Atmospheric input is negligible in

Options

A. Carbon cycle
B. Phosphorus cycle
C. Oxygen cycle
D. Nitrogen cycle

Answer

To solve the question "Atmospheric input is negligible in," we need to analyze the given options and understand the characteristics of different biogeochemical cycles. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Concept of Biogeochemical Cycles
Biogeochemical cycles are pathways through which essential elements of living matter are circulated in the ecosystem. These cycles can be classified into gaseous and sedimentary cycles.

**Hint:** Identify the difference between gaseous and sedimentary cycles.

### Step 2: Analyze Each Cycle
- **Carbon Cycle:** Carbon dioxide (CO2) from the atmosphere is a significant input in the carbon cycle. Therefore, atmospheric input is present here.

**Hint:** Look for the role of gases in the carbon cycle.

- **Oxygen Cycle:** The oxygen cycle involves atmospheric oxygen (O2) and water vapor, which contains oxygen. Thus, atmospheric input is also significant in this cycle.

**Hint:** Consider how oxygen is sourced in the ecosystem.

- **Nitrogen Cycle:** The nitrogen cycle includes atmospheric nitrogen (N2) as a key component, indicating that atmospheric input is present here as well.

**Hint:** Think about how nitrogen enters the ecosystem.

- **Phosphorus Cycle:** The phosphorus cycle is primarily a sedimentary cycle. Phosphorus does not exist in a gaseous state in the atmosphere; it mainly cycles through soil and water. Thus, there is negligible atmospheric input in the phosphorus cycle.

**Hint:** Remember that phosphorus is primarily sourced from rocks and sediments.

### Step 3: Conclusion
Based on the analysis, the cycle in which atmospheric input is negligible is the **phosphorus cycle**. This is because phosphorus does not enter the cycle from the atmosphere but rather from the lithosphere.

### Final Answer
The answer is **phosphorus cycle**.

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