Embed Size (px)
DESCRIPTION
September 30, 2013. Earth System History GEOL 1020. [ 15] Announcements More about global geochemical cycles. About plants and carbon fixation…. THIS DIFFERENCE IN BEHAVIOR OF THE BOND STRENGTHS, CAN BE TRACED USING CARBON ISOTOPES!!. The photosynthesis-respiration cycle in plants. - PowerPoint PPT Presentation
Citation preview
Earth System HistoryGEOL 1020
[15]Announcements
More about global geochemical cycles
September 30, 2013
About plants and carbon fixation….
The photosynthesis-respiration cycle in plants.
THIS DIFFERENCE IN BEHAVIOR OF THE BOND STRENGTHS, CAN BE TRACED USING CARBON ISOTOPES!!
KNOW THISBIOLOGICAL SYSTEMS PREFER THE LIGHT ISOTOPE OF CARBON (12C) OVER THE HEAVY ISOTOPE (13C).
What is the relationship between burial of plant debris and atmospheric chemistry?
The CO2 and O2 system
CO2 DOWN O2 UP
CO2 UP O2 DOWN
Respiration “BURNS” organic matter back to CO2
And consumes Oxygen in the process…
OXIDATION
CO2 formation
Rapid burial of organicmatter cuts it off from oxygen, therefore no feedback to CO2!!
KNOW THIS:
13C / 12C ratio in atmosphere is steady here.
13C / 12C ratio in atmosphere is increasing here!
PREFERSCARBON-12
Carbon-12 enrichedOrganic matter getsBuried.
Carbon-12 getsDepleted in atmosphere
Case Study: Increased plant growth and/or increased carbon burial
Oxygen startsto build up.
What is the relationship between burial of plant debris and atmospheric chemistry?
The CO2 and O2 system
CO2 DOWN O2 UP
CO2 UP O2 DOWN
Time (samples from bottom to top)
Am
ount
of
CO2 in
at
mos
pher
e
Case Study: Decreased plant growth and/or decreased carbon burial
TEMPERATURE??
IS IT GETTING HOTTER OR COLDER WITH TIME?
A. COLDER
B. HOTTER
time
CO2 in
at
mos
pher
e
Case Study: Decreased plant growth and/or decreased carbon burial
TEMPERATURE!!
IS IT GETTING HOTTER OR COLDER OUTSIDE?
A. COLDER
B. HOTTER
BECAUSE CO2 IS A GREENHOUSE GAS, IT TRAPS WARMTH AND WARMS THE AIR
time
OXY
GEN
LE
VELS
?
time
13C/
12C
In a
tmos
pher
e &
sed
imen
ts
Case Study: Decreased plant growth and/or decreased carbon burial
OXYGEN LEVELS?
A.
B.
C.
time
OXY
GEN
LE
VELS
?
time
13C/
12C
In a
tmos
pher
e &
sed
imen
ts
Case Study: Decreased plant growth and/or decreased carbon burial
OXYGEN LEVELS?
C.
OXIDATION
CO2 formation
Returns Carbon-12 to atmosphere
Rapid burial of organicmatter cuts it off from oxygen, therefore no feedback to CO2!!
KNOW THIS:
13C / 12C ratio in atmosphere is steady here.
13C / 12C ratio in atmosphere is increasing here!
Mid-Cretaceous
RECALL: if CO2 goes down, O2 goes up
if O2 goes down, CO2 goes up
More organic carbon burial = left-over HEAVY carbon in atmospheric CO2.
With increasing burial of organic matter, or increasing FLUX (input) into sedimentary reservoir, CO2 level goes DOWN
13C / 12C ratio in atmosphere is steady.
13C / 12C ratio in atmosphere is increasing!
13C/12C ratio changes over time
COLD
WARM
In the marine system, the same relationship between increased burial of organic matter in INCREASE in the stable carbon isotope ratio (13C/12C) holds!
