An 8000-year History of Climate and Environmental Change in Páramo of Central Costa Rica

Methods

Summary

Stable Oxygen Isotope Analysis of Subfossil Chironomid Remains

One of the more promising and novel approaches to reconstructing paleotemperature involves the analysis of the stable oxygen isotope composition (d¹⁸O) in chironomid head capsules (Wooller et al., 2004, 2008; Verbruggen et al., 2010). High Temperature Conversion-Elemental Analyzer (TC/EA) coupled with stable isotope mass spectrometry allows the accurate determination of stable oxygen composition (d¹⁸O) rapidly and precisely.

The d¹⁸O signal extracted from the chitin that comprises larval chironomid head capsules preserved in lake sediment has been shown to reflect the d¹⁸O composition of lakewater, which, in lakes that do not experience significant evaporative enrichment, can be converted to an estimate of mean annual air temperature (MAT).

References:

Wooller, M.J., Francis, D., Fogel, M.L., Miller, G.H., Walker, I.R. and Wolfe, A.P., 2004. Quantitative paleotemperature estimates from δ¹⁸O of chironomid head capsules preserved in arctic lake sediments. Journal of Paleolimnology 31, 267-274.

Wooller, M., Wang, Y., and Axford, Y., 2008. A multiple stable isotope record of late quaternary limnological changes and chironomid paleoecology from northeastern iceland. Journal of Paleolimnology 40, 63-77.

Verbruggen, F., Heiri, O., Reichart, G.J., de Leeuw, J.W., Nierop, K.G.J., and Lotter, A.F., 2010. Effects of Chemical Pretreatments on Delta (Super 18) O Measurements, Chemical Composition, and Morphology of Chironomid Head Capsules. Journal of Paleolimnology 43, 857-872.

Challenges

Stable oxygen isotope analyses are SO SO SO EXPENSIVE!!!