Organic Carbon, Nitrogen, and Phosphorus
Cycles and the composition of marine phytoplankton
1. C, N, P cycles
2. Major biochemicals in marine phytoplankton
3. Introduction to dissolved organic carbon
TOC in the N. Passic
Particulate organic carbon (POC)
and
Dissolved organic carbon (DOC)
- -
PARTICULATE
w
BACTERIA
DlSSOLVED
-MESO. MICRO. NANO. PICO- PtANKTON
COLLOlDAL
I
I
I
3
1OOmm
From Peltzw and Hayward. 1996
IOmm
-
1mm
i
100nm
IOnm
0.fmm
0.3 nm
.O.OOl mm
0
1
POC
IiDOC
TOA
-e
THE NITROGEN CYCLE
Nitrogen Cycle
Fixation
-2
NH4+
Norg
N2
Fixation
(lightning)
N2
N2O
+1
Denitrification
Bacteria in
Nodules
N Fixing Bacteria
Nitrate Bacteria
Fertilizer Factory
NO3
Plants
Animals
Decay and waste
NO2
Nitrite Bacteria
n
+5
NO2-
atio
+4
c
rifi
+3
NO
nit
+2
Nitrification
0
N reduction
-1
De
Oxidation state of Nitrogen
-3
NO3-
NH4+
Decomposers
Figure by MIT OCW.
GLOBAL NITROGEN FIXATION (GT N/YR)
Industrial
0.05
Fossil Fuel Combustion
0.02
Lightning
0.01
Agriculture
0.09
Forests, etc.
0.05
Ocean
0.04
Figure by MIT OCW.
THE NITROGEN CYCLE (Tg N/year)
Denitrification 30
Outgassing 1
Atmosphere
NOx Dep
36
N2 Fix
150
NH3 Dep 89
N2fix 40
Ind
Fix Microb
NH3
NOx
40
Denit
Vol
8
147 122
NH3
Dep
23
Terrestrial
Weathering 5
Crust
Rivers
34
NOx
Dep
11
Ocean
Sedimentation 14
Figure by MIT OCW.
Figure by MIT OCW.
Dissolved Nitrogen (pM)
at HOTS
,... . .
0
ni
lo
20
30
40
SO
I
+ Nitrate
Dissolved organic Nitrogen
Preservoirs and Cycling in the Ocean
Atmospheric Input:
1 x 1010 mol p yr-1
Riverine Input (TDP):
10
-1
3.15 x 10 mol p yr
SNP
Protozoa
Bacteria
Microbial
Food Web
Euphotic Zone
SRP
Zooplankton
0-150 m
Fish
Phytoplankton
Aggregation and Sinking of Particulate
Organic Matter
Occanic P Reservoir
3.2 x1011mol P
Upwelling
Sedimentary P Reservoir
1.3 x1011mol P
150-6000 m
10
-1
P Burial: 11-34.1 x 10 mol P Yr
The pre-anthropogeric marine Pcycle. see text for detaills on fluxes.
Figure by MIT OCW.
Chlorophyceae
(green algae)
Tetraselrnis rnaculata
Dunaliela salina
Chrysophyceae
(golden brown algae)
Monochrysis lutheri
Syracosphae ra carterae
Protein
72
58
53
70
Bacillariophyceae
(brown algae, diatoms)
Chaetoceros sp.
68
Skeletonerna costaturn
58
Coscinodjscz~ssp.
74
Phaeodac tylurn tricornu turn 49
Dynophyceae
(dinoflagellates)
Arnphidiniurn carteri
Exuriella sp.
35
37
Average
57
Carbohydrate
Lipid
Ash
Proteins
proreins serve as eminyes
and structural compomtsof cells
CH2
H2C
O
CH
RUBISCO
fixes
in photsynthesis
Figure
by MIT OCW.
CH
CH
RUBISCO
fixes CO2 in photsynthesis
C
C
H
CH2
O
C
N
H
C
H
N
CH2
Methionine
S
CH2
amino acid
R-C-COOH
I
NH2
O
C
C
H
O
C
N
H
O
CH2
H
C
H
N
C
CH2
HC
HC
C
C
OH
CH
CH
C
H
N
H
O
Tyrosine
PEPTIDE
polymers
Figure by MIT
OCW. of amino acids
UN = 4, 80% of all nitrogen in marine algae
250% clf the carbon
Figure by MIT OCW.
Amino Add Cmpdtlaa wf
A l p
hCowynmdCnmkr~l%6)
Picture removed due to copyright restrictions.
Palysaccharide analysis
Polysaccharide Analysis
2
3
1
O
H+ 1
2
3
0
O
2 Fructose, Glucose
3 Sucrose
4
hydrolysis
56
7
O
H+
hydrolysis
8
4
Minutes
Figure by MIT OCW.
Lipid biosynthesis occurs via two pathways
1) polyketide
polymerization of acetate I(CH3000H). products usually have an even number of carbons
2) imprenoid
polymerization of isoprene a five carbon H C Products have 10,15,20,rarbns
(head)
Figure removed due to copyright restrictions.
Source Unknown.
