Acid RainPollution comes in various forms. Whether it’s toxic waste, CFC’s, orsewage, they are all hazardous, to the earth.
These can deplete the earth andit’s inhabitants of resources, causing a harmful change. A product ofpollution is acid rain. We shall see that acidification is harmful to all formsof life. Acid rain is any form of precipitation that is polluted by sulphurdioxide (SO2), and nitrogen oxides (NOX). This acid precipitation can be in theform of rain, snow, sleet, fog, or cloud vapors.
The acidity of substancesdissolved in water are measured by their pH levels. Normal precipitation pHlevels fall between 5. 0-5. 6. 2 When levels fall below these numbers, then theprecipitation is said to be acidic. There are two ways in which acid depositioncan form.
The first way occurs when nitrogen oxides and sulphur dioxide land onthe Earth’s surface, and interact with frost or dew. The second way takesplace due to the oxidation of nitrogen oxides or sulphur dioxide gases that arereleased into the air. 3 Since it may take up to several days for the gases to bealtered into their acid counter-parts, the pollutants can travel miles away fromtheir original source. Emissions of (SO2) are responsible for the majority ofthe acid deposition, which falls to Earth.
When we burn coal, we are releasing(SO2), into the air, since coal is slight made up of sulphur. Volcanic eruptionscan add a great deal of sulphur into the atmosphere. Everyday organic decay addssulphur into the air as well. (SO2) can hit the Earth’s surface in dry formsor wet forms, by undergoing the following reactions: (SO2 + H20 *** H2SO3) (SO2+ ?O2 *** SO3 + H2SO4)2 Human activity is the major cause for nitrogenoxides’ presence in our atmosphere, such as forest fires and the combustion ofoil, coal, and gas. The other causes are due to nature. Lightning, volcanicaction, and bacteria in soil are just to name a few.
The following chemicalreactions show how acids of nitrogen form: (NO2 + ?O2 *** NO2) (2NO2 + H2O ***HNO2 + HNO3) (NO2 + OH *** HNO3)2 Acid rain can affect plant life directly whenthe surface of leaves and needles come into contact with acid vapor or fog. Thiscauses a reduction in the tree’s ability to withstand the cold. A directresult would be the tree’s incapability of reproduction. It can also harm plantlife indirectly, by the acidification of soils. Acid rain can cause soil toloose nutrients such as calcium, potassium, and magnesium.
In very acidconditions, aluminum becomes soluble, and is released from the soil. At highenough concentrations, aluminum can cause damage to roots. Acid rain causes anutrient imbalance, in soil. Although it is true that nitrogen promotes forestgrowth, plant life also needs other nutrients. Precipitation polluted bynitrogen can contain heavy metals, such as mercury, cadmium, and lead. Thisprocess is known as nitrogen saturation.
1 These too, can cause damage to treeroots. Besides trees, plants are also affected by acid rain. Reductions in pHlevels can cause seed germination to be inhibited. Plant structures become weak,due to the loss of nutrients to the plant’s tissues. 4 Flowering of certainplants may not occur due to lack of essential minerals. Marine life is alsogreatly affect by acid rain.
Acid water can leach high levels of aluminum fromthe bedrock. Rocks that contain great amounts of calcium or magnesium can act asa neutralizer. Those rocks and soils that lack some sort of buffers can causegrave damage to marine fish and plants. There are two ways in which aluminum canharm aquatic environments. It can cause a fish to suffocate, because aluminumprecipitates in gills, thus interfering in the transport of oxygen. Secondly,fish produce mucus to combat the aluminum, in their gills.
The mucus then buildsup a clogs the fish’s gills. 5 In middle latitudes many bodies of waterexperience what is called “acid shock. “4 Over the winter acid deposits canbuild up on snow. As the snow melts, the acids are released. Most fish cansurvive shock, but their eggs cannot adapt to acidification.
When there is achange in the chemistry of water, the ecology of the water begins to change. Thenumber and variety of species are altered. At a pH level of 6. 0 certain types ofzooplankton and green algae begin to disappear.
The loss of green plants allowsmore UV light to penetrate to further depths, so certain types of snails andphyto-plankton disappear. Frogs, toads, and salamanders are also affected byacid rain. 5 The low pH stunts their growth. Not only does acid rain killspecies, but also it alters the food supply for higher fauna.
If there is adecrease in the number of bottom dwelling organisms (benthos), there can be adecline in the number of insects, such as mosquitoes and flies. This puts astress on carnivorous fish. Birds that eat these fish, which may contain highlevels of aluminum, will then produce eggs with soft-shells. Their young willmost likely not survive.
Humans are not immune to the effects of acid rain. People that are exposed to high concentrations of acidic pollution are known tohave respiratory problems. SO2 can react with water vapor to form fine particlesof sulphate. If inhaled, these particles can cause severe damage to lung tissue. The affect can be a simple cough or chest cold, or as dangerous as asthma orchronic bronchitis.
Humans can consume aluminum by drinking water or eatingcrops that have contaminated by acid precipitation. If ingested in largequantities, it can have toxic effects on human health. Many doctors believe thataluminum consumption can lead to Alzheimer’s disease. 1 We see the effects ofacidification everyday.
All forms of acid precipitation may damage automotivecoatings. The damaged is mostly observed on newly painted vehicles. It is theevaporation of acidic moisture that causes the damage. Many headstones andbuildings and statues, such as the Statue of Liberty, are affected in the sameway.
Acid deposition can cause fading of these structures. Churches andcathedrals also suffer. 3 The United States is trying to take care of thisproblem through environmental legislation. Title IV of the Clean Air ActAmendments of 1990, calls for a 10 million ton reduction in the number ofemissions of sulfur dioxide. 3 One way of reducing emissions is lowering theproduction of sulphate aerosol cans.
Since this act was passed, hospitals havewitnessed a significantly lower number of cases of respiratory problems. Thereare other ways that we can alleviate the problems of acid deposition. A processknown as liming can increase the pH levels of bodies of water. 2 Large quantitiesof hydrated lime are added to the water. The best way to solve the problemscaused by acid deposition is for industries to try to limit the emissions ofpollutants.
There has been two ways in which industries have done this. Severalcompanies have switched to using fuels that have a low sulphur content. Otherindustries have used buffers on the tops of their smokestacks, to reduce theamount of (SO2) in the air. 4 There is no way that we can totally eliminate aciddeposition. We as humans, are not the only creators of this problem. Over theyears, there has been an increase in the amount of annual precipitation.
We canchange our ways of production to help decrease the amount of acid precipitation,but then that would be greatly affecting our way of life. More then the acidrain itself does. Just like the cycle of affects the acid rain has on aquaticand terrestrial systems, there is the same type of cycle viewed when it comes tohuman life.
