Re-examination of the temperature-dependent relationship between delta 18Odiatoms and delta 18Olake water and implications for paleoclimate inferences

• Published in: Journal of paleolimnology 2010-08, Vol.44 (2), p.547-557
• Main Authors: Crespin, Julien, Sylvestre, Florence, Alexandre, Anne, Sonzogni, Corinne, Pailles, Christine, Perga, Marie-Elodie
• Format: Article
• Language: English
• Subjects: Bacillariophyceae
• ISSN: 0921-2728
• DOI: 10.1007/s10933-010-9436-2

The oxygen isotope composition ( delta 18O) of diatoms is commonly used for paleoclimate reconstruction. There is, however, no consensus regarding the equilibrium isotopic fractionation factor between diatom silica and the water in which it is precipitated. We re-examined the temperature-dependent relationship between delta 18Odiatoms and delta 18Olake water from Lake Annecy (France). A temperature coefficient of -0.16/ degree C (R 2 = 0.51) was determined, supporting findings from previous calibration studies. However, regression lines obtained from different calibration studies, though displaying similar slopes, were shifted. In this manuscript, we propose that several factors, including selected variables (temperature, delta 18Olake water), analytical techniques, the impact of diagenetic processes and biological effects, may influence the silica-water fractionation factor for diatom silica. The similar magnitude of the diatom-temperature coefficients determined across studies is promising, supporting its use as a valuable tool for interpreting variations in delta 18O values from fossil lacustrine diatoms in temperate lakes. With respect to paleoclimatic applications, the temperature-dependent relationship yielded uncertainties of -3 degree C on reconstructed temperatures and -0.5 on delta 18Olake water.