Transcript biogeochemical cycles ppt

Chemical/Nutrient
Recycling in
Ecosystems
1
DO Now
1.In addition to energy,
what do organisms need to
survive?
Matter
• Anything that has mass and
takes up space
• Matter is recycled in
ecosystems
• What is matter composed of?
Levels of organization in the biosphere
Levels of organization in the biosphere
Elements in Living Things
• The elements found in significant
amounts in organisms are
– Carbon
– Hydrogen
– Oxygen
– Nitrogen
– “HONC” HONC if you love science!
• Also phosphorus and sulfur
• “HONC-PS”
Law of Conservation of
Mass
• Matter is neither created nor
destroyed!
• So what happens when matter
seems to just “appear” or
“disappear”?
What happens to matter
in the biosphere?
• Matter is recycled by
naturally occurring
chemical reactions!
QuickTime™ and a
decompressor
are needed to see this picture.
• What four elements primarily make up
living organisms? Hydrogen, Oxygen,
Nitrogen, Carbon
• These elements (along with others
such as _sulfur__ and _phosphorus_
are the basis of life’s most important
compounds: water, carbohydrates,
lipids, nucleic acids and proteins
9
CYCLES OF MATTER
• In other words, a handful of elements
combine to form the building blocks of
all known organisms.
• However, organisms cannot
manufacture these elements and do not
“use them up”.
• Where these essential elements come
from?
CYCLES OF MATTER
Unlike the one-way flow of energy,
matter is recycled within and
between ecosystems
BIOGEOCHEMICAL CYCLE
• Process in which elements, matter is
passed from one organism to another.
• As matter moves through these cycles,
it is transformed which means that it is
never created or destroyed, just
changed.
The Water
Cycle
The Carbon and
Oxygen Cycles
The pathway of carbon and
oxygen through an
ecosystem
14
The Carbon and Oxygen
Cycles
1. Almost all oxygen in Earth’s
atmosphere originally came from the
photosynthetic activities of plants
2. How do C and O cycle through the
biosphere?
• 2 processes – PHOTOSYNTHESIS
AND CELLULAR RESPIRATION
The Carbon and Oxygen
Cycles
Carbon Cycle
• How have humans affected the carbon
cycle?
• What processes are putting too much
carbon dioxide into the atmosphere?
• What problem does this lead to?
17
The Nitrogen
Cycle
The pathway of
nitrogen through an
ecosystem
18
Nitrogen is an important
element in living things
• Used to make proteins and nucleic acids!
• Nitrogen gas (N2) makes up 78% of the
earth’s atmosphere
• However…most organisms cannot use N2
directly
• Why can’t organisms use N2 directly?
How do plants get nitrogen?
• Rely on Nitrogen Fixing Bacteria!
• These bacteria live in the roots of some
plants (legumes – peas, peanuts, beans)
and in the soil
• These nitrogen fixing bacteria are the
only organisms that can “fix”
atmospheric nitrogen into a usable form
(ammonia)
20
Plants and
Nitrogen Compounds
• So, nitrogen is obtained by plants either
directly from the bacteria in their roots,
or in the soil
• Some nitrogen in the soil also comes
from decaying matter – decomposers
break down waste and dead organisms
into usable forms of nitrogen
What are the usable forms of
nitrogen?
• Most plants use nitrogen in two inorganic
forms to make proteins
– NH3 (ammonia) and NO3- (nitrate)
22
• Animals must eat plants to meet their
nitrogen needs
• So, what organisms are absolutely
necessary for the nitrogen cycle to
continue?
– BACTERIA!!
How does nitrogen get
back into the atmosphere?
Other bacteria convert nitrates back into
nitrogen gas. This process is called
DENITRIFICATION.
• Atmospheric nitrogen fixation – a
relatively small amount of nitrogen gas
is converted into usable forms by
lightning
25
The Nitrogen
Cycle
The Phosphorus Cycle
• Movement of phosphorus from
environment to organisms and back to
environment
• P is needed to form bones and teeth in
animals
• P is needed to form nucleic acids
27
How do plans and animals get
phosphorus?
• Plants get it from soil and water
• Animals get it by eating plants or other
animals that have eaten plants
• Slow cycle, does not usually involve
atmosphere
28
How does P enter soil?
• When rocks erode, a little P dissolves
as phosphates in soil and water
• P added to soil and water when excess
p is excreted in waste from organisms
and when organisms die and
decompose
29
How do plants and animals
get phosphorus?
• Plants absorb phosphates in the soil
through their roots
• Animals eat plants
• Some p washes off land and ends up in
oceans
• Many phosphate salts not soluble in
water, so they sink to bottom of ocean
and accumulate as sediment
30
How do humans affect
phosphorus and nitrogen
cycles?
• Fertilizer use!
31