can affect micro-organisms which break down organic matter into nutrient form for plants to take up. Increasing soil acidity also allows aluminium (a common constituent of soil minerals) to come into solution. In its free organic form, aluminium is toxic to plant roots and can lock up phosphate, thereby reducing the concentrations of this important plant nutrient. Soils containing calcium and limestone are more able to neutralise sulphuric and nitric acid depositions than a thin layer of sand or gravel with a granite base. If the soil is rich in limestone or if the underlying bedrock is either composed of limestone or marble, then the acid rain may be neutralised. Granite has no neutralising effect on acid rainwater. Therefore over time more and more acid precipitation accumulates in lakes and ponds.
The water bodies most susceptible to change due to acid precipitation are those whose catchments have shallow soil cover and poorly weathering bedrock, for example granite and quartzite. These soil types are characterised by the absence of carbonates that could neutralise acidity. The run-off water from such areas is less buffered than from areas such as limestone catchments, with an adequate level of carbonate. Such catchments and waters are termed acid-sensitive (poorly buffered), and can suffer serious ecological damage due to artificially acidified precipitation from air masses downwind of major emissions.
These areas are vulnerable because of their high elevations, small watersheds, and naturally acidic soils.
Different types of bedrock contain variable amounts of alkaline chemicals.
Regions with bedrock containing less alkali have a lower capacity for reducing acidity, and thus are more sensitive to acid deposition. To grow, trees need healthy soil to develop in.
Acid rain is absorbed into the soil making it virtually impossible for these trees to survive. As a result of this, trees are more susceptible to viruses, fungi and insect pests.
Long-term changes in the chemistry of some sensitive soils may have already occurred as a result of acid rain. As acid rain moves through the soils, it can strip away vital plant nutrients through chemical reactions, thus posing a potential threat to future forest productivity. Poisonous metals such as aluminium, cadmium and mercury, are leached from soils through reacting with acids.
This happens because these metals are bound to the soil under normal conditions, but the added dissolving action of hydrogen ions causes rocks and small-bound soil particles to break down. Plant life in areas where acid rain is common may grow more slowly or die as a result of soil acidification. There has also been noted a reduced amount of growth in existing trees as measured by the size of growth rings of the trees in these areas.
These effects occur because acid rain leaches many of the existing soil nutrients from the soil. The number of micro-organisms present in the soil also decreases as the soil becomes more acidic. This further depletes the amount of nutrients available to plant life because the micro-organisms play an important role in releasing nutrients from decaying organic material.In addition, the roots of plants trying to survive in acidic soil may be damaged directly by the acids present. Finally, if the plant life does not die from these effects, then it may be weakened enough so that it will be more susceptible to disease or other harsh environmental influences like cold winters or high winds.
Some regions cope with acidification better than others, having larger ‘critical loads’. Scientists determine critical load by examining rock and soil type, land use and rainfall. The terrain can withstand moderately large additions of acidity without undue suffering. If coniferous forests predominate, or if land is devoted to rough grazing, the result is a low critical load.
Acid Rain Eating Washington, D.C.
Acid rain damage can be seen on many of the monuments in Washington, D.C.. James Williams takes a tour.
Even minor acid deposition is undesirable. Chemical data are available from a few specific sites, from a small number of regional studies and from three national studies.
One of the lakes was healthy (basic), another was acidic, and the third cycled back and forth from basic to acidic. Water drains from the surrounding land into a lake. Water from rain and snow comes into contact with materials surrounding the lake before it drains into the lake. The layers of decaying leaves, called humus, are rich in organic matter and produce acids similar to vinegar. A lake may contain bicarbonate and other basic ions derived from rock weathering. These natural bases can neutralize acids present from the rain, snow, or soil. Rocks which contain limestone contain bases.
Rocks which contain granite contain very little bases.
In the graphic on the left, the location is given for lakes which are sensitive to acid rain. A lake with a high value of alkalinity is protected against acid rain. A lake with a low or zero value of alkalinity will most likely be effected by acid rain.To predict whether a lake will become acidic is based on a number of factors which may not be known. How fast are the bases replenished by weathering? How much acid is reaching the lake, both from the acid rain, snow, or natural decay of organic matter? The evidence is that alkalinity has been replaced by sulfate ions in many lakes.
Average lakes have lost 40 % of their alkalinity. Some sensitive waters have lost all alkalinity. When sulfurous, sulfuric, and nitric acids in polluted air and rain 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 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. It remains only on protected surfaces that are not directly washed by the rain. The brown stain is from a large amount of iron in your water. It is closely related to simple rust you see on metal, which is iron oxide. The source of the water you use probably is groundwater, and the water has filtered through rocks containing iron-rich minerals on the way to the well. Once in a while you get a glass of water, and it looks cloudy; maybe milky is a better term. Like any bubbles, the air rises to the top of the water and goes into the air, clearing up the water. A frequent cause of musty, earthy odors, especially toward the end of the summer, is naturally occurring organic compounds derived from the decay of plant material in lakes and reservoirs.
The odors can be objectionable, but generally are not harmful to health. Plants naturally grow in and around lakes, but sometimes lakes and ponds can get an overgrowth of plants, algae, or bacteria. Chemicals that are used on lawns and in agriculture (like nitrogen and potassium) wash into our water systems.
How Does Acid Precipitation Affect Marble and Limestone Buildings
Mine drainage is formed when pyrite, an iron sulfide, is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage. Prevailing winds transport the acidic compounds hundreds of miles, often across state and national borders.
Constructed of marble, the building took 11 years to complete. Constructed of marble, the building took 5 years to complete. List two or more ways that you could test the acidity of a sample of rainwater. Write a balanced chemical equation for the dissociation of nitric acid in water. What about the other 75% of the acidity of rain? One strategy for limiting the amount of acid pollution in the atmosphere is scrubbing. Write a balanced chemical equation for this reaction. Using these facts, you can deduce the formula for calcium sulfite.) b. How much sulfur dioxide (in moles) is prevented from entering the atmosphere when this much calcium sulfite is generated? A slurry is a thick suspension of an insoluble precipitate in water. Many lakes have become so acidic that fish cannot live in them anymore. Atmospheric pollutants are easily moved by wind currents, so acid-rain effects are felt far from where pollutants are generated. Limestone consists of smaller crystals and is more porous than marble; it is used more extensively in buildings.
Marble, with its larger crystals and smaller pores, can attain a high polish and is thus preferred for monuments and statues.
Although these are recognized as highly durable materials, buildings and outdoor monuments made of marble and limestone are now being gradually eroded away by acid rain. The degree of damage is determined not only by the acidity of the rainwater, but also by the amount of water flow that a region of the surface receives.
Regions exposed to direct downpour of acid rain are highly susceptible to erosion, but regions that are more sheltered from water flow (such as under eaves and overhangs of limestone buildings) are much better preserved. Gypsum is soluble in water, so it is washed away from areas that receive a heavy flow of rain. This results in blackening of the surfaces where gypsum accumulates.
An even more serious situation arises when water containing calcium and sulfate ions penetrates the stone’s pores.When the water dries, the ions form salt crystals within the pore system. These crystals can disrupt the crystalline arrangement of the atoms in the stone, causing the fundamental structure of the stone to be disturbed. If the crystalline structure is disrupted sufficiently, the stone may actually crack. Thus, porosity is an important factor in determining a stone’s durability. Also, in the structure of the carbonate ion, are any of the oxygens bonded to one another, or all the oxygens bonded to the carbon atom? Write the net ionic equation for the reaction of calcium carbonate and sulfuric acid. Which is a more durable building material, limestone or marble?