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Nitrogen & Phosphorous Group #3: Neil Mehta Misha Nelson Tristan Jenkins Jenna Colhouer Brendon Esperancilla Nitrogen • Chemical Reactions • Inorganic and organic reservoirs for the element • Pathway of movement • Impact of human intervention on the cycle Chemical Reactions • Nitrogen: (N2) most abundant element in atmosphere (78% of troposphere volume) • Combines with atmospheric oxygen to form nitrogen dioxide gas (NO2) • (N2) cannot be metabolized as a nutrient – Electrical discharges cause N2 & O2 to react – Certain bacteria (Rhizobium, etc.) can fix nitrogen for use by plants Inorganic and organic reservoirs for the element • Inorganic: – Atmospheric gas • Organic: – Plants are consumed by animals as a source of nitrogen – Detritus resulting from decomposition of formerly living organisms Pathway of movement • Nitrification: ammonia converts to nitrite (NO2-) & nitrate (NO3-) • Assimilation: plant roots absorb inorganic ammonia, ammonium ions, and nitrate ions – Used for synthesis of DNA, proteins, etc. • Ammonification: bacteria decompose dead matter into constituent components, including ammonia and ammonium salts • Denitrification: bacteria convert ammonia and ammonium back into nitrite and nitrate, then becoming N2 and nitrogen oxide Impact of human intervention on the cycle • When we burn any fuel, it adds large amounts of nitric oxide • Acid rain: formed by HNO3 (nitric acid=atmospheric water and nitrogen dioxide) and dissolves in rain or snow • Farm animals release methane into atmosphere Phosphorous • Chemical Reactions • Inorganic and organic reservoirs for the element • Pathway of movement • Impact of human intervention on the cycle Chemical Reactions • Very little P circulates in atmosphere – At Earth STP, P is not usually gaseous and mostly mineral • • • • • • P is typically found in terrestrial rock and ocean sediment Helps form structure of bones in animal skeletons Often used in fertilizer Composes ATP for nearly all cellular activities Composes phospholipid bilayer of cell membranes Most abundant form: orthophosphate (PO43-) Inorganic and organic reservoirs for the element • Inorganic: – Mineral formations – Ocean sediment • Organic: – Aquatic and terrestrial plants – Bones of terrestrial animal Pathway of movement • • • • • • • • Starts in mineral form Weathering deposits it in soils Plants absorb from soil Animals consume plants and their phosphorous Reintegrated into soil after death of animal Can run off into ocean Ocean plants ocean animals Some settles into marine sediment – Mined by humans for fertilizer Impact of human intervention on the cycle • We harvest phosphorous from sediment to make fertilizer • Remove trees from tropical forests – No plants, no absorption from soil • No plant roots, no soil to begin with! • Pollute aquatic environments – Overabundance of P promotes algal bloom, which helps bacteria thrive; bacteria consume too much oxygen, and fish drown!? HEY!