4. How are the granules produced?
• Calciferous glands;
• Milky fluid;
• → CaCO3 concretions;
• → granules.
Darwin (1881) / Canti (1998)
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5. Why do they produce them?
• “It is probable that they primarily
serve as organs of excretion, and
secondarily as an aid to digestion”
(Darwin, 1881);
• Egg formation?
• Triturate food in gizzard?
• Absorption of food products?
• Water regulation → evolutionary
adaptation to terrestrial habitat?
• Respiratory organ / eliminate
excess CO2?
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6. Aim
To construct a new terrestrial isotope–temperature
curve for application to earthworm secreted
calcium carbonate granules.
→ Potential for granules in dating and
palaeoenvironmental interpretation.
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19. Conclusions
• Lumbricus terrestris produce calcite granules;
• These are enriched in 18O by 1.5 ‰ compared to
equilibrium;
• δ18Ocalcite values depend on temperature and
δ18Owater values following:
1000 ln α = 18.47 (103 T-1) – 32.46
• Well-preserved archaeological granules can be
used as palaeothermometers.
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20. Future work
• Influence of evaporation with depth?
• Changes of temperature with depth?
→ Analyse recent granules along soil profiles
Canti (2007)
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21. Future work
• Analyse more replicates
• δ13C values: soil organic matter, DOC, earthworm tissues,
milky fluid;
• The influence of [CO2] on granule production;
• δ18O internal structure heterogeneity: ion probe;
• Application to soil archaeological and geological
samples:
– Reconstruction of past temperatures;
– Dating of samples by U/Th;
– Comparison with pedogenic carbonate concretions and Bithynia
tentaculata opercula.
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22. Thank you!
Questions?
Acknowledgements:
• NERC
• Yan Gao
• Matt Canti (English Heritage)
God makes the earthworm
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