Oxygen releases oxygen into the atmosphere, while respiration, decay, and combustion remove it from the atmosphere. In the present equilibrium, production and consumption occur at the same rate. Free oxygen also occurs in solution in the world's water bodies. The increased solubility of at lower temperatures (see Physical properties) has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content. Water polluted with plant nutrients such as nitrates or phosphates may stimulate growth of algae by a process called eutrophication and the decay of these organisms and other biomaterials may
Cultural eutrophication Nova Scotia. In order to match an increase in food demand, agricultural production relies heavily on the use of fertilizers to increase overall crop productivity. These fertilizers contain high amounts of phosphorus and nitrogen, which results in excess amounts of nutrients entering the soil. The nutrients that are not absorbed by the plant leach out of the soil and enter freshwater systems, such as rivers. These nutrients can eventually end up in aquatic ecosystems, and are a contributor to increased eutrophication. Cultural eutrophication Cultural eutrophication is the process that speeds up natural eutrophication because of human activity. Due to clearing