Question

what occurs below the calcium carbonate compensation depth? calcium carbonate begins to precipitate into a solid. the rate of calcareous sediment accumulation is greater than the rate of dissolution. calcium carbonate begins to dissolve. calcareous oozes start to form. seawater becomes less acidic.

Explanation:

The calcium carbonate compensation depth (CCD) is the depth in the ocean where the rate of calcium carbonate (CaCO₃) dissolution equals the rate of supply. Below the CCD, the pressure and acidity conditions cause calcium carbonate to dissolve faster than it accumulates. Let's analyze each option:

• "Calcium carbonate begins to precipitate into a solid": Precipitation (formation of solid CaCO₃) is more likely above the CCD where conditions favor accumulation, not below. Eliminate this.
• "The rate of calcareous sediment accumulation is greater than the rate of dissolution": Above the CCD, accumulation rate > dissolution rate. Below CCD, dissolution rate > accumulation rate. Eliminate this.
• "Calcium carbonate begins to dissolve": Below the CCD, the environment (higher pressure, more acidic) makes CaCO₃ start to dissolve because dissolution rate exceeds accumulation. This matches.
• "Calcareous oozes start to form": Calcareous oozes form above the CCD where CaCO₃ accumulates. Below CCD, they don't form as CaCO₃ dissolves. Eliminate this.
• "Seawater becomes less acidic": As depth increases, seawater becomes more acidic (due to more CO₂ dissolution), not less. Eliminate this.

Answer:

Calcium carbonate begins to dissolve.