| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4731572 | Journal of Asian Earth Sciences | 2012 | 7 Pages |
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 (δ30Sidiatom) 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 δ30Sidiatom as an indicator of lacustrine environment, here we made the first measurements of δ30Sidiatom in the sediment core from Lake Huguangyan, a closed crater lake in China. The result shows that δ30Sidiatom 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. δ30Sidiatom is a reliable paleotemperature proxy in Lake Huguangyan, which is supported by good correlation between δ30Sidiatom and available temperature records. Heavier δ30Sidiatom indicates greater dissolved silicic acid utilization at higher temperature while lighter δ30Sidiatom reflects decreased utilization at lower temperature. The most negative δ30Sidiatom 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.There are few means by which to reconstruct the history of temperature changes in tropical terrestrial region. δ30Sidiatom, 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.
