Which of the following are ways that carbon can move from the atmosphere to the hydrosphere?

• A. Dissolution of atmospheric CO\(_2\) into ocean water and uptake by aquatic photosynthetic organisms
• B. Release of CO\(_2\) from ocean water to the atmosphere
• C. Decomposition of marine organisms releasing CO\(_2\) into the atmosphere
• D. Volcanic eruptions emitting CO\(_2\) directly into the atmosphere

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the carbon cycle and its components. The carbon cycle describes how carbon moves through the atmosphere, hydrosphere, biosphere, and geosphere. Focus on the interactions between the atmosphere and hydrosphere in this problem.
2. Step 2: Recognize that carbon dioxide (CO\(_2\)) can dissolve into ocean water. This process is called dissolution, where atmospheric CO\(_2\) reacts with water to form carbonic acid (H\(_2\)CO\(_3\)), which can further dissociate into bicarbonate (HCO\(_3^-\)) and carbonate ions (CO\(_3^{2-}\)).
3. Step 3: Identify the role of aquatic photosynthetic organisms. These organisms, such as phytoplankton, take up dissolved CO\(_2\) during photosynthesis to produce organic compounds, effectively transferring carbon from the hydrosphere to the biosphere.
4. Step 4: Eliminate options that describe processes moving carbon in the opposite direction (e.g., from the hydrosphere to the atmosphere). For example, the release of CO\(_2\) from ocean water to the atmosphere occurs during outgassing, not dissolution.
5. Step 5: Exclude processes unrelated to the atmosphere-hydrosphere interaction, such as volcanic eruptions or decomposition of marine organisms, as these primarily involve the geosphere or biosphere rather than the hydrosphere.