Profiles of trace elements and stable isotopes derived from giant long-lived Tridacna gigas bivalves: Potential applications in paleoclimate studies
Profiles of trace elements and stable isotopes derived from giant long-lived Tridacna gigas bivalves: Potential applications in paleoclimate studies
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DOI：
10.1016/j.palaeo.2009.06.007
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发表时间：
2009-09-01
影响因子：
3
通讯作者：
Ayling, B.
中科院分区：
文献类型：
--
作者：
Elliot, M.;Welsh, K.;Ayling, B.
本文研究了现代巨型长寿命双壳类动物微量元素分配和稳定同位素组成的环境和生物控制因素，旨在利用这些档案进行古气候重建。首先，通过测量以不同生长速率为特征的不同壳层的时间等效剖面，研究了壳内变率。其次，通过比较从印度太平洋地区不同温度和生产力范围的地点收集的三个现代标本的剖面，研究了遗址间的变异性。这些结果表明，无论生长速率有多大差异，δ O-18剖面在整个壳上都具有很高的再现性。壳层O-18主要由水O-18和温度控制。壳内Mg/Ca分布的比较表明，内层Mg/Ca值比外层和铰链区域高至少23倍，存在明显的系统划分。内层Mg/Ca呈季节性振荡，但随年龄的增长，Mg/Ca的振荡值和振幅增加，叠加在个体发生的趋势上。Sr/Ca剖面在不同壳带中没有明显的可重复的季节趋势。结论是，Mg/Ca和Sr/Ca剖面似乎反映了生物和环境控制的结合，在古气候研究中使用这些代用物之前，需要将其解开。最后，壳内Ba/Ca剖面在所有研究的现代标本中都可以非常详细地重现。站点间比较表明，Ba/Ca峰值的振幅和时间似乎反映了每个地点与浮游植物华相关的叶绿素峰值的时间和振幅，使该示踪剂成为潜在的古生产力指标。爱思唯尔B.V.版权所有
This study investigates the environmental and biological controls on trace element partitioning and stable isotope composition of modern giant long-lived bivalves (Tridacna gigas) with the aim to use these archives for paleoclimatic reconstructions. Firstly, the intra-shell variability is studied by measuring time equivalent profiles in the different shell layers characterised by different growth rates. Secondly, the inter-site variability is studied by comparing profiles derived from three modern specimens collected in sites across the Indo-Pacific region characterised by different ranges of temperature and productivity.These results show that delta O-18 profiles are highly reproducible across the shell regardless of significantly different growth rates. Shell delta O-18 is primarily controlled by water delta O-18 and temperature. Comparison of intra shell Mg/Ca profiles shows a clear and systematic partitioning where inner layer Mg/Ca values are a least 23 times higher than outer layer and hinge areas. Inner layer Mg/Ca shows seasonal oscillations but superimposed on an ontogenetic trend with increasing values and increasing amplitude Mg/Ca oscillations with age. The Sr/Ca profiles do not show clear reproducible seasonal trends in the different shell zones. It is concluded that Mg/Ca and Sr/Ca profiles appear to reflect a combination of biological and environmental controls that will need to be disentangled before using these proxies in paleoclimatic studies.Finally, intra shell Ba/Ca profiles are reproducible in great detail for all modern specimens studied. Inter-site comparison shows that the amplitude and the timing of the Ba/Ca peaks appear to reflect the timing and the amplitude of the chlorophyll peaks associated with phytoplankton blooms at each locality making this tracer a potential paleoproductivity indicator. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.