NITROGEN CYCLE Nitro gen Cycle Composes about fourfifths

NITROGEN CYCLE

Nitro gen Cycle • Composes about four-fifths (78. 03 percent) by volume of the atmosphere • an essential part of the amino acids. It is a basic element of life. • is an important element in plant nutrition • in the form of protein is an important constituent of animal tissue.

Nitrogen Cycle • natural cyclic process in the course of which atmospheric nitrogen enters the soil and becomes part of living organisms

Nitrogen Cycle

Amounts of Nitrogen Reservoir Metric tons nitrogen Atmosphere 3. 9*1015 Land organic matter Biota 1. 1*1011 2. 5*1010 Ocean soluble salts Biomass 6. 9*1011 5. 2*108

Forms of Nitrogen in Ocean Formula Function Pathway Habitat Nitrate NO 3 _ Electron acceptor, nitrogen source Nitrogen assimilation, dissimilatory nitrate reduction and denitrification Coastal upwelling zones, deep ocean Ammonium NH 4+ Electron donor, energy source, nitrogen source Nitrogen assimilation, ammonia oxidation (aerobic), and anaerobic ammonia oxidation Important, rapidly recycled pool in open ocean, intermediate in decomposition of organic matter Electron donor and acceptor, energy source, nitrogen source Nitrification (nitrite oxidation), denitrification Found at margins of oxic/anoxic regions, intermediate in oxidation and reduction pathways _______ High concentration in equilibrium with atmosphere, available to N 2 -fixing microorganisms Nitrite - NO 2 Dinitrogen N 2 Nitrogen source Nitrous oxide N 2 O Trace gas, electron acceptor, electron donor End or by-product of nitrification and denitrification Intermediate in reductive pathway, also formed in nitrification and at oxic/anoxic interfaces and anoxic or suboxic zones Urea CH 4 N 2 O Nitrogen source Nitrogen assimilation Decomposition product, potentially important nitrogen source in water column

Steps of Nitrogen Cycle • • • Nitrogen Fixation Nitrogen Assimilation Ammonification Nitrification Denitrification

Nitrogen Fixation • Nitrogen gas is converted into inorganic nitrogen compounds. It is mostly (90 percent) accomplished by free-living, nitrogen-fixing bacteria.

Nitrogen-Fixing Bacteria • symbiotic bacteria living on the roots of plants (mostly legumes and alders) • cyanobacteria (formerly known as bluegreen algae) • archaebacteria (also known as archaea) in deep-sea hydrothermal vents

Nitrogen Fixation by Lightning • The high energies provided by lightning and cosmic radiation serve to combine atmospheric nitrogen and oxygen into nitrates, which are carried to the Earth’s surface in precipitation.

Steps of Nitrogen Cycle • • • Nitrogen Fixation Nitrogen Assimilation Ammonification Nitrification Denitrification

Nitrogen Assimilation • are assimilation of nitrates and ammonia resulting from nitrogen fixation into the specific tissue compounds of algae and higher plants. Animals then ingest these algae and plants, converting them into their own body compounds.

Steps of Nitrogen Cycle • • • Nitrogen Fixation Nitrogen Assimilation Ammonification Nitrification Denitrification

Ammonification • The remains of all living things—and their waste products—are decomposed by microorganisms which yields ammonia.

Steps of Nitrogen Cycle • • • Nitrogen Fixation Nitrogen Assimilation Ammonification Nitrification Denitrification

Nitrification • a process carried out by nitrifying bacteria, transforms soil ammonia into nitrates, which plants can incorporate into their own tissues. 1 rst step catalyzed by Nitrosomonas 2 NH 4+ + 3 O 2 2 NO 2 - +2 H 2 O+ 4 H+ 2 nd step catalyzed by Nitrobacter 2 NO 2 - + O 2 2 NO 3 -

Steps of Nitrogen Cycle • • • Nitrogen Fixation Nitrogen Assimilation Ammonification Nitrification Denitrification

Denitrification • The process where nitrates are metabolized by denitrifying bacteria to free nitrogen and returned to the atmosphere

Nitrogen Cycle in Ocean • In groups construct a poster or drawing diagram about how the Nitrogen Cycle would work in the ocean • Label steps (Nitrogen Fixation, Nitrogen Assimilation, Ammonification, Nitrification, Denitrification)

Nitrogen Cycle In Ocean

Nitrogen Cycle in Fish Tanks