Aluminum is insoluble in water. In addition, aluminum oxide and aluminum hydroxide, the predominate aluminum salts are considered insoluble in water. However, seawater contains between 0.013 and 5 parts per billion of aluminum.
Aluminum reacts with water to form aluminum oxide. This oxide forms a protective barrier over the object to prevent damage from water. Mineral forms of aluminum, such as bauxite, weather naturally, allowing more soluble salts of aluminum to enter surface waters. Runoff adds aluminum to the rivers and ultimately the ocean. Pollution from industrial processing also increases the amount of aluminum in the oceans. The Atlantic Ocean has a higher aluminum concentration than the Pacific.