Controls on stable strontium isotope fractionation in coccolithophores with implications for the marine Sr cycle
Controls on stable strontium isotope fractionation in coccolithophores with implications for the marine Sr cycle
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DOI：
10.1016/j.gca.2013.11.043
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发表时间：
2014-03
影响因子：
5
通讯作者：
E. Stevenson;M. Hermoso;R. Rickaby;J. Tyler;F. Minoletti;I. Parkinson;F. Mokadem;K. Burton
中科院分区：
文献类型：
--
作者：
E. Stevenson;M. Hermoso;R. Rickaby;J. Tyler;F. Minoletti;I. Parkinson;F. Mokadem;K. Burton
球石藻（emiliania huxleyi, cocolithus pelagicusspp.）产生的方解石中稳定Sr同位素分选的控制。研究了海苔属和海苔属植物。每个物种都在受控的实验室条件下，在10-25°C的温度范围内进行培养，以测试δ88/86Sr作为生长速度和/或海面温度的代表的潜力。球石藻是最丰富的远洋钙化生物之一；由于锶在其方解石球粒岩中一定程度上替代了Ca，因此球粒岩代表了来自海水的大量锶输出，可能影响现代海洋的δ88/86Sr质量平衡。测定了其δ88/86Sr、Sr/Ca和δ18O随温度的变化。随着温度的升高，所有物种都表现出负稳定的Sr同位素分馏，这与温度控制的生长速率有关。我们推断δ88/86Sr向较轻值的转移表明了对同位素分馏的动力学控制，揭示了δ88/86Sr作为生长速率的代表的潜力，在这些实验中，生长速率主要由温度决定。结果表明，球石方解石中含锶，δ88/86Sr同位素组成极轻，低至~ 0‰。
The controls on stable Sr isotope fractionation into the calcite produced by the coccolithophore speciesEmiliania huxleyi,Coccolithus pelagicusspp.braarudiiandGephyrocapsa oceanicaare investigated.Each species has been cultured under controlled laboratory conditions at a range of temperatures (10–25 °C) to test the potential of δ88/86Sr as a proxy for growth rate and/or sea surface temperature. Coccolithophores are one of the most abundant pelagic calcifiers; since Sr substitutes to some degree for Ca in their calcite coccoliths, coccolithophores represent a significant output of Sr from seawater, potentially influencing the δ88/86Sr mass balance in the modern oceans. The coccoliths are investigated for their δ88/86Sr, Sr/Ca, and δ18O measured as function of temperature. As temperature is increased all species show a negative stable Sr isotopic fractionation, related to a temperature controlled growth rate. We infer the shift of δ88/86Sr to lighter values as indicative of a kinetic control on the isotope fractionation, revealing the potential of δ88/86Sr as a proxy for growth rate, which in these experiments is primarily dictated by temperature. The results from these experiments indicate that coccolithophore calcite incorporates Sr with a very light δ88/86Sr isotope composition as low as ∼0‰.