Parameter
Proxy
Basic assumption(s/ Empirical relationship
Selected reference(s}'
Biological Properties
nutrient
29
P-accumulation
P-flux is related 10
see 35
Filippelini and Delaney
availability
Corg flux via Redfield
(1994);
( concentraratio
Delaney and Filippelini
tion)
(1994)
30
Ii13C
I) the CO, fixing
[PO,]
= a
* Ii\3C
Bergeret al. (1978)
enzyme of marine
phyto-plankton
where: a
= (6.813Cphot
*
(RUBISCO) has a
CIP",)/[LCO,l
=higher affinity for
l2c.
0.93%o/~oVkg
Hence, increased
primary production
(Broecker and Peng
enriches ocean surface
1982)
waters in i3C
2) Foraminifer shell
~PC is a robust tracer
for S!3CDlC
31
Cd/Ca
Cd is actively
[PO,]
= a
* Cd/Casw
Boyle (1976,1988,
accumulated by
1992); Frew and Hunter
phytoplankton
where: Cd/Cashell
= b
* (1992); Saager and de
(possibly in
Cd/Casw
Baar (1993); de Baar et
polyphosphate bodies:
al. (1994)
PPBs). Hence, Cd and
e.g. b
= 1.9 for G.
P04= covary
bulloides (Mashiotta et
a!. 1997)
Precision (lab.
Accuracl
reproducib.)
< 10 %
oflhe
< 10 %
of the
reactive P
accumulation
concentration
rate value
0.03%, (=00.06
?
~oVkg)
±1.5pM
?
(Saager 1994)
Pitfalls
link between P and C burial needs
further investigation
1) preformed nutrient-tracer
relationship may not be constant
2) Ii 13
C-LCO, slope may not be
constant over time
3) thermodynamic equilibration
(sea-air exchange)
4) contamination with terrigenous
Corg
5) carbon transfer between terr.latm.
and the oceanic reservoir
6a) vital effects (respiration,
photosynthesis,
[Cot], T,
"Mackensen effect" (Mackensen et
al. 1993), GAM-<:alcification,
"crusting")
6b) isotopic fractionation in planktic
foraminifera is quite well
understood (Wolf-Gladrow et al.
1999; Zeebe et al. 1999)
8) potential for significant
diagenesis
(dissolutionlrecrystalization)
I) Cd-PO," slopes vary regionally
2) CdIP ratio may vary with time
3) anoxia
4) Cd residence time ±? ky
5) effects of dissolution (McCorkle
et aJ. 1995)
-0\
N
~
(t>
...,
~
~