Dissolved O2 concentration is high near the ocean surface due to..Group of answer choicesbacteriadownwellingrespirationphotosynthesisdecay

The dissolved O2 concentration is high near the ocean surface due to photosynthesis. Here's why:

1. Photosynthesis: This is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigments. During photosynthesis, plants absorb carbon dioxide and sunlight to produce glucose and oxygen. The oxygen is released into the water, increasing the concentration of dissolved O2.

2. Location: Photosynthesis occurs near the surface of the ocean because sunlight can only penetrate the water to a certain depth. The upper layer of the ocean where sunlight can penetrate is called the euphotic zone. This is where photosynthesizing organisms, like phytoplankton, live.

3. Oxygen Production: As these organisms photosynthesize, they release oxygen into the water. This increases the concentration of dissolved O2 near the surface of the ocean.

So, while bacteria, downwelling, respiration, and decay can all affect levels of dissolved O2 in the ocean, it is photosynthesis that is primarily responsible for high concentrations near the surface.