Biological weathering

biological weathering

1. BIOLOGICAL WEATHERING EZHILMATHI. S 2015006015

2. DEFINITION Biological weathering  is the weakening and subsequent disintegration of rock by plants, animals and  microbes

3. BIOLOGICAL WEATHERING Organic weathering It is the disintegration of rocks as a result of the action by living organisms Plant and animals have a significant effect on the rocks as they penetrate or burrow into the soil

4. ASSOCIATION Biological weathering can work with physical weathering, for example root exert pressure which helps to weakening rocks It can also produce chemical weathering, for example where microorganisms produce organic acids which help to dissolve minerals Microscopic organisms can produce organic chemicals that can contribute to the rock’s mineral weathering

5. GROWING PLANT ROOTS The roots penetrate into the soil in search of nutrients and water They go through cracks or joints in the rocks and as they grow they progressively crack the rock apart They also emit organic acids that aid to dissolve the rock’s minerals Although the process is physical, the pressure is exerted by a biological process

6. MICROBIAL ACTIVITY Algae, moss, lichens and bacteria   break down rock minerals by altering the rock’s chemical composition Lichen is fungi and algae living together in a symbiotic relationship Fungi release chemicals that break down rock minerals; the minerals thus released from rock consumed by algae

7. MICROBIAL ACTIVITY These compounds can break down iron and aluminum minerals in the rocks They release acidifying molecules and chelating compounds The amount of biological activity that breaks down minerals depends on how much life is in that area They arise out of bio-chemical reactions They also bring about moist chemical micro-environments

8. BURROWING ANIMALS This   can move rock fragments to the surface Moles, squirrels and rabbits can speed up the development of fissures Piddock shells drill into rocks for protection by releasing acids to dissolve the rocks There are many small animals that eat away the rock’s minerals and bore hole so as live inside it

9. HUMAN ACTIVITIES This equally dig, crash, and widen the cracks and wind up fragmenting the rocks apart These activities include mining, road construction, and housing developments

10. RESEARCHES Historically, scientists have studied weathering as an abiotic process. In the mid 1980’s, scientists studying geothermal sediments from Yellowstone  found the some of the first evidence of biological weathering when they discovered iron-silicate minerals in association with bacterial remains. The first application that included biological weathering in LAPSUS was Temme and Veldkamp’s study in South Africa. The original implementation of biological weathering was developed by Minasny and McBratney , 2006 .

11. RECENTS Biological weathering and the long-term carbon cycle: integrating mycorrhizal evolution and function into the current paradigm Crystalline nanotube -forming bacteria help crumble mountains in a tropical rainforest

12. REFERENCES http :// www.eartheclipse.com Das, Dilip kumar / 1996/ introductory soil science http://www.thelonelyspore.com

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