ecology exam 4 Flashcards
percent of carbon dioxide in the atmosphere
0.0410%
industrial nitrogen cycle pathway
industrial N fixation in factories to plants utilizing from fertilizer to grow crops and fed to animals to us eating animal products to incorporating N to DNA
natural nitrogen cycle pathway
nitrogen gas in air to N-fixing by lightning to non-N-fixing producers or nitrogen fixing producers like legumes or cyanobacteria to heterotrophs
nitrogen gas back to air
from animals and n-fixing producers to ammonium compound in soil to nitrate compounds in soil bacterias through denitrification to n2 in the air
biological nitrogen fixation
conversion of N2 to ammonium and nitrate by bacteria,
nitrogen percentage in atmosphere
78.08%
symbiotic N2 fixation
rhizobia, legume family, non-legumes (black alder, water fern), white clover - give plant nitrogen, grows a lot and has symbiotic relationship with n2 fixing bacteria
non-symbiotic N2 fixation
free living bacteria in soil (azotobacter, clostridium), cyanobacteria in aquatic systems
nitrogen transformation in soil
nitrification (aerobic), denitrification (anaerobic), ammonia volatilization (pH>7), nitrogen leaching (nitrate from soil to groundwater)
human impacts on N cycling
too much N in agriculture, animal/food wastes improperly treated, cars, power plants all leads to high N in groundwater and increased atmospheric deposition
oxygen percentage in atmosphere
20.95%
major sources of O2 in atmosphere
photodissociation of H2O (photolysis) and photosynthesis
ozone
pollutant - smog and damaging to life forms
sunscreen - prevent excessive UV rays from earth
holes in ozone layer
caused by chemicals like CFCs increase rate of ozone depletion and lead to holes in stratospheric ozone layer
bad ozone
occurs at ground level (troposphere), results from vehicles, industry emissions, also known as brown haze in and around large cities
ozone production in stratosphere
UV breaks O2, free O molecules react with O2 to form O3
natural ozone destruction
UV breaks ozone to O2 and O so free O bumps with O3 and forms two O2.
chemicals that destroy ozone
CFCs (refrigerants, solvents, aerosols - anthropogenic), nitrous oxide (nitrogen fertilizers, sewage), methane (wetlands, landfills)
CFCs depleting ozone
UV hits CFC, causes Cl to break away, Cl hits O3 and forms O2 and ClO, if a free O hits ClO, it will form O2 and free Cl, which goes on to destroy more O3
nitrification
NH4+ -> NO2-
NO2- -> NO3-
denitrification
NO3- -> N2
ammonia volatilization
NH4+ + OH- -> NH3 + H2O
how does N2O deplete ozone?
UV makes N2 and O, if O reacts with N2O, it forms N2 and O2 or 2 NO, and NO depletes O3 to make NO2 and O2
ozone hole definition
where O3 concentration has decreased to <220 DU
