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14 Cards in this Set
- Front
- Back
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gaseous cycle
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sources: atmosphere and oceans
-nitrogen, oxygen, CO2 |
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common structure of biological cycles
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input
internal cycling output |
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output (6 ways)
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-diffusion of gases
-immigration of heterotrophs -climatic events (flooding) -harvesting -fire -runoff |
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CO2 source
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fossil fuels
oceans -carbonate ions -dead organic matter -living matter (phytoplankton) Terrestrial biosphere -dead organic matter (soil carbon) -living matter Atmosphere **most is in deep ocean |
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human impact of carbon cycle
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rapid injection of CO2 into atmosphere from burning fossil fuels and forest clearing
-increased by more than 25% in the past 100 years |
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greenhouse gases
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-water vapor, CO2, ozone
* warms earths surface |
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GCMs (general circulation models)
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-increase in avg global temp and precip
-warming greatest in winter months in the northern lat -increasing variability of climate |
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nitrogen
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-important for protein building
-N2 composes 99% of atmosphere -N is unavailable to most of life -nitrogen cycle is driven by microbes |
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fixation
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conversion of N2 to ammonia and nitrate
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high energy fixation
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conversion to ammonia and nitrate by energy from cosmic radiation, meteorite trails, or lightning
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biological fixation
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possible bc of bacteria
-legumes -cyanobacteria -some lichens |
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mineralization
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bacteria and fungi decompose plant and animal proteins to amino acids which are oxidized to CO2, H2O, and ammonia
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nitrification
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Nitrosomonas- convert ammonia to nitrite
nitrobacter oxidize nitrite to nitrate *nitrates are absorbed by plants |
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denitrification
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nitrate is reduced and returned to the atmosphere
-requires anaerobic conditions |
