chemical through its cycle ° The Carbon cycle Carbon-based organic molecules are essential to all organisms Photosynthetic organisms convert CO2 to organic molecules that are used by heterotrophs Reservoirs include fossil fuels, soils, and sediments, solutes in oceans, plants and animal biomass, the atmosphere and sedimentary rocks
CO2 taken up and released through photosynthesis and respiration o Volcanoes and burning fossil fuels contribute CO2 to atmosphere
Human modification of C Cycle o Fossil fuel burning Harvesting of unavailable resevoir o Conversion of forest to agriculture Wood stores carbon much longer than crops ° The Nitrogen Cycle Nitrogen exists mostly as N2 gas (triple bonded) o Most abundant element on planet o Makes up 78% of the atmosphere
Is breathed in but is inert Essential in living organisms o Muscles, proteins, amino acids o ATP, DNA, RNA Plants/living organisms organic waste detritivors capture Nitrogen and convert to ammonia which is available to plants again Nitrate produced from ammonia which can be used by plants but is also converted to N2 by denitrification by nitrifying bacteria o Nitrogen fixing bacteria to ammonia allowing plants to use nitrogen again Symbionts or free living bacteria Rhizobia fix nitrogen and live on plant roots Plant gets nitrogens and rhizobium get nutrients Rhizobia are specific to plant species Production of flavonoids that signal to the plant to create nodules that can house rhizobia
Nitrogen fertilizers help plants go better o Nitrogen is often limiting nutrient in terrestrial plants o
Nitrogen cycle and global warming 12/17/2015 ° Efficiency = percent assimilated put into new biomass Only assimilated materials is counted o Cellular respiration and growth Efficiency = growth / all assimilated material o Not feces ° Nitrogen cycle Agricultural techniques for nitrogen harvesting o Alfalfa can be grown and plowed to release nitrogen to soil Haber – Haber-Bosch reaction: factory to change N2 to ammonia o 400ºC and 200 atm can be done naturally done through lightning o Haber-Bosch reaction wins Haber nobel prize Invents mustard gas o Importance of Haber-Bosch reaction 75% of proteins in human diet comes from crops 50% of nitrogen in crop protein comes from synthetic fertilizer 37% of human protein is due to Haber- Bosch reaction Without Haber-Bosch, 2 billion less people Nitrate pollution o Nitrate pollution in water sources is caused by Synthetic fertilizer (54%)
Animal manure (33%) Irrigation water (8%) Other sources (5%) o Can cause loss of oxygen in water (eutrophication) Primary producer increases by a lot, increases primary consumer use of oxygen o Methemoglobinemia – blue baby syndrome Caused by drinking nitrate polluted water Five major human (Haber-bosch) impact on biosphere o Pollution o Acid rain o Ozone Depletion o Global warming/climate change o Reduced biodiversity °
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