Soil zone A, living organisms, CO? production, biological activity, humus, microorganisms, decomposition, lime water test
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Abstract
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Abstract
The presence of living organisms in zone A of the soil is justified by the production of CO? due to biological activity, as shown by the lime water test.
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[...] Water is one of the main erosion agents: it can transport sediments through rivers and streams, carve valleys or gorges by carrying materials, or even cause coastal erosion through wave movement. Wind is also an important erosive agent, particularly in desert or semi-arid regions. It lifts fine sand particles and transports them over long distances, creating dunes or eroding rocks. Glaciers also play a role in erosion. As they move slowly, they tear off pieces of rock and transport enormous quantities of material, forming glacial valleys or moraines. [...]
[...] Then, under the effect of the accumulation of successive layers of sediments, the pressure increases and compresses these sediments, a process called compaction. Finally, the waters that circulate through the pores of the sediments transport dissolved minerals that precipitate and cement the particles together, solidifying the sedimentary layers into rock. This process is called cementation. Sedimentary rocks are therefore formed from these successive deposits of particles resulting from weathering and erosion. They can contain fossils or other indicators of past environmental conditions. [...]
[...] This process is caused by various factors, such as temperature fluctuations. For example, water that seeps into rock fissures freezes and expands in winter, causing fractures in the rock. This phenomenon is called gelivation. The crystallization of salts in arid environments can also fragment rocks: when water in the fissures evaporates, salts crystallize, exerting pressure on the rock. In addition, plant roots can infiltrate rock fissures, widening them until they break. In parallel, chemical weathering changes the chemical composition of rocks through chemical reactions. [...]
[...] Thus, weathering and erosion are natural processes that continually modify terrestrial landscapes. Weathering weakens rocks, while erosion transports fragments to other locations where they settle to form, in the long term, sedimentary rocks. This cycle illustrates well how geological phenomena interact to shape the surface of our planet. Example of a watershed (basin fed by erosion products). Exercise 2 Question 1 1. Vegetals 2. Litter 3. Horizon 1 4. Humus 5. Horizon 2 6. Roche mère calcaire. [...]
[...] This zone is therefore rich in organic matter. Observation from document 2 : I observe that lime water becomes turbid in the test carried out with a fresh soil sample taken from zone indicating the presence of carbon dioxide On the other hand, lime water does not become turbid with sterilized soil, which suggests that the absence of living organisms prevents the release of CO?. Knowledge : Now I know that the decomposition of organic matter produces carbon dioxide through biological processes. [...]
