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BGYC63 Oct8

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Biological Sciences
Ivana Stehlik

Oct08 BIOC63 Threats to Biodiversityimpacts of global change on biodiversitythe effects of fast change on biodiversity Global Changemost peopel think of climate change when we hear global changethis is mostlikely to effect the Arctic areaNitrogen deposition is the least known however it is changing the most strongly in our types of ecosystems A Eutrophication N depositionwhy focus on thisN P K are typically most limiting nutrients important in fertilizers it is one of the most limiting resources for plantsand N has the largest human impactwhere is N locatedin the atmosphere N2 atmospheric composition78N2 21O2 004CO2 however this N2 in the atmosphere is very unreactiveso not very useful for living organisms3 types of reactive N 1 Organic from plant and animal tissue2 NH3 1 Nitrogen Cyclethe pool it comes from is from the atmospherethe lightening has enough heat and pressure turns atmospheric N into bioaccessbile Nanother more imporant was is N fixation by bacteria once the bacteria die they decompose in the soil and they turn into animo acids and they are decomposed by other bacteria into ammonia then nitrite then finally nitrateanother important bateria not free living but living on the roots of plants are rhzibia they use the nitrogen for themselves but the left over they transfers into plants which are then decomposed like the above or if the plants are consumed by animals through uric acid and urea turns into ammonia and so onthe nitrogen in the soil can also be be absorbed by other plantsand the access nitrate in soil will be absorved in the atmosphereN is so limited that any N abailable is taken by plants as soon as it was createdbefore we tinguered with N it pretty much stayed within the community as soon as something died it was quickly taken up by another living organism it was s closed systembefore we started using fossel fuel we had access through the activiety of bacterias 2 Human influence on the N cyclevery expensive reactionfueled by fossil fuels but through this we now have access to Nfrom this we have changed the global nirogen cyclebackground fixation rate is about 110Tg per yearby us we have more than doubled the numbers by the HaberBosch process the plants that we choose to plant and by burning fossil fuels
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