Acid rain is not just rain as the name would suggest, but any form of precipitation with acidic levels below, as a guideline, 5.6pH (remember the lower the pH, the greater the acidity). 5.
6pH is given as a guideline because this would be the pH of carbonic acid rain in average CO2 air conditions. However there are other gases that cause different types of acid rain, and some cause lower pH levels than this. This is why most people have now ditched the ‘5.6 or lower pH is acid rain’ concept. In actuality, acid rain is rain with a pH that is unusually low compared to it’s surrounding because it has acid in it.
Acid rain is caused by water in any state (solid, liquid or gas) picking up gases such as nitrous oxide, carbon dioxide and sulphur dioxide in any stage of the hydrological cycle. What matters is that as the acidic gases come into contact with the water and the two compounds become a mixture that is a dilute liquid acid. The amount of acidic gas the water picks up affects the acidity of the acid rain. There is more to this however, if an alkaline base is present in the water and all the acid is completely neutralized, though acid was in the rain, it cannot be called ‘acid rain’. Here are the summarized characteristics that make acid rain, acid rain.* It must be acidic* There must be (an) un-reacted gas(es) present* It must be an acid dilute in water* It must be corrosiveThe last point there shows that acid rain is capable of damaging buildings and life-forms. It is this that makes acid rain a danger and this is why we want to minimize this. True, there is little stopping the natural causes, such as volcanoes and decaying matter, causing acid rain, but this is nothing compared to what we have done.
Occasional acid rain in rivers and other aqueous habitats may cause a sudden drop in the amount of wildlife when it occurs, but the ecosystem soon replenishes itself. This happens often in nature where an unusual occurrence is soon righted. However, if something such as this persists it could mean wiping out the whole ecosystem (killing those at the bottom of the food chain affects all involved in the food chain), even non-aquatic creatures such as fish-eating birds. That is if the acid-concentration is high enough to kill any life-forms.
If it isn’t, but persists then mutations such as that of the frog on the left could occur, and though those above the frog in the food chain can eat these frogs, these mutated frogs continue to form and eventually all the ‘normal frogs’ have developed mutations which normally are unhelpful and so a species dies out. This also greatly damages ecosystems, even with only a tiny amount of acid.Most plants are not affected directly by acid rain. A moderate/weak acid does not affect the leaves, roots, or stems of most plants.
What damages these plants is caused by the effects acid rain has on the soil. Acid rain in the soil dissolves nutrients the plant needs (such as potassium for plant growth and cell re-generation) depriving the plant, slowly becoming sicker, until it dies. If acid rain levels are incredibly high, whole forests can be wiped out, and this is becoming increasingly common. Deforestation levels are already too high for re-planting to overcome this, and on top of the trees we already destroy to make textiles and materials, whole forests are dying due to our actions and we are not even using these trees.
We need to act now, as acid rain is either directly or indirectly damaging almost all types of life-form on the Earth. It seems that emissions need to be dealt with so they do not get into the atmosphere at all, whether to stop Global Warming, Pollution, the depletion of the Ozone Layer or Acid Rain. One of the simplest and cheapest ideas so far would be to ‘water-down’ these gases so they form dilute acids (like acid rain) which are somehow drained away. As long as the gases are contained as acids in water they can cause very little harm to the atmosphere, and we would be able to dispose of these acids rather than having the acidic gases lose in the air, waiting for acid rain to wreck its havoc.