Biological weathering is the removal of minerals from the environment as a result of organism growth or movement. Biological weathering, like other types of weathering, can contribute to further degradation of rocks and rock particles by making them more vulnerable to other environmental factors, biotic or abiotic. Both mechanical and chemical weathering are aided by living organisms. Lichens and mosses thrive on bare rock surfaces, creating a more humid chemical microenvironment. This article will explain to you about Biological Weathering - Denudational Processes which will be helpful in Geography preparation for the UPSC Civil service exam.

What is Biological Weathering?

• Biological weathering is the removal of minerals and ions from the environment due to the development or movement of organisms.
• It is also known as Organic Weathering. Its main agents are animals, microorganisms, plants, and humans.
• Organisms such as earthworms, termites, rodents, algae, dead plants, and animals aid in the fertilization of soil, which is beneficial for agriculture and irrigation.
• In fact, by ploughing and cultivating, humans are mixing and bringing air, water, and soil minerals present on the earth's surface into contact.
• These organisms, on the other hand, produce chemicals that absorb all of the nutrients from the rock and aid in the breakdown of the rock on which they live. Biological weathering is widespread and visible everywhere.
• Bacteria, algae, and lichens produce chemicals that aid in the breakdown of the rock on which they live, allowing them to obtain the nutrients they require. They generate weak acids, which convert some minerals to clay.
• Agents of biological weathering are:
  • Animals
  • Microorganisms
  • Plants
  • Humans

Types of Biological Weathering

• Plant Roots: Some trees grow within rocks, which contributes to biological weathering. Plant and tree roots penetrate the soil in search of nutrients and water.
  • As the roots penetrate the soil, they pass through cracks or joints in the rocks, gradually cracking the rock apart.
  • Larger growing roots can also put pressure on nearby rocks.
  • Some plant roots also produce organic acids that help dissolve the minerals in rocks.
• Microbial Activity: Organic acids are produced by microscopic organisms such as algae, moss, lichens, and bacteria.
  • This changes the chemical composition of the rock and gradually erodes its outer layer.
• Burrowing animals: Some animals, such as moles, squirrels, and rabbits, can create fissures in rocks. These animals, however, suck up the nutrients from the rock by creating a fissure. It gradually breaks the rock into large chunks.
• Human activities: Human activities include agricultural activities, mining, construction, and other man-made fragmentation of rocks and soil. These activities cause cracks in the rocks, which eventually break them.

Biological Weathering - Classification

Biological Weathering can be classified into physical means and chemical means.

Biological Weathering by Physical Means

By Plants

• Plants can grow almost anywhere there is water.
• Tree and plant roots can generally weather rocks biologically by growing into cracks and crevices in rocks and soil.
• As a result, they are more likely to break and eventually fall apart.

Biological Weathering by Plants

By Animals

• Shrews, moles, earthworms, and even ants are burrowing animals that contribute to biological weathering.
• These animals, in particular, excavate holes in the ground and transport rock fragments to the surface.
• As a result, these fragments are more vulnerable to other environmental factors that can exacerbate their weathering.
• The Piddock shell is a type of animal that can drill through rocks to protect itself.
• It can produce fractures in the rock and consume the minerals it contains by producing acids that can break it down and turn it into bits.

Biological Weathering by Shrews

By Humans

• Humans, like any other species, can contribute to biological weathering in an indirect way.
• The dirt particles are smashed into tiny pieces just by walking and running.
• Planting and road construction are examples of human activity that can contribute to biological weathering.

Weathering by Humans

Biological Weathering by Chemicals Means

By Plants

• Plant roots that grow deeper into the soil tend to develop cracks and crevices in marbles and limestones by creating acids that can damage them over time.
• Humus, an organic component of soil, can increase water availability, which increases the physical and chemical breakdown of rocks.
• Also when plants die, their roots (and other parts) decompose and are converted to organic matter, which emits carbon dioxide.
• When CO₂ reacts with water (H₂O), it produces weak carbonic acid, which can degrade the surfaces of rocks and rock particles.

Biological weathering through chemicals released by plants

By Microorganisms

• Microorganisms, despite their small size, can break down even the hardest rocks and soil.
• When a fungus releases chemicals that can break down minerals in rocks, the minerals are liberated.
• These minerals are consumed by algae, which further wear and form cracks and crevices in the rock.
• As a result, cracked rocks are more likely to disintegrate.
• Actinomycetes are a type of bacteria that have successfully degraded rocks in Egypt through acid production, mineral solubilization, and metal leaching.

Biological weathering through chemicals released by microorganisms

By Animals

• While ants and termites can aid in the physical breakdown of rocks, they can also aid in their biological degradation.
• These animals, in addition to creating holes and passages in the ground, allow for the easy passage of oxygen and water into the soil resulting in the dissolution of soil, rocks, and rock particles alike.
• When animals die, their bodies are converted into substances that, when combined with minerals found in soil and rocks, can contribute to the degradation of the environment.

Biological weathering through chemicals released by animals

Conclusion

Biological weathering occurs as a result of organisms' daily activities. Organic processes include biological rock dissolution caused by bacterial activity, humic acids, and bioerosion or destruction. It is caused by the addition or removal of ions and minerals from the weathering environment, as well as physical variations caused by organism movement or development. It is also the wear and tear on rock caused by plants, animals, and microbes.