EOSC 112 Lecture Notes - Lecture 7: Anoxic Waters, Ocean Gyre, Redfield Ratio

• School: UBC
• Department: Earth and Ocean Sciences
• Course: EOSC 112
• Professor: Debeare Bart

Document Summary

The nitrogen cycle is more complex than the p cycle as nitrogen (n) is found in many different oxidation states ranging from -3 in ammonia and amino acids to the most oxidized at +5 in nitrate. N2 (0 oxidization) is the most abundant of the atmospheric gases at 78%. Note: all major transformations involving nitrogen are mediated by the biota. In the ocean, n-fixation is mostly done by the blue-green algae/cyanobacteria (photoautotrophs). As a result of the catalyzing effect that nitrate is found at high concentration in the deep sea. Important note: nitrogen fixation is inhibited in seawater. Since it takes a lot of energy to (cid:271)reak the (cid:271)o(cid:374)ds (cid:271)et(cid:449)ee(cid:374) the n, it"s easier for phytopla(cid:374)kto(cid:374) to use (cid:374)itrate or ammonia. N fixers grow slowly if there is a lot of seawater, the phytoplankton grows faster and out-competes the n fixers for phosphate which they need.