Wednesday, April 11, 2012

Soil and Acid Rain


Acid rain can be very harmful to the environment. It can kill fish by lowering the pH of lakes and rivers. It can harm trees and plants by burning their leaves and depriving them of nutrients. In addition, it can weather away stone buildings and monuments. But why is it more of a problem in some places than others?

To answer this question, let’s first look at how rain becomes acidic. Carbon dioxide, CO2, is a gas found naturally in the air. When CO2 dissolves into rain droplets, it produces a weak acid called carbonic acid, H2CO3. This makes rain slightly acidic naturally. Rain of pH 5 to 6 is common and does not generally cause any problems. When fossil fuels are burned, however, gases such as sulfur dioxide, SO2, are released into the air. When sulfur dioxide dissolves into rain droplets, sulfuric acid, H2SO4, is formed. This rain can be as acidic as pH 4.

In this experiment, you will use a pH Sensor to measure the pH of acid rain. You will then allow the acid rain to filter through two different types of soil. The run-off will be collected and its pH retested to determine your soil’s buffering capacity.


In this experiment, you will

Use a pH Sensor to measure the pH of acid rain.
Use a pH Sensor to measure the change in pH as acid rain passes through soil.
Interpret your results.

Important facts on Acid Rain

Acid rain refers to any precipitation hence a pH value less than that of normal rain water, when pH value is around 5 or 6. Normal rain water is weakly acidic, because atmospheric carbon dioxide combines with rain water to form weak carbonic acid.

The severe acidic nature of water occurs due to massive pollution caused by industrialization. Oxides of sculpture, nitrogen and hydrocarbons are the major contributing factors to acid rain.

The gases and aerosols accumulate high up in the atmosphere, water vapors condense on aerosol surface and form a fine film providing suitable level as catalysts for the oxide of sculpture and nitrogen to dissolve in water and react to form corresponding acids which form salts such as nitrates and sulphates when come in contact with basic aerosols. As water vapors continue to condense on these aerosols, large droplets of water are produced which rain down as acid rains.

Sulphuric acid, nitric acid and various sulphates and nitrates are the major chemical constituents of acid rain, small amount of hydrochloric acid and its salt may also be present.

Most areas are susceptible to acid rain. The buffering capacity of water or soil determines its susceptibility. In general, lower the buffering capacity of soil or water is produced which rain down as acid rains.

Oxides of Sulphur :

Oxides of sulphur mainly sulphur dioxide with second most important pollutant of the atmosphere is obtained from burning of organic matter, fossil fuels and from industries - usually oxides of sulphur dissolve in the water and are carried out down the earth with rain.

The pressure of sulphur dioxide in the* atmosphere causes a wide variety of harmful effects on plants and animals. Plants when exposed for a long time, sulphur damage to chloroplasts.

Acid Rain

The term ‘acid rain’ means any form of precipitation like rain, fog, snow, or hail that contains harmful substances such as nitrogen and sulfur oxides. The major human sources do come from the industry, transportation, and a variety of power plants. Strictly speaking these industrial amounts of nitrogen, sulfur oxides and general pollutants from the air cause a drastic increase of the acidity of the precipitation and do also harm plants, humans, and buildings.

In order to save the climate and to protect the general air quality the Air Pollution & Climate Secretariat, formerly known as the Swedish NGO Secretariat in Acid Rain, tries to promote awareness of the variety of problems being associated with air pollution. Strictly speaking the Air Pollution & Climate Secretariat is a joint venture between five Swedish environmental organizations. This secretariat operates with the chief purpose to achieve the required reduction of the emission of air and industrial pollutants, including greenhouse gases. Consequently those emissions should be brought down to a level that our environment and nature are able to tolerate without suffering any damage regarding plants, buildings, and humans.

Fact is that air pollution affects both humans and the nature. Most obvious are the so-called direct effects on human health. Results of recent research show that small particles in the air caused more than 350,000 premature deaths within the 25 countries of the European Union in 2000. Furthermore it has to be taken into consideration that there are also other air pollutants as well as indirect effects on nature and humans. Those indirect effects include effects such as toxic groundwater and corrosion of materials. Many people use so-called blinds and/or marquees, also called Markisen in German, in order to protect for instance their terrace or patio from polluted air particles.

Due to drastic air pollution and the worsening of the general air quality, the climate does also get affected. If the climate gets warmer it affects a human’s health. A number of researchers fear that a warmer climate in the course of a general climate change may cause more extreme weather conditions. Strictly speaking this would also lead to more injuries and deaths being caused by hurricanes, flooding as well as to property damage. Another effect resulting from a warmer climate is the spread of a variety of insect transmitted diseases such as malaria and bilharzias.

Eco Friendly Cleaning

You want to protect the environment and you are of the opinion that we all on earth have to make a contribution to this procedure? Then you should read this article focusing the topic of eco friendly cleaning. Fact is that the protection of the environment has to start within our own four walls in order to reach successful results. Strictly speaking there exists a variety of interesting eco friendly ways to clean houses and buildings. So we want to inform you about environmentally friendly substances, measures and ways that have turned out to be extremely effective when it comes to house cleaning in general – a process that is also communicated by means of the two terms ‘Gebäudereinigung’ as well as ‘Gebäudereinigung Köln’ (relating to cleaning methods in big cities such as Köln, Berlin, Vienna, etc.).

First of all it is important to mention that environmentally friendly cleaning products and substances which are naturally based on selected citrus solutions as well as essential oils should be first class. In this case we are talking about products and substances that do also feature trusted and high quality ingredients such as for instance vinegar. Furthermore it can be said that these environmentally friendly products are basically used with so-called old-fashioned ‘elbow grease’ in order to generate a real shine.

