71% of earth surface is covered with ocean.Just like all the water bodies mainly ocean provide water for the evaporation process. 78% of global precipitation occurs over the ocean. The precipitated water in the land also runoff to the ocean through freshwater bodies. The height of the ocean surface is affected by the precipitation indirectly. 

Nitrogen is absorbed by the ocean from the atmosphere. Dissolved nitrogen in the sea water fixed by micro organisms to form nitrogen compound which is useful to marine life. Nitrogen gas (N₂ ) , a form of Nitrogen is the most abundant form of nitrogen in ocean. Nitrogen is taken by bacteria in the ocean then covert into ammonium through the process of Nitrogen fixation. Ammonium converts into nitrite and then to nitrite to nitrate by the process of nitrification. Micro organisms in the ocean consume ammonium, nitrate and nitrite.

Carbon is the 4^th most abundant element in the Earth. The biggest carbon pool in the earth is ocean. So the ocean plays a major role in carbon cycle. Carbon dioxide can be taken by oceanic photosynthetic organisms like phytoplankton . The food produced by those organisms taken by marine organisms. After marine organisms die their bodies deposited in the depth of the ocean. Some amount of the carbon in that dead bodies is settle their for hundreds of years and gradually turning into coal or oil deposits. It can be also dissolved in the ocean forming carbonic acid. Carbon is rapidly exchanged between the ocean and the atmosphere to maintain the equilibrium of the earth. 

Phosphorus enters to the ocean by leaching or runoff. They dissolved in the ocean and contributed to marine food web. Phosphorous helps to boost the growth of phytoplankton which is the primary level of food chain. The phosphorous containing compounds from the bodies of marine organisms or from wastes deposited in the ocean floor and they form new sedimentary rocks. These rocks may be moves to land from the ocean over a long period of time by the process of geological uplift.

Silicon is the 2^nd most abundant element on the earth. Large amount of silicon can be found in the ocean. The residence time of silicon in the ocean is over 400 years relative to the total biological uptake in surface waters. Carbon dioxide uptake rate in the ocean is directly proportional to the rate of silicate weathering which is caused by high uplift rates. This process controls the p_H level of ocean.

 

CRM-2021-005

Group 03

 

• Evaporation of ocean water and formation of sea ice further increase the salinity of the ocean. However these processes which increase salinity are continually counterbalanced by processes that decrease salinity, such as the continuous input of fresh water from rivers, precipitation of rain and snow, and the melting of ice.

Nitrogen Cycle

Nitrogen cycle and ocean- In the open ocean, as on land, fixed nitrogen is one of the most important growth-limiting nutrients for photosynthetic organisms (primary producers) such as algae and marine bacteria. Nitrogen can also serve as an energy source or as an oxidant for marine bacteria and archaea. (Archaea are single celled organisms that look similar to bacteria, but which are in an entirely separate biological domain).

The ocean absorbs nitrogen gas from the atmosphere. In open-ocean areas with low concentrations of nutrients (“oligotrophic” regions), some of this nitrogen is taken up by microbes and transformed into various chemical compounds. The key steps in this process are listed below and shown in the simplified diagram at right (click on it to see a larger version).

Nitrogen gas (N2) from the atmosphere dissolves into seawater at the ocean surface. Nitrogen gas is the most abundant form of nitrogen in the ocean, but is not useful to most living things.