Acid rain is caused by extra amounts of sulphur dioxide and nitrogen oxides. Natural sources of sulphur oxides and nitrogen oxides do exist, but are balanced by nature. Normal rain reacts with alkaline chemicals from the region’s bedrock that are in the air, soils, lakes, and streams. This neutralizes the rain. However, if rain is more highly acidic, then the natural neutralizing chemicals can eventually become depleted. This is what is happening with more than 90% of the sulphur and 95% of the nitrogen emissions coming from humans.
Approximately 40% of the nitrogen oxides come from transportation, about 25% from thermoelectric generating stations, and the balance from other industrial, commercial, and residential combustion processes. These pollutants come from the use of coal in the production of electricity, from smelting, and from the internal combustion engines in most cars. Once released into the atmosphere, they are converted into such pollutants as nitric acid and sulfuric acid, both dissolving easily in water. This results in acidic water droplets that can be carried by prevailing winds, returning to Earth as acid rain, snow, or fog.
This effects the lakes by changing the pH balance. As the water pH approaches 6, crustaceans, insects, and plankton begin to disappear. When the pH is slightly above 5, major changes start to happen, less desirable species of mosses and plankton may begin to flourish, whereas others will lessen in numbers and die off. Below pH of 5, the water is to acidic for many fish, the bottom is covered with undecayed material, and the shores may be dominated by mosses.
Animals also are affected. Some ducks, for example, depend on fish and other organisms for nourishment and nutrients. As these food sources are reduced or eliminated, the population in that area declines and the reproductive success of the birds is affected.
Plants are effected too. The acids can alter the protective waxy surface of leaves, lowering disease resistance. It also may slow down or stop plant germination and reproduction. The acids will accelerate soil weathering and removal of nutrients, which the plant need. And it will make some metals more soluble, for example, aluminum will be come high in concentration in the soil and clog the roots of the plants, stopping the intake of vital nutrients.
These are all good reasons we must be looking for new means of energy, in the very near future.
The Green House Effect
The atmosphere contains gases, such as carbon dioxide, nitrous oxide, methane, and water vapor that trap heat from the sun and reflect it back to earth. This process is called the Green House effect. Without the green house effect the earth would freeze. These gases have remand balanced for thousands of years, but today with the increased consumption of fossil fuels the balance is being upset. Now instead of freezing with too little gases the opposite is happening. The increasing gases are causing a gradual increase in temperature. Warming the earth over 100s of years. This rise in temperature will melt the polar ice caps causing many coastal lands to go under water. Also the climate in many areas will be effected. Southern Canada and the Northern U.S will be come a desert like climate whereas northern Canada will be that of a tropical climate.
The earths atmosphere has 3 layers, the troposphere, stratosphere, and ionosphere. In the stratosphere at 10-30 kilometers above the Earth’s surface there is a layer of ozone (03) that protects the earth from the sun’s harmful UV radiation. It forms a natural screen, which filters the light from the sun. Some chemicals, mainly CFCs, can break down the ozone and thin this protective layer, when present into stratosphere. One CFC can breaks down a molecule of ozone, and not be effected itself. This allows a single molecule of CFC to stay in the stratosphere for 40 years destroying molecules of ozone. If enough ozone is destroyed, holes will begin to form, as seen over Antarctica and the Arctic.
The amount of ozone in the stratosphere at any one time is subject to natural variation caused by sunspots, volcanic activity and atmospheric patterns. For example in areas of volcanic out gassing the ozone is decreases.
The past 15 years show significant decreases in the ozone layer. This is allowing harmful UV radiation through to us. Now more than ever sunscreen is needed.