Download Water Cycle

Biogeochemical Cycles
o Energy Flows Through Ecosystem
o Water—Nitrogen—Carbon—Phosphorus Are Recycled!
o They Move Thru A Biogeochemical Cycle:
o Abiotic (Non-living) Portion Of Environment (Atmosphere) 
Living Thingsthen Back Again
Water Cycle
o Cells Contain 70-90% H20
o Very Little Of Earths Available
H20 Is In Living Things
o Rivers / Lakes / Streams /
Oceans Contain A Big %
o Atmosphere Contain Water =
Water Vapor
o Ground Water = In Soil Or
Underground In Porous Rock
o Water Cycle = Movement Of
H20 between Reservoirs
o Evaporation
o Transpiration
o Precipitation
Evaporation
o Adds H2O vapor to
atmosphere
o Heat causes water to
evaporate
o 90% of evaporated
water from terrestrial
ecosystem passes
through plants in a
process called….
transpiration
Transpiration
o Plants take in H2O thru roots
o Release water & take in CO2
(carbon dioxide)
o Animals drink/ eat to take
in H2O
o Animals release it when:
o Breathing
o Sweating
o Excretion
Precipitation
o Water leaves atmosphere
o Temperature & air
pressure (abiotic factors)
determine how much water
can be held
o Once atmosphere is
saturated w/vapor = snow,
rain, sleet, hail or fog
Carbon Cycle
o Photosynthesis + cellular respiration
o Photosynthesis = plants & other autotrophs use:
o CO2 + H2O & sunlight = carbohydrates
CELLULAR RESPIRATION
o Process in which
autotrophs & heterotrophs
use oxygen (O2) to
breakdown carbs.
o Cells make ATP (energy) by
breaking down organic
compounds
o A compound that results from
living things & contains carbon
HUMAN INFLUENCE ON THE CARBON CYCLE
o In the past 150 years CO2 in the atmosphere has
risen 30% almost ½ in the last 40 years
o Due to human activity
o Burning fossil fuel:
o Remains of organisms
that have been transformed
by decay, heat, & pressure  Energy rich organic
molecules
o Burning releases
energy & CO2
o Burning vegetation
releases CO2
o Tropical rainforest
destruction
o With no plants CO2
is not absorbed
Nitrogen Cycle
o Nitrogen is needed to make proteins & nucleic acids:
o Organic molecule, DNA or RNA, that stores & carries
important info for cell function
o N2 (nitrogen gas) makes up 78% of the atmosphere
o N2 is however limited to ammonia (NH3)for most
living things
NITROGEN FIXATION
o Conversion of N2 to ammonia
o Certain bacteria can convert  NH3 =
nitrogen-fixing bacteria
o Live in soil & in
some roots
Recycling Nitrogen
o Bodies of dead organisms contain “N”
o Urine & dung
o Decomposers break down corpses & waste of
organisms give off nitrogen as ammonia =
ammonification
o Nitrification = bacteria in soil take in ammonia &
oxidize it into nitrites, NO2 & nitrates, NO3
Back into the environment
DENITRIFICATION
o Returning nitrogen to atmosphere
o Plants can absorb nitrates & ammonia from soil
o Animals cannot!
o Animals obtain it
by eating other
organisms
o They digest the proteins & nucleic acids
Phosphorus Cycle
o The phosphorus cycle may also be referred to as
the mineral cycle.
o Phosphorus is mainly found in water, soil, and
rock.
o Phosphorus is essential for life.
o Component of DNA
o Building block of our bones and teeth.
Phosphorus Cycle
o Unlike the other cycles, phosphorus cannot be
found in air in the gaseous state.
o The phosphorus cycle is the SLOWEST cycle.
o Phosphorus is most commonly found in rock
formations and ocean sediments as phosphate
salts.
o Phosphate salts that are released from rocks
through weathering usually dissolve in soil water
and will be absorbed by plants.
o Animals absorb phosphates by eating plants or
plant-eating animals.
o When animals and plants die, phosphates will
return to the soils or oceans again during
decomposition.
o After that, phosphorus will end up in sediments or
rock formations again, remaining there for
millions of years. Eventually, phosphorus is
released again through weathering and the cycle
starts over.
Human Imapcts on the Phosphorus Cycle
• Like nitrogen, increased use of fertilizers
increases phosphorus runoff into our
waterways.
REMEMBER THIS!!!
• Most phosphorus is found in rocks and soil.
• The phosphorus cycle is the slowest cycle.
• Excess phosphorus contributes to
eutrophication.