DOI: 10.5194/cp-8-307-2012
Scopus记录号: 2-s2.0-84858829838
论文题名: The oxygen isotopic composition of phytolith assemblages from tropical rainforest soil tops (Queensland, Australia): Validation of a new paleoenvironmental tool
作者: Alexandre A. ; Crespin J. ; Sylvestre F. ; Sonzogni C. ; Hilbert D.W.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2012
卷: 8, 期: 1 起始页码: 307
结束页码: 324
语种: 英语
Scopus关键词: amorphous medium
; empirical analysis
; functional morphology
; isotopic composition
; numerical model
; oxygen isotope
; paleoenvironment
; phytolith
; plant
; precipitation (climatology)
; rainforest
; silica
; soil type
; soil water
; tropical environment
; uncertainty analysis
; vegetation cover
; Australia
; Queensland
; Bacillariophyta
; Embryophyta
; Tracheophyta
英文摘要: Phytoliths are micrometric particles of amorphous silica that form inside or between the cells of higher plant tissues throughout the life of a plant. With plant decay, phytoliths are either incorporated into soils or exported to sediments via regional watersheds. Phytolith morphological assemblages are increasingly used as proxy of grassland diversity and tree cover density in inter-tropical areas. Here, we investigate whether, along altitudinal gradients in northeast Queensland (Australia), changes in the δ18O signature of soil top phytolith assemblages reflect changes in mean annual temperature (MAT) and in the oxygen isotopic composition of precipitation (δ18Oprecipitation), as predicted by equilibrium temperature coefficients previously published for silica. Oxygen isotopic analyses were performed on 16 phytolith samples, after controlled isotopic exchange (CIE), using the IR Laser-Heating Fluorination Technique. Long-term mean annual precipitation (MAP) and MAT values at the sampled sites were calculated by the ANUCLIM software. δ18Oprecipitation estimates were calculated using the Bowen and Wilkinson (2002) model, slightly modified. An empirical temperature-dependant relationship was obtained: δ18Owood phytolith-precipitation (‰ vs. VSMOW) -0.4 (±0.2) τ (°C) + 46 (±3) (R 2 = 0.4, p < 0.05; n = 12). Despite the various unknowns introduced when estimating δ18Oprecipitation values and the large uncertainties on δ18Owood phytolith values, the temperature coefficient (-0.4 ± 0.2‰ °C-1) is in the range of values previously obtained for natural quartz, fresh and sedimentary diatoms and harvested grass phytoliths (from -0.2 to -0.5‰ °C-1). The consistency supports the reliability of δ18Owood phytolith signatures for recording relative changes in mean annual δ18Osoil water values (which are assumed to be equivalent to the weighted annual δ18O precipitation values in rainforests environments) and MAT, provided these changes were several ‰ and/or several °C in magnitude. © Author(s) 2012. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49610
Appears in Collections: 气候变化与战略
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Recommended Citation:
Alexandre A.,Crespin J.,Sylvestre F.,et al. The oxygen isotopic composition of phytolith assemblages from tropical rainforest soil tops (Queensland, Australia): Validation of a new paleoenvironmental tool[J]. Climate of the Past,2012-01-01,8(1)