Terrestrial Plant organic components
Lignin is a complex
structural polymer of
hydroxycinnamyl alcohols
that are linked together in a
number of different linkages
and patterns Lignin and
cellulose make up a large
percentage of the carbonin
woody and nonwoody tissues
of higher plants.
Figure by MIT OCW.
DIN vs DIP,and TDN vs TDP at station ALOHA
Nitrogen (µM)
30
20
10
0
0
0.4
0.8
1.2
Phosphorus (µM)
1.6
2
Figure by MIT OCW.
Nitrogen versus phosphorus correlations for samples collected in the upper 0-400 m of the water column at Sta. ALOHA
during the period October 1988 to December 1997. The bottom line is for nitrate plus nitrite (N+N) versus soluble reactive
phosphorus (SRP) concentrations and the top line is for total dissolved nitrogen (TDN) versus total dissolved phosphorus
(TDP). Model II linear regression analyses: N+N (µM) = 14.62 [14.58 to 14.66] SRP (µM) -1.08 [-1.10 to -1.06], r = 0.996,
n = 3299 and TDN (µM) = 14.57 [14.45 to 14.69] TDP (µM) + 1.50 [1.44 to 1.56], r = 0.981, n = 2060. Values in brackets
indicate the 95% confidence intervals of the respective slope and intercept values.
DON and DOP at station ALOHA,HOTS
0
2
8
10
0
100
100
300
300
500
Depth (m)
Depth (m)
0
DON (µM)
4
6
0
0.1
DON (µM)
0.2
0.3
0.4
500
700
700
900
900
1100
1100
Figure by MIT OCW.
N/P ratios at station ALOHA, HOTS
0
0
N:P (mol:mol)
10
15
5
0
N:P (mol:mol)
10
20
10
N:P (mol:mol)
15 20
25
30
200
Depth (m)
400
600
800
Inorganic
Total
1000
Nitrogen-to-phosphorus (N:P) ratios versus water depth for samples collected at Sta. ALOHA during the period Oct. 1988 to Dec. 1997.
(Left) Molar N:P ratios for dissolved inorganic pools calculated as nitrate plus nitrite (N + N): soluble reactive phosphorus (SRP).
(Center) Molar N:P ratios for the "corrected" total dissolved matter pools. (Right) Molar N:P ratios for total dissolved matter pools,
including both inorganic and organic compounds, calculated as total dissolved nitrogen (TDN) : total dissolved phosphorus (TDP).
As a point for reference, the vertical dashed line in each graph is the Redfield-Ketchum-Richards molar ratio 16N:1P.
Figure by MIT OCW.
Global inventory of DOC
DOC measured by high
temperature catalytic oxidation
(HTCO) method.
Global inventory was measured by
International JGOFS program (680 GT C).
Depth pretty much the same everywhere,
with high surface water values (40-80 uM C)
and low deep water values (40 uM C).
Deep sea concentrations are nearly constant.
Solar
Variability
Solar
Variability
Cosmic Rays
Geomagnetic Field Intensity
14CO
2
Producfi~n
∆ 14C14C
Cycle
14C Distribution
among
Production
C reservoirs
Distribution
among
C reservoirs
Atm
Surf Surf
Bio/Soils
CaCO3 Seds
CaC6, Seds
Deep
I
Deep
Figure by MIT OCW.
Radiocarbon Age of Dissolved Organic Carbon
ACID
DO1'C and 0Ii4Cin the Atlantic Ocean
r
Sargassa Sea DOC
L
SaTgaw Sea DIG
D0I4Cm d D114Cin the Atlantic and Pacific Ocean
I Sergarraa Sea
WC
r Sam8
Sea DIG
Paclflc Ocaan aOC
A
PactflcOceen MC
Radiocarbon measurements show that the average age
of deep sea DOC is > 5000 yr. If the global inventory is
700 GT C, then the annual flux of C to maintain the system
at steady state can be calculated as:
700 GT/ 5000 yr = 0.14 GT C yr-1
The annual input of DOC from rivers is 0.2-0.4 GT C yr-1,
While annual marine primary production is 60-75 GT Cyr-1
Either source adds enough C per year to maintain the system.
So what is the source of oceanic DOC?
Origin of DOC from stable carbon isotopes
Wrap up
The elemental composition (C, N, P, S) of marine and terrestrial
organisms is a reflection of their biochemical composition at the
molecular level.
Marine organisms (in terms of their carbon) are made of
proteins > carbohydrates > lipids > nucleic acids. In terms of N,
70-80% is in proteins. The remaining is distributed between
nucleic acids, carbohydrates, pigments, etc. The proportions of
biochemicals are variable and reflect both environmental factors
And physiological status.
N and P are limiting nutrients in the euphotic zone. Most of
the N and P in the euphotic zone occur as DON and DOP.
It is not known why these reservoirs of organic nutrients exist.
Is the ocean N or P limited???
DOC is the largest reservoir of organic carbon in seawater. >98%
of organic carbon in the ocean is DOC. It has high concentrations
In the euphotic zone indicating net production or at least input.
Values at depth are low (about half surface water values) and nearly
Constant.
Radiocarbon values of DOC are highly depleted, consistent with
An average residence time of 5000-6000 years. Several ocean
Mixing cycles!!! No one knows why, but surely this impacts
Organic nutrients.