Transcript Where can water be found?

How water, gases, and
nutrients cycle throughout our
ecosystems
Cycles
 Many elements in our ecosystem are never lost, but
simply recycled over and over again
 Water – makes up most of living things (we are about
60% water)
 Carbon – element that makes things organic (living)
 Oxygen – needed for cellular respiration
 Nitrogen – needed to make proteins and nucleic acids
Water Cycle Vocabulary
 Hydrosphere – all the water on the Earth from oceans, creeks, streams,
rivers, lakes, ponds, etc.
 Transpiration – The water that evaporates from the surface of leaves
 Condensation – when water cools from its gaseous state to form a liquid
again
 Evaporation – when
the surface of water
vaporizes to become a
gas
 Precipitation – water
falling to the Earth over a
certain period of time
Water Cycle
 Water is never lost, it is just recycled through the atmosphere
and organisms
 Animals and plants are composed mostly of water, but when
these organisms are eaten or die this water is passed on to the
organism that eats it.
 Much of the water we drink is recycled back into the
environment as urine or sweat.
 The environment recycles water as well through a cycle of
evaporation, condensation, and precipitation.
Carbon Oxygen Cycle
 Carbon dioxide is taken in by plants
 During photosynthesis plants break down the carbon dioxide and
add some more elements (carbon, oxygen, and hydrogen) to
create glucose (C6H12O6)
 We then eat plants and break down that glucose for energy (ATP)
in a process called cellular respiration. The carbon molecules we
take from the glucose are
then exhaled as carbon
dioxide that plants can use.
 Plants also give off the
oxygen we need to perform
cellular respiration because
it is a waste product of
photosynthesis
Carbon Oxygen Cycle
 It is not just plants and animals that contribute to this cycle
though . . .
 Decomposers release carbon dioxide when they break down
dead matter
 Anytime something is
burned carbon dioxide is
released and oxygen is
consumed
 Volcanic activity also releases
carbon dioxide into the
atmosphere
 The oceans do absorb some
of our atmospheric CO2
Nitrogen Cycle
 All living things need nitrogen
because all living things contain
nucleic acids (DNA) and amino
acids (proteins)
 Nitrogen is extremely abundant on Earth
because 72% of our atmosphere is made up of
nitrogen, but most organisms are not able to
use gaseous nitrogen (N2)
 Plants need nitrogen in the form of nitrate
(No3-), ammonia (NH3), or urea (NH2)2CO2 to
be able to make proteins and nucleic acids
Nitrogen Cycle
 We get our nitrogen by consuming plants and other animals
which feed on plants
 So, what is converting nitrogen to its different forms?
 Nitrogen fixation
 Decay
 Nitrification
 De-nitrification
Nitrogen Fixation
 Nitrogen fixation is a process
where N2 (atmospheric nitrogen)
is broken apart and the
individual nitrogen atoms are
combined with other elements
 This can occur several ways
 Lightning
 Nitrogen Fixing Bacteria (these can
be found in the soil, living in
symbiotic relationships in the roots
of plants, or in bodies of water)
 Industrially (in plants we heat up N2
and add a catalyst to create ammonia
to be used in fertilizers)
Decay
 Animals consume their nitrogen
and any excess is excreted in the
form of urine and feces
 Animals get their nitrogen by consuming others, so nitrogen
is passed along in the food chain
 When an organism dies the
decomposers break down the dead
material and return nitrogen to the
soil in the form of ammonia
 The decomposers also break down
our wastes into usable forms
Nitrification
 Some ammonia
returned to the soil by
decomposers can be
taken up by plants roots,
but plants prefer
nitrogen in the form of nitrates.
 Nitrifying bacteria convert ammonia to nitrates that plants
can use
 These bacteria live in the soil and in bodies of water
De-nitrification
 De-nitrification is the process by
which nitrates are converted
back into N2 and returned to the
atmosphere
 Once again bacteria called
denitrifying bacteria are
responsible for this process
 Agriculture is responsible for ½
of the nitrogen fixation on
Earth, making it very difficult
for these poor denitrifying
bacteria to keep up!