Question

1. describe the biological origin of the following geological deposits

(a) coal:
(b) oil:
(c) limestone:
(d) peat:

1. using examples, compare and contrast the amount of time carbon spends in its various reservoirs.
2. explain the role of living organisms in the carbon cycle.
3. accumulated reserves of carbon such as peat, coal and oil represent a sink or natural diversion from the cycle. in natural circumstances, the carbon in these sinks eventually returns to the cycle through geological processes which return deposits to the surface for oxidation. explain the effect of human activity on the amount of carbon stored in sinks.

Explanation:

Step1: Describe coal's origin

Coal is formed from the remains of plant material buried in swamps, which is then compacted to form a hard - black material.

Step2: Describe oil's origin

Oil formed in the past when dead algae and zooplankton settled to the bottom of shallow seas and lakes, were buried and compressed under non - porous sediment.

Step3: Describe limestone's origin

Limestone is a sedimentary rock composed mostly of calcium carbonate, formed when the shells of mollusks and other marine organisms with calcium carbonate skeletons become fossilized.

Step4: Describe peat's origin

Peat forms when plant material is not fully decomposed due to acidic or anaerobic conditions.

Step5: Compare carbon residence time

In living organisms like trees, carbon residence time can be decades to centuries. In coal, oil and peat, carbon can be stored for millions of years. In the atmosphere, carbon (as carbon dioxide) has a residence time of about 3 - 4 years on average.

Step6: Explain organisms' role in carbon cycle

Living organisms play a crucial role in the carbon cycle. Plants take in carbon dioxide during photosynthesis and store carbon in their biomass. Animals consume plants and release carbon dioxide during respiration. Decomposers break down dead organic matter and release carbon back into the environment.

Step7: Explain human impact on carbon sinks

Human activities such as extraction and burning of fossil fuels (coal, oil) and draining of peatlands release large amounts of carbon that was stored in these sinks into the atmosphere, increasing the amount of atmospheric carbon dioxide and disrupting the natural carbon cycle.

Answer:

(a) Coal is formed from the remains of plant material buried in swamps and subsequently compacted.
(b) Oil formed from dead algae and zooplankton that settled to the bottom of shallow seas and lakes, were buried and compressed under non - porous sediment.
(c) Limestone is formed from the fossilization of the shells of mollusks and other marine organisms with calcium carbonate skeletons.
(d) Peat forms when plant material is not fully decomposed due to acidic or anaerobic conditions.

1. Carbon can be in living organisms (e.g., trees) for decades - centuries, in fossil fuels (coal, oil, peat) for millions of years, and in the atmosphere for about 3 - 4 years on average.
2. Plants take in carbon dioxide during photosynthesis, animals release it during respiration, and decomposers break down dead matter to release carbon.
3. Human activities like burning fossil fuels and draining peatlands release stored carbon into the atmosphere, disrupting the carbon cycle.