Coexistence of three calcium carbonate polymorphs in the shell of the Antarctic clam Laternula elliptica
Coexistence of three calcium carbonate polymorphs in the shell of the Antarctic clam Laternula elliptica
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DOI：
10.1029/2011gc003996
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发表时间：
2012-05-24
影响因子：
3.5
通讯作者：
Abele, Doris
中科院分区：
文献类型：
--
作者：
Nehrke, Gernot;Poigner, Harald;Abele, Doris
利用共聚焦拉曼显微镜（CRM）和电子探针（EMP）对沿着南极半岛3个地点的5个南极双壳类Laternula elliptica的贝壳切片进行了分析。L.椭圆石以前被描述为仅由文石组成。现在，CRM绘图显示碳酸钙的三种多晶型物-文石，方解石和球文石-存在于被检查个体的软骨细胞区域。年度壳生长层继续通过文石和球文石，这表明同时矿化的两种多晶型。空间一致的EMP扫描表明，碳酸钙多晶型物影响软骨细胞内镁和锶的分布。据我们所知，这是这三种碳酸钙多晶型物在海洋钙化生物的矿化结构中共存的第一份报告。特别是球文石的存在是出乎意料的，但显示出惊人的相似性，一些鱼耳石。碳酸钙多晶型物对微量元素掺入的强烈影响限制了基于镁和锶的替代物对L.椭圆形。
We analyzed shell cuts of five individuals of the Antarctic bivalve Laternula elliptica from three locations along the Antarctic Peninsula by means of Confocal Raman Microscopy (CRM) as well as Electron Microprobe (EMP). The shell of L. elliptica has been previously described as being composed of aragonite exclusively. Now, CRM mapping reveals that three polymorphs of calcium carbonate - aragonite, calcite, and vaterite - are present in the chondrophore region of the examined individuals. Annual shell growth layers continue through aragonite and vaterite, suggesting simultaneous mineralization of both polymorphs. Spatially congruent EMP scans showed that the calcium carbonate polymorph affects the distribution of magnesium and strontium within the chondrophore. This is, to our knowledge, the first report of the coexistence of these three calcium carbonate polymorphs within the mineralized structures of a marine calcifying organism. Particularly the presence of vaterite is unexpected, but shows striking similarities to some fish otoliths. The strong effect of the calcium carbonate polymorph on trace element incorporation restrict the suitability of magnesium and strontium based proxies for the chondrophore area of L. elliptica.