(Table 2) Chemical composition of skeletons of scleractinian non-zooxanthelate corals

The first data on chemical composition of nonreef-building non-zooxanthellate deep-sea corals presented in this publication allow us to identify following tendencies manifested in the biomineralization process. Comparison of concentration levels of some chemical elements in scleractinian corals and ambient ocean waters suggests that corals do not accumulate K in the process of biomineralization and weakly accumulate Mg, whereas Ca, Sr, Si, Al, Ti, Mn, Zn, Cu, Cd, Pb, and Fe are concentrated in skeletons of corals with enrichment coefficients of 10**3 to 10**7. Correlations between components contained in the skeletons of scleractinian corals suggest that the source of Al, Si, Fe, and Ti in them is the clayey constituent of bottom sediments and zooplankton, while trace elements are likely accumulated via bioassimilation from seawater. Such elements as Mn, Sr, Pb, and Cd can structurally substitute Ca in calcite and aragonite. Variations in concentrations of the elements in coral skeletons depending on their habitat depths are fairly significant. As could be expected Ca and Mg concentrations are prone to decrease with depth (R = -0.55 and -0.51, respectively), which can possibly be caused by partial dissolution of carbonate skeletons with increasing depth, whereas the Sr/Ca ratio does not depend on depth.

本研究发表的首份非造礁、非虫黄藻共生深海珊瑚的化学成分数据，使我们得以明确其生物矿化过程中呈现的如下规律。通过对比石珊瑚（scleractinian corals）体内部分化学元素与周围海水的浓度水平，可发现珊瑚在生物矿化过程中并未富集钾（K），仅微弱富集镁（Mg）；而钙（Ca）、锶（Sr）、硅（Si）、铝（Al）、钛（Ti）、锰（Mn）、锌（Zn）、铜（Cu）、镉（Cd）、铅（Pb）及铁（Fe）则在珊瑚骨骼中发生富集，富集系数介于10³至10⁷之间。石珊瑚骨骼中各组分间的相关性分析表明，铝、硅、铁及钛的来源为海底沉积物中的黏土组分与浮游动物；而痕量元素则可能通过海水的生物同化作用实现富集。锰、锶、铅及镉这类元素可在方解石与文石晶格中结构替代钙。珊瑚骨骼中元素浓度随栖息深度的变化幅度较为显著。正如预期，钙与镁的浓度随深度增加呈下降趋势（相关系数R分别为-0.55与-0.51），这一现象可能源于碳酸盐骨骼随深度增加发生部分溶解；而锶钙（Sr/Ca）比值则不受深度影响。