Please mind that you do not have to do all the cleaning on your own. Fact is that there exists a variety of different and interesting environmentally friendly cleaning services that would definitely be happy to come and support you in doing an excellent cleaning job.

Moreover it is strongly recommended to replace toxic cleaning products. Consequently you should always choose non-toxic as well as biodegradable substitutes in order to help reduce both the toxic burden and the waste steam in your home.

Besides you should also learn so-called non-toxic cleaning basics, in particular how to make use of a variety of different kitchen cupboard ingredients. Strictly speaking it turns out to be important to learn how to make homemade recipes in order to save money and protect your health. Hence it is also possible to reduce the general use of valuable resources of our earth by avoiding both petroleum products and substances and other non-renewable resources.

Before buying any cleaning products, please make sure that these substances are totally free from harmful chemicals. So it is important to check and consequently know that none of your cleaning products contain petrochemicals, ammonia, anything toxic, bleach, neurotoxin or carcinogenic. Fact is that cleaning products that contain only one of these already mentioned ingredients are harmful to us as well as the whole environment.

The Chemistry of Acid Rain

The Chemistry of Acid Rain

Key Concepts

Rain from an unpolluted atmosphere has a pH close to 6.0 (slightly acidic).

This acidity is due to the reaction of water vapour and non-metal oxides in the atmosphere, such as carbon dioxide and nitrogen oxide, forming dilute acids.

  • carbon dioxide reacts with water to form carbonic acid:
    CO2(g) + H2O(l) H2CO3(aq)

    Since carbonic acid is a weak acid it partially dissociates:

    CO2(g) + H2O(l) H+(aq) + HCO3-(aq)
  • nitrogen dioxide reacts with water to form a mixture of nitrous acid and nitric acid:
    2NO2(g) + H2O(l) HNO2(aq) + HNO3(aq)

Acid rain has a pH below 5.6 due mainly to the reaction of water vapour with sulfur dioxide and the oxides of nitrogen.

  • Sulfur dioxide reacts with water to form sulfurous acid (H2SO3):
    SO2(g) + H2O(l) H2SO3(aq)

    Sulfur dioxide (SO2) can be oxidised gradually to sulfur trioxide (SO3):
    2SO2(g) + O2(g) -----> 2SO3(g)

    Sulfur trioxide (SO3) reacts with water to form sulfuric acid (H2SO4):
    SO3(g) + H2O(l) -----> H2SO4(aq)
  • Oxides of nitrogen, particularly nitrogen dioxide (NO2) react with water to form nitrous acid (HNO2) and nitric acid (HNO3):
    2NO2(g) + H2O(l) -----> HNO2(aq) + HNO3(aq)

Sources of the acids in clean and polluted air

AcidClean airPolluted air
Carbonic acid


natural carbon dioxide (CO2)
produced during plant and animal respiration
produced during decomposition of organic matter
Carbon dioxide (CO2) released from the combustion of fuels
The complete combustion of coal:
C(s) + O2(g) ---> CO2(g)
The complete combustion of petrol (for example octane, C8H18(l)):
Complete combustion of ethanol (ethyl alcohol):

Formic acid (Methanoic acid)


Oxidation of natural methane (CH4) formed during the anaerobic decomposition of organic matterIncreased oxidation

Sulfuric acid (Sulphuric acid)


Natural decay of organic matter releases hydrogen sulfide gas (H2S) which can be oxidised to sulfur dioxide (SO2):
Sulfur dioxide can be oxidised to sulfur trioxide (SO3):
Sulfur trioxide then reacts with water to form sulfuric acid:
Volcanoes emit sulfur dioxide which can be oxidised to sulfur trioxide which then reacts with water forming sulfuric acid.
Ocean algae release sulfur gases such as dimethyl sulfide which is oxidised to form sulfuric acid.
Combustion of coal and other fossil fuels account for about 80% of the man-made sulfur dioxide in the atmosphere (sulfur is present in the proteins of the original living matter that has been fossilised to produce the fossil fuel such as coal, oil or petroleum). Most of this is from coal-fired power stations, motor vehicle emmissions account for only about 1% of the sulfur dioxide present.
Sulfur dioxide is also produced when sulfur ores are roasted:
Sulfur dioxide is also produced in the manufacture of sulfuric acid by the contact process, in petroleum refining and in the manufacture of coke from coal

Nitric acid


Lightning flashes lead to a reaction between atmospheric nitrogen and oxygen in the presence of water vapour which forms nitric acidCombustion of fossil fuels
Nitric oxide (nitrogen monoxide, NO) is produced in internal combustion engines as a result of the reaction between oxygen and nitrogen at high temperatures:
Nitrogen monoxide is readily oxidised to nitrogen dioxide (NO2):
Nitrogen dioxide reacts with water to form nitrous acid (HNO2) and nitric acid (HNO3):

Methanesulfonic acid

(Methanesulphonic acid)

Ocean algae emit dimethyl sulfide which oxidises in air to produce methanesulfonic acid.methanesulfonic acid is only produced naturally

Effects of Acid Rain

Acid rain is a form of environmental pollution that damages buildings and marble statues by reacting with the calcium carbonate to form soluble calcium hydrogen carbonate (calcium bicarbonate, Ca(HCO3)2)

CaCO3 + acid rain -----> Ca(HCO3)2(aq)

Acid rain can leach aluminium from the soil into ground water, lakes and rivers, poisoning fish and plant roots.

The sulfates and hydrogen sulfates in acid rain can can leach essential plant nutrients such as calcium and magnesium, from the soil.

Acid rain disrupts the process of photosynthesis resulting in damage to plant life.

At low concentrations it retards the production of chlorophyll and at high concentrations it forms sulfuric acid which kills the plant.

Some organisms are sensitive to changes of acidity in water which can affect their ability to reproduce and in some cases may kill them.