Investigation of Li/Ca variations in aragonitic shells of the ocean quahog Arctica islandica, northeast Iceland
Investigation of Li/Ca variations in aragonitic shells of the ocean quahog Arctica islandica, northeast Iceland
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DOI：
10.1029/2009gc002789
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发表时间：
2009-12
期刊：
影响因子：
3.7
通讯作者：
J. Thébault;B. Schöne;N. Hallmann;M. Barth;Elizabeth V. Nunn
中科院分区：
文献类型：
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作者：
J. Thébault;B. Schöne;N. Hallmann;M. Barth;Elizabeth V. Nunn
锂-钙比的年际和年内变化进行了研究，在文石外壳层的少年Arctica islandica（软体动物;双壳类）在2006年收集活在冰岛东北部的高时间分辨率。Li/Cashell介于7.00和11.12 μmol mol−1之间，并呈现明显的季节性周期，在年生长线处记录了最低值;一般模式是Li/Cashell从3月到5月逐渐增加，然后在6月达到平台，并在7月至8月降至最低值。Li/Cashell与δ 18 O壳衍生温度相关，但这种关系的强度较弱（r2 < 0.25和p < 0.05）。它与微生长增量宽度显着，并与最近的河流之一的流量。Li/Cashell的季节变化islandica最有可能被解释为（1）钙化率和/或（2）积雪融化后，富含锂的硅酸盐颗粒大量流入河流，流入大海。在第一种情况下，Li/Cashell可能是一个有用的代理，用于解决双壳类的生长速度的季节性变化，缺乏可辨别的microgrowth模式。Li/Cashell的突然降低反过来可以帮助识别由于恶劣环境条件导致的生长延迟。或者，如果锂/Cashell的变化与颗粒锂输入河流，这可能是一个新的代理冰岛玄武岩的机械风化强度，有趣的观点重建的频率和强度过去jökulhlaups（冰下爆发洪水）。需要进一步的工作，包括实验研究，来验证这些假设。
Interannual and intra‐annual variations in lithium‐to‐calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile Arctica islandica (Mollusca; Bivalvia) collected alive in 2006 off northeast Iceland. Li/Cashell ranged between 7.00 and 11.12 μmol mol−1 and presented well‐marked seasonal cycles with minimum values recorded at the annual growth lines; a general pattern was a progressive increase in Li/Cashell from March to May, followed by a plateau in June and a decrease down to minimum values in July–August. Li/Cashell was correlated with δ18Oshell‐derived temperature, but the strength of this relationship was weak (r2 < 0.25 and p < 0.05). It covaried significantly with microgrowth increment width and with the discharge from one of the closest rivers. Seasonal variations of Li/Cashell in A. islandica may most likely be explained (1) by calcification rate and/or (2) by significant river inputs of Li‐rich silicate particles flowing to the sea as soon as snow melts. In the first case, Li/Cashell may be a useful proxy for addressing seasonal variations of growth rate in bivalves that lack discernable microgrowth patterns. Abrupt decreases of Li/Cashell may, in turn, help identify growth retardations due to harsh environmental conditions. Alternatively, if Li/Cashell variations are linked to particulate Li inputs by rivers, this could be a new proxy for the intensity of mechanical weathering of Icelandic basalts, with interesting perspectives for the reconstruction of frequency and intensity of past jökulhlaups (subglacial outburst floods). Further works, including experimental studies, are needed to test these hypotheses.