Silicon isotope composition of diatoms as a paleoenvironmental proxy in Lake Huguangyan, South China

Chen, J., Li, J., Tian, S., Kalugin, I., Darin, A. and Xu, S. (2012) Silicon isotope composition of diatoms as a paleoenvironmental proxy in Lake Huguangyan, South China. Journal of Asian Earth Sciences, 45, pp. 268-274. (doi: 10.1016/j.jseaes.2011.11.010)

Abstract

<p>Silicon is essential for the growth of diatoms, which utilize dissolved silicic acid in lake water and form opaline silica(SiO₂·_nH₂O). During the uptake of dissolved silicic acid, there is a preferential incorporation of light silicon isotope (²⁸Si) into biogenic silica, resulting in the enrichment of heavy silicon isotope (³⁰Si) in dissolved silicic acid. The silicon isotope composition of diatom silica (δ³⁰Si_diatom) may thus record changes in the percentage utilization of dissolved silicic acid by diatoms, which can be then related to other aspects of climate/environment. With the aim of exploring the potential of δ³⁰Si_diatom as an indicator of lacustrine environment, here we made the first measurements of δ³⁰Si_diatom in the sediment core from Lake Huguangyan, a closed crater lake in China. The result shows that δ³⁰Si_diatom varies from −0.6‰ to 1.1‰ and displays broad similarities to variations in contents of biogenic silica and organic carbon throughout the sediment core. δ³⁰Si_diatom is a reliable paleotemperature proxy in Lake Huguangyan, which is supported by good correlation between δ³⁰Si_diatom and available temperature records. Heavier δ³⁰Si_diatom indicates greater dissolved silicic acid utilization at higher temperature while lighter δ3³⁰Si_diatom reflects decreased utilization at lower temperature. The most negative δ³⁰Si_diatom values in the sediment core occur between AD 1580 and 1920, which suggests AD 1580–1920 was the coldest period in Lake Huguangyan over the past 2000 years, thus providing evidence for the existence of the LIA in tropical South China.</p> <p>There are few means by which to reconstruct the history of temperature changes in tropical terrestrial region. δ³⁰Si_diatom, in this study, has proven to be a new promising paleotemperature proxy in lacustrine sediments, and may play important role in reconstructing past temperature changes at low latitude in the future. Detailed investigations on the silicon isotopes of diatoms in more lakes would be desirable in further research.</p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Xu, Dr Sheng
• Authors: Chen, J., Li, J., Tian, S., Kalugin, I., Darin, A., and Xu, S.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Journal of Asian Earth Sciences
• ISSN: 1367-9120
• ISSN (Online): 1878-5786