Oxygen enters the water most readily from?

Oxygen enters the water most readily from aquatic plants due to the process of photosynthesis. During photosynthesis, aquatic plants absorb carbon dioxide and sunlight to produce energy, releasing oxygen as a byproduct. This oxygen is then diffused into the water, contributing significantly to the overall oxygen levels in aquatic ecosystems.

While other sources like air do contribute oxygen to water bodies through gas exchange at the water surface, the direct production of oxygen from photosynthetic organisms, such as aquatic plants, has a more substantial and sustained effect, especially in environments where these plants are abundant. Aquatic plants also offer shelter and habitat for various aquatic organisms, which further enhances the ecosystem's health and oxygen dynamics.

Soils and springs can also influence oxygen levels but do so in more indirect ways, or at much lower rates compared to the direct release from aquatic plants.