In detail

Acid rain


What is acid rain? Definition and simple explanation:

As acid rain are precipitates which have a lower pH than about 5.5 due to the action of various chemical substances. Rain is mainly caused by the absorption of nitrogen and sulfur dioxide (see also acids), which are released as by-products during the combustion of fossil fuels in heating systems and vehicles. Acid rain is one of the main causes of forest dying because it damages plants directly and changes their growth conditions through a chemical change in soils.

Causes of acid rain

In the course of combustion of sulfur-containing energy sources such as oil, natural gas or coal, sulfur oxides and nitrogen are released into the air. The increase in households and growing traffic and industry are also increasing the quantities of these chemicals. Sulfur dioxide combines in the atmosphere with other substances and forms various acids, especially nitric and sulfuric acid. In the atmosphere, the sulphurous acids are absorbed by the rain, but also by snow, hail and fog and reach the ground where they seep into the soil and settle on the leaves of the plants.

Effects of acid rain on the environment

Large-scale forest damage is in many cases due to the action of sulphurous acids. If they get into the soil, they change the chemical balance that gives the plants their livelihood. The acidification of the soils primarily alters the delicate nutrient composition and water balance, causing damage to the fine roots of the trees. Above all, the release of aluminum and heavy metals are responsible for the mass extinction of the plants. They affect the natural functions of the fine roots and fungal plexus surrounding them. As a result, the trees can no longer or only to a limited extent absorb vital nutrients. The resulting nutrient deficit leads in the long term to the tree losing its resistance and becoming vulnerable to disease and external influences.
Not only pests such as bark beetles and fungal diseases have easy play with the weakened trees. The nutrient deficiency also makes the tissue more sensitive and dries out. This is due to the direct action of the acids contained in the rain, which adhere to the leaves and needles and affect the function of the so-called stomata there. If they can no longer close due to the deposition of the acids, a gap-opening rigidity occurs. The tree can no longer store moisture inside and gradually dries up. A storm or storm can quickly lead to significant damage to the trunk and branches in such a diseased tree, as the substance is porous and brittle.
While acid rain in plants can lead to different diseases and cause the death of entire forests, also waters and the animals living in them are severely damaged by its action. The altered pH leads to a dissolution of calcareous casings and shells of molluscs, also changes the growth conditions of plants in water and deprives many animals of their food source. Therefore, the acid rain is associated not only with the forest dying, but also with a reduction in biodiversity. In addition, the rapid weathering of buildings is also due to the action of acid rain.

Measures against the acid rain

In regions where there are large deposits of calcareous rock, the effects are significantly lower because lime largely neutralizes the acids. As a result, large amounts of lime are being scattered in many European countries today to protect the landscape from acidification. Nevertheless, it is essential to drastically reduce the emission of toxins, which is mainly ensured by the installation of filter systems in industrial heating systems and vehicles. The decommissioning of power plants that use fossil fuels to generate electricity, the use of renewable energies and the sparing use of energy in general are important measures in the fight against the acidification of the environment.