Estimation of net accumulation rate at a Patagonian glacier by ice core analyses using snow algae
Estimation of net accumulation rate at a Patagonian glacier by ice core analyses using snow algae
复制标题
DOI：
10.1016/j.gloplacha.2006.11.014
复制
发表时间：
2007-10
影响因子：
3.9
通讯作者：
S. Kohshima;N. Takeuchi;J. Uetake;T. Shiraiwa;R. Uemura;N. Yoshida;S. Matoba;M. Godoi
中科院分区：
文献类型：
--
作者：
S. Kohshima;N. Takeuchi;J. Uetake;T. Shiraiwa;R. Uemura;N. Yoshida;S. Matoba;M. Godoi
对南巴塔哥尼亚冰原廷德尔冰川（50°59′05″S，73°31′12″W，1756 m a.s.l.）45.97米长冰芯中的雪藻进行了检查，以了解其在冰芯测年和净积累率估计中的潜在用途。在现场对岩心进行了目视地层观察和堆积密度测量，随后对雪藻生物量、水同位素 (18O、D) 和主要溶解离子进行了分析。冰芯含有许多藻类细胞，这些藻细胞属于生长在靠近地表的雪中的两种雪藻：氯单胞菌。以及一种未知的绿藻物种。藻类生物量和主要溶解离子（Na+、K+、Mg2+、Ca2+、Cl−、SO42−）在上部 3 m 处表现出快速减少，可能是由于融水洗脱和/或藻类细胞的分解。然而，雪藻生物量、18O、D-过量和主要离子仍然存在季节性循环，尽管循环的幅度随着深度而减小。假设几乎没有雪藻的层是没有藻类生长所必需的融水的冬季层，我们估计该位置从1998年冬季到1999年冬季的净积累率为12.9 m a−1，从初冬到1999年12月为5.1 m。这些估计值与根据18O峰值估计的值（1998年夏季到1999年夏季为17.8 m a−1）相似。 1999 年夏季和 1999 年夏季至 1999 年 12 月期间为 11.0 m）和 D 超标（1998 年秋季至 1999 年秋季为 14.7 m a−1，1999 年秋季至 1999 年 12 月为 8.6 m a−1）。这些值远高于巴塔哥尼亚过去冰芯研究获得的值，但与巴塔哥尼亚冰川消融区域的各种观测预测的值处于同一数量级。
Snow algae in a 45.97-m-long ice core from the Tyndall Glacier (50°59′05″S, 73°31′12″W, 1756 m a.s.l.) in the Southern Patagonian Icefield were examined for potential use in ice core dating and estimation of the net accumulation rate. The core was subjected to visual stratigraphic observation and bulk density measurements in the field, and later to analyses of snow algal biomass, water isotopes (18O, D), and major dissolved ions. The ice core contained many algal cells that belonged to two species of snow algae growing in the snow near the surface: Chloromonas sp. and an unknown green algal species. Algal biomass and major dissolved ions (Na+, K+, Mg2+, Ca2+, Cl−, SO42−) exhibited rapid decreases in the upper 3 m, probably owing to melt water elution and/or decomposition of algal cells. However, seasonal cycles were still found for the snow algal biomass,18O, D-excess, and major ions, although the amplitudes of the cycles decreased with depth. Supposing that the layers with almost no snow algae were the winter layers without the melt water essential to algal growth, we estimated that the net accumulation rate at this location was 12.9 m a−1from winter 1998 to winter 1999, and 5.1 m from the beginning of winter to December 1999. These estimates are similar to the values estimated from the peaks of18O (17.8 m a−1from summer 1998 to summer 1999 and 11.0 m from summer to December 1999) and those of D-excess (14.7 m a−1from fall 1998 to fall 1999 and 8.6 m a−1from fall to December 1999). These values are much higher than those obtained by past ice core studies in Patagonia, but are of the same order of magnitude as those predicted from various observations at ablation areas of Patagonian glaciers.