Notes from “Isotopes in QUEST” meeting, Cambridge 28th November 2006

Carbon isotopes

Process Implications for C Cycle Issues for d¹³C

0. Circulation P

1. Carbonate speciation P                                    OCHIM Ks ?

2. Air-sea exchangeP                                           Peacock                                In + out difference for d¹³C

3. Biological pump (Rau)P ?                                 Fe limitation                           Check parameterization; is constant alpha correct (with ecosystems later)

4. Fractionation into CaCO3                                                                              Inorganic P Species, pH/Carbonate for effect (Spero)

      - Fluxes of C by inorganic fractionation

      - Values in substances are more complicated                                                  Symbionts?, Benthic vs planktic, [infaunal vs. epifaunal - eventually?]

                                                                                                                           Mackensen effect

5.   Dissolution and mixing in sediment                                                                  Do this eventually to allow comparison with down-core records

ACTION:  Kevin to check parameterization of processes 0 to 3 and re-encapsulate Rau model which Andy thought was present weakest aspect of the model.

Oxygen isotopes

0.   Circulation – ABW?

1.   Ice Sheets – including δ¹⁸O of ice + melting

2.   Ppt + run off δ ¹⁸ O map              – Full atm à HadCM à not for us- too slow

                                                         -- Borrow someone elses

                                                         -- Parameterize  eg versus salimity à Maybe best for ocean process

3. Calcification à depth, T, species, pH

Data Complilation

Water – column

1.   POC δ¹³C sediment tows – (need to watch out for industrial d¹³C)                                                              Kevin/Andy

2.   DIC δ¹³C –         GEOSECS, WOCE (maybe via GLODAP - Rob Key)                                                             Kevin

                                 EU data from Pangea and/or Mackenson                                                          Ros (to contact Bijma)

3.   δ¹⁸C – Schmidt, Rohling, Bigg – NASA – should be already done

Sediment

Forams - δ ¹⁸ C, δ ¹³ C NOAA, Pangea, Oppo, Delphi, Sarnthien                                                                  Babette/Kevin

Time-range: 150 – 0 kyr

Species:  All plantitics except universa

Related data: lat, long, depth, lab, standard dev of rtd, size fraction, # of individuals, water properties, sedimentation rate, other data from same samples

Model targets:

Initially two timeslices:  modern (5 – 0 to yr); LGM (23 – 18 to yr – calender).

Glacial-interglacial CO₂ change scenarios we might test with model against compiled data:

1.         S. Ocean Sea Ice (Stephens + Keeling)

2.         N. Shift westerlies (Toggweiller)

3.         Stratification (Francois + Sigman)

4.         Buoyancy (Watson)

5.         Fe Fertilization (Martin)

6.         Rain rate ratio (Archer) (inc. opal/Cc ration, ballast etc)