Final answer:
The statement that oxidation in rocks is often initiated by dissolved oxygen in water is true. Oxygen plays a crucial role in the corrosion and weathering of materials, as well as in maintaining healthy aquatic ecosystems by supporting life and aiding in pollutant oxidation.
Step-by-step explanation:
Oxidation in rocks is indeed often initiated by dissolved oxygen in water. This is a true statement, reflected in the fact that oxygen is an essential reactant in the oxidation reactions that contribute to the weathering and corrosion of rocks. When dissolved in water, oxygen can facilitate the formation of rust on iron, as seen in the chemical reaction: 4 FeO + O₂ → 2 Fe₂O₃. This oxidation process is not only limited to iron but occurs with various materials and can sometimes lead to the formation of protective layers on metals like aluminum and copper.
Moreover, the presence of dissolved oxygen is critical for maintaining the health of aquatic ecosystems by supporting life and aiding in the biological oxidation of pollutants. In historical contexts, shifts in dissolved oxygen concentrations have been evidenced by the geological record, such as in the banded iron formations that reveal the atmospheric conditions of early Earth.