Lichen's Superpower: Unveiling Air Pollutants

Lichens are composite organisms that combine fungi, algae, and cyanobacteria. They are highly sensitive to air pollution, making them excellent bioindicators of air quality. Lichens absorb nutrients from the air and are unable to filter out pollutants, which can quickly become toxic to them. As a result, the presence or absence of lichens, as well as their variety and size, can indicate the level of air pollution in an area. Lichens are also used in biomonitoring to assess the sustainability of ecosystems, including air quality, by measuring the concentrations of pollutants in their tissue.

Lichens are sensitive to sulphur dioxide and nitrogen in the air

Lichens are highly sensitive to sulphur dioxide and nitrogen in the air, which are two of the main air pollutants that affect their growth. Sulphur dioxide, a product of coal burning and industry, can be easily absorbed by lichens, disrupting important physiological processes. It has an acidifying effect once dissolved in the cellular cytoplasm, impairing enzyme-mediated processes like photosynthesis and respiration. As a result, sulphur dioxide exposure leads to a decline in lichen diversity as sensitive species are lost without being replaced.

Lichens are also very responsive to nitrogen, which is an essential nutrient for all living organisms. They obtain nitrogen from various atmospheric sources, such as ammonium, nitrate, and nitric acid dissolved in precipitation or through direct dry deposition of nitrogen-containing gases and particles. The presence of certain nitrogen-loving lichen species, such as *Candelaria concolor*, *Physcia adscendens*, and *Xanthoria polycarpa*, indicates elevated nitrogen deposition, either from natural or anthropogenic sources.

The sensitivity of lichens to these pollutants makes them excellent bioindicators of air quality and environmental health. By studying their presence, distribution, and physiological responses, scientists can gain valuable insights into the levels and impacts of pollution in a given area.

They can indicate the presence of heavy metals in the air

Lichens are highly sensitive to the presence of heavy metals in the air, which can accumulate in their tissues and cause multiple physiological changes. Lichens do not have roots or a protective surface, so they absorb anything present in the air, including pollutants. This makes them excellent bioindicators of air quality.

Lichens can indicate the presence of heavy metals in the air through physiological variables, such as chlorophyll damage, lipid oxidation, and protein content. For example, arsenic has been found to impact chlorophyll degradation and protein content, while copper is associated with increased lipid oxidation. Lichens can also physically trap heavy metal particles in the intercellular spaces of their medulla, allowing for the retention of significant quantities of these metals.

The presence or absence of certain lichen species in an area can indicate the overall health of an ecosystem, and changes in lichen populations can serve as an early warning sign of environmental problems. For instance, the presence of Usnea lichens, also called old man's beard, indicates that coal has not been burnt in the area for a long time, as they do not grow in areas with sulphur dioxide pollution.

Lichen biomonitoring involves measuring the concentrations of pollutants in lichen tissue to assess the levels of pollution in the surrounding environment. Lichens are particularly useful for this purpose due to their ability to tolerate a wide range of environmental conditions and their prevalence in various ecosystems.

They are used in biomonitoring to assess air quality

Lichens are used in biomonitoring to assess air quality. They are highly sensitive to various pollutants, including heavy metals, and their health and distribution can be used to monitor air quality. Lichens absorb pollutants from the air and can accumulate them, which can become toxic. This makes them good indicators of the effects of air pollution on ecosystems.

Lichen biomonitoring involves measuring the concentrations of pollutants in lichen tissue and using that data to assess the levels of pollution in the surrounding environment. Lichens are also used to study the health of ecosystems, as their presence or absence can indicate the overall health of an ecosystem, and changes in lichen populations can signal environmental problems.

For example, the presence of Usnea lichens, also called old man's beard, indicates that coal has not been burnt in the area for a long time, as they do not grow in areas with sulphur dioxide pollution. Similarly, the presence of oakmoss lichen indicates clean air, as it is sensitive to nitrogen pollution.

Lichens are also used to monitor the impact of human activities on the environment, such as the use of fertilizers and other agricultural chemicals, and to develop strategies for reducing pollution.

Lichens are bioindicators of environmental pollution

Lichens are composite organisms that combine fungi, algae, and/or cyanobacteria. They are generally subtle and unnoticed, found on the ground, tree trunks, or rocks. Lichens are hearty organisms that can survive in extreme temperatures, water scarcity, and low nutrient levels. However, they are remarkably sensitive to air pollution. Their sensitivity to air pollution makes them excellent bioindicators of environmental pollution.

Lichens are used in biomonitoring, which involves monitoring environmental pollution using living organisms. They are good indicators of air pollution because they absorb nutrients from the air, and due to the lack of roots or a protective surface, they cannot filter what they absorb. This means that pollutants are taken straight inside the lichen, which can quickly become toxic. Lichens are also good bioindicators because they are easier to study than other indicators, such as butterflies, nematodes, frogs, and toads, and they respond more quickly to environmental changes.

Lichens can indicate the presence of specific pollutants, such as sulphur dioxide and nitrogen. Sulphur dioxide pollution comes from coal burning and industry, while nitrogen pollution comes from car engines, farms, and fertilizers. The presence or absence of certain lichen species can indicate the overall health of an ecosystem, and changes in lichen populations can be an early warning sign of environmental problems. For example, the presence of Usnea lichens, also called old man's beard, indicates that coal has not been burnt in the area for a long time.

Lichens are also important in the field of medicine, as they can be a source of potential antibiotics, antifungal, and anti-cancer drugs. Additionally, they play a crucial role in ecosystems by contributing to soil formation and nutrient cycling, and they are a food source for many animals, including reindeer, squirrels, snails, and insects.

They can be used to monitor the sustainability of ecosystems

Lichens are highly prevalent in around 8% of terrestrial ecosystems and are commonly found in environments with extreme temperatures, limited water availability, and low nutrient levels. Due to their ability to tolerate a wide range of environmental conditions, lichens are key components of many ecosystems and significantly contribute to the sustainability of natural systems.

Lichens play an essential role in ecosystems, including soil formation, habitat creation for plants and insects, acting as a food source, and nutrient cycling. Some species of lichen can fix nitrogen from the atmosphere, making it available to other plants in the ecosystem. Other species can absorb heavy metals from the soil, helping to detoxify polluted areas. This is another way in which lichens contribute to environmental sustainability.

Lichens are widely recognised as bioindicators of environmental pollution because of their sensitivity to various pollutants, including heavy metals. Therefore, their health and distribution can be used to monitor air quality. The presence or absence of certain lichen species can indicate the overall health of an ecosystem, and changes in lichen populations can be an early warning sign of environmental problems. By studying lichens, scientists can gain valuable insights into the health of ecosystems and take measures to ensure their sustainability.

Lichens are used in the field of biomonitoring, which involves monitoring environmental pollution using living organisms. Lichen biomonitoring involves measuring the concentrations of pollutants in lichen tissue and using that data to assess the levels of pollution in the surrounding environment.

Frequently asked questions