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Like inorganic carbon, there are two main forms of organic carbon found in the ocean (dissolved and particulate). Dissolved organic carbon (DOC) is defined operationally as any organic molecule that can pass through a 0.2 μm filter. DOC can be converted into particulate organic carbon through heterotrophy and it can also be converted back to ...
The balance of these carbonate species (which ultimately affects the solubility of carbon dioxide), is dependent on factors such as pH, as shown in a Bjerrum plot.In seawater this is regulated by the charge balance of a number of positive (e.g. Na +, K +, Mg 2+, Ca 2+) and negative (e.g. CO 3 2− itself, Cl −, SO 4 2−, Br −) ions.
This rusting led to the deposition of the oxidized ferric iron oxide on the ocean floor, forming banded iron formations. Thus, the oceans rusted and turned red. Oxygen only began to persist in the atmosphere in small quantities about 50 million years before the start of the Great Oxygenation Event. [6]
Dissolved salt does not evaporate back into the atmosphere like water, but it does form sea salt aerosols in sea spray. Many physical processes over ocean surface generate sea salt aerosols. One common cause is the bursting of air bubbles , which are entrained by the wind stress during the whitecap formation.
Dissolved oxygen is a requirement for aerobic respiration, and while the surface ocean is usually oxygen-rich due to atmospheric gas exchange and photosynthesis, the mesopelagic zone is not in direct contact with the atmosphere, due to stratification at the base of the surface mixed layer.
In the ocean by volume, the most abundant gases dissolved in seawater are carbon dioxide (including bicarbonate and carbonate ions, 14 mL/L on average), nitrogen (9 mL/L), and oxygen (5 mL/L) at equilibrium at 24 °C (75 °F) [122] [123] [124] All gases are more soluble – more easily dissolved – in colder water than in warmer water. For ...
Each year, the ocean and atmosphere exchange large amounts of carbon. A major controlling factor in oceanic-atmospheric carbon exchange is thermohaline circulation. In regions of ocean upwelling, carbon-rich water from the deep ocean comes to the surface and releases carbon into the atmosphere as carbon dioxide.
Open ocean areas with no oxygen have grown more than 1.7 million square miles in the last 50 years, and coastal waters have seen a tenfold increase in low-oxygen areas in the same time. [47] Measurement of dissolved oxygen in coastal and open ocean waters for the past 50 years has revealed a marked decline in oxygen content.