Minerals

Several minerals are important to all living things can be found in abundance in the world ocean. Let us take a closer look at these minerals…

Manganese

Manganese nodules are composed of about 20-30% manganese, 10-20% iron oxide, 1.5% nickel, and less than 1% cobalt, copper, zinc, and lead. The manganese nodules can be very abundant, as on the ocean floor of the Pacific Ocean. But currently, there is no economical method of recovering the nodules from the deep sea.

Phosphorus

Phosphorus is required for growth by all organisms. Phosphorus is an essential nutrient for plants and animals in the form of ions PO43- and HPO42-. It is a part of DNA-molecules, molecules that store energy, and cell membranes.

Phosphorus can be found on earth in water, soil and sediments. In the atmosphere phosphorus can mainly be found as very small dust particles. Unlike the compounds of other matter cycles, phosphorus cannot be found in air in the gaseous state. This is because phosphorus is usually liquid at normal temperatures and pressures.

The phosphorus cycle is the slowest of the matter cycles. Phosphorus is most commonly found in rock formations and ocean sediments as phosphate salts. Phosphate salts that are released from rocks through weathering usually dissolve in soil water and are absorbed by plants. Animals absorb phosphates by eating plants or plant-eating animals. When these animals and plants die, the phosphates return to the soil or ocean during decay. From there, the phosphorus ends up in sediments or rock formations again, remaining there for millions of years. Eventually, phosphorus is released through weathering and the cycle starts over.

Organic wastes and remains accumulate in the sediment and as they decay, they release phosphorus compounds which form phosphate nodules. These nodules grow at the rate of about 1–10mm every1000 years.

Nitrogen

Nitrogen is found in the ocean in the living organisms that live there. But what makes nitrogen unique is the different “forms” in which nitrogen exists. The most common forms of nitrogen are the gases: N2, N2O, and NOx and organic nitrogen: N, NO3, and NH4.

The cycling of nitrogen is different from other cycling because of the different forms of nitrogen. Each organism plays an important part in how nitrogen cycles throughout the Earth.

  1. Bacteria and fungi covert organic nitrogen N to NH4+ in a process called “mineralization.”
  2. Bacteria also “nitrify” NH4+ to NO3- to producing NO and N2O.
  3. NO3- to N2, producing N2O in a process known as “denitrification” by bacteria.
  4. Finally, plants convert NO3- and NH4+ to organic nitrogen and the cycle continues.

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 Silicon

The cycle of silicon cycle differs from other cycles in that silicon does not have a gaseous phase. Furthermore, the solubility of silicon compounds in water is limited so most silicon is found in sedimentary or particulate form. Geochemical reactions are the main processes responsible for the formation of silicate rocks and their dissolution. Once in solution, however, silicon is cycled by biological activity.

In the oceans, diatom uptake maintains low concentrations of silicate in surface waters as a result of the production of biogenic silica (opal). The availability of dissolved silica varies geographically with high concentrations in upwelling regions of the oceans. After death, the siliceous cell walls of the diatom sink towards the seafloor.