Question

The concentrations of dissolved CO₂ and nutrients such as nitrate (NO³⁻) and phosphate (PO₄³⁻) are generally lower in the surface ocean than they are in the deep ocean. This is because ______ moves these substances from the surface ocean to the deeper ocean via three processes:

1. Primary production consumes the CO₂ and nutrients in the euphotic zone to make organic matter.
2. Some of that organic matter sinks to deeper water.
3. Respiration of the sinking organic matter regenerates the CO₂ and nutrients in the deeper waters.

Answer 1

The concentrations of dissolved CO₂ and nutrients are lower in the surface ocean due to primary production, sinking of organic matter, and respiration in deeper waters, which collectively move these substances from the surface to the deep ocean.

Step-by-step explanation:

The concentrations of dissolved CO₂ and nutrients such as nitrate (NO³⁻) and phosphate (PO₄³⁻) are generally lower in the surface ocean than in the deep ocean. This pattern is a result of a process that moves these substances from the surface ocean to the deeper ocean through three main processes:

1. Primary production consumes the CO₂ and nutrients in the euphotic zone to produce organic matter through photosynthesis.
2. Some of the formed organic matter sinks to deeper water, carrying the nutrients with it.
3. Respiration of this sinking organic matter by decomposers regenerates CO₂ and nutrients in the deep waters, replenishing their levels.

Factors like ocean upwelling also contribute to the redistribution of nutrients. During upwelling, deep water rich in nutrients is brought to the surface, replenishing the nutrient levels in the upper layers of the ocean, allowing for continued primary production. However, this is temporary, and over time, sinking matter and respiration ensure that deep waters have higher concentrations of these substances.