Oceanography

Nutrients in Sea water

Near surface nutrient concentration in seawater is as follows

Nutrient	Concentration (ppm)
Phosphorus (P)	0.07
Nitrogen(N)	0.5
Silicon(Si)	3

Nutrients are essential for plant growth. All plants, including those that live in the ocean, convert nutrients into food(organic compounds such as sugar) by photosynthesis. Nutrients in seawater are compounds that consist primarily of nitrogen (N), Phosphorous (P), and silicon (Si). Representative concentrations of these nutrients in the ocean are listed in the above Table 1.   The concentrations are specified in parts per million (ppm). Most plants cannot use elemental nitrogen and phosphorus and satisfy their nutrient needs by absorbing phosphate (PO^3-₄) and nitrate (NO₃^-). Silicon is used by important groups of microscopic plants (diatoms) and animals (radiolarian 8).Because of biological uptake and release, the concentrations of nutrients in seawater, as on land, vary from place to place and over time at any one place. Hence,Oceanographers refer to these substances as non-conservative ions of seawater, signifying that levels of these substances are not constant in water, but vary over time and from place to place. Limiting nutrient is a missing nutriend among three nutrients needed. For seawater it is nitrogen and for freshwater it is phosphorous.