Weight estimates of coccoliths using the optical properties (birefringence) of calcite
Weight estimates of coccoliths using the optical properties (birefringence) of calcite
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DOI：
10.2113/gsmicropal.51.4.289
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发表时间：
2005-01-01
影响因子：
1.5
通讯作者：
Beaufort, L
中科院分区：
文献类型：
--
作者：
Beaufort, L
颗石藻是浮游植物中为数不多的能钙化的生物之一。尽管它们与浮游有孔虫一起在开阔海洋中主导方解石的生产，但它们分泌的方解石量很难确定。在沉积过程中溶解的以球晶石形式存在的方解石的量也很难估计，因为由沉积的球晶石代表的方解石的量也很难估计。由于其微小，球石不能直接称重。而不是.必须使用间接方法来估计它们的重量。我在这里描述一种方法，可以快速估计单个球石的重量。基于在交叉偏振光下观察时它们的亮度的测量。这种双折射方法仅适用于太阳石属（Heliolithae）（不包括颗石科中产生的一些颗石）。对于颗石科和一些直石科，可以使用校正因子来估计重量。双折射法具有高度重现性（+/-0.13 pg）。然而，当在交叉偏振光下具有不对称外观的球石（例如，Helicospheara carteri）没有在特定方向上测量。
The coccolithophores are among the few organisms of the phytoplankton to calcify. Although together with the planktonic foraminifera they dominate calcite production in the open ocean, the amount of calcite they secrete is difficult to deter-mine. The amount of calcite in the form of coccoliths that is dissolved during sedimentation is also difficult to estimate as is the amount of calcite represented by sedimented coccoliths. Because of their minuteness, coccoliths cannot be directly weighed. Instead. indirect methods must be used to estimate their weight.I describe here a method that allows quick estimations of the weight of individual coccoliths. based on the measure of their brightness when viewed in cross-polarized light. This birefringence method can only be applied to the group Heliolithae (excluding some of the coccoliths produced in the Family Coccolithaceae). For Coccolithaceae and some Ortholithae an estimate of the weight can be made using a correcting factor. The birefringence method is highly reproducible (+/- 0.13pg). However, a significant systematic error of 13.5% may occur when coccoliths with asymmetrical appearance in cross polarized light (e.g., Helicospheara carteri) are not measured in specific orientations.