Post-mortem oxygen isotope exchange within cultured diatom silica.
Post-mortem oxygen isotope exchange within cultured diatom silica.
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DOI：
10.1002/rcm.7954
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发表时间：
2017-10-30
期刊：
影响因子：
--
通讯作者：
Leng MJ
中科院分区：
文献类型：
--
作者：
Tyler JJ;Sloane HJ;Rickaby REM;Cox EJ;Leng MJ
生物硅氧同位素组成的潜在死后变化对基于沉积硅氧同位素比值（δ 18 O值）的古气候重建的有效性至关重要。我们计算了新鲜培养的硅藻生物硅在实验室加热和储存过程中氧同位素的变化程度。实验使用新鲜培养的硅藻二氧化硅。将二氧化硅样品储存在水中或在20 °C至80 °C的温度下干燥。通过使用δ 18 O值为−6.3至−5.9 ‰和−36.3至−35.0 ‰的端元沃茨进行平行实验，计算了蚀变过程中受影响的氧质量和相关的硅水同位素分馏。通过用BrF 5分步氧化实现脱羟基和随后的氧释放。使用ThermoFinnigan MAT 253同位素比质谱仪测量18 O/16 O比。观察到二氧化硅δ 18 O值的显著变化，最显著的是在40-80 °C下干燥后δ 18 O值的增加。在20 - 80 °C的温度下储存7天也会导致δ 18 O值发生显著变化。质量平衡计算表明，受影响的氧气量与温度呈正相关。蚀变过程中估计的氧同位素分馏是温度的反函数，与高温硅水氧同位素分馏模型的外推一致。通常使用的制备方法可能会显著改变生物硅的δ 18 O值，特别是在处理现代培养或野外收集的材料时。这些过程在自然水生环境中的意义尚不确定;然而，类似的过程也可能影响沉积硅藻，这对解释生物硅承载的δ 18 O古气候记录有影响。
Potential post‐mortem alteration to the oxygen isotope composition of biogenic silica is critical to the validity of palaeoclimate reconstructions based on oxygen isotope ratios (δ18O values) from sedimentary silica. We calculate the degree of oxygen isotope alteration within freshly cultured diatom biogenic silica in response to heating and storing in the laboratory. The experiments used freshly cultured diatom silica. Silica samples were either stored in water or dried at temperatures between 20 °C and 80 °C. The mass of affected oxygen and the associated silica‐water isotope fractionation during alteration were calculated by conducting parallel experiments using endmember waters with δ18O values of −6.3 to −5.9 ‰ and −36.3 to −35.0 ‰. Dehydroxylation and subsequent oxygen liberation were achieved by stepwise fluorination with BrF5. The 18O/16O ratios were measured using a ThermoFinnigan MAT 253 isotope ratio mass spectrometer. Significant alterations in silica δ18O values were observed, most notably an increase in the δ18O values following drying at 40–80 °C. Storage in water for 7 days between 20 and 80 °C also led to significant alteration in δ18O values. Mass balance calculations suggest that the amount of affected oxygen is positively correlated with temperature. The estimated oxygen isotope fractionation during alteration is an inverse function of temperature, consistent with the extrapolation of models for high‐temperature silica‐water oxygen isotope fractionation. Routinely used preparatory methods may impart significant alterations to the δ18O values of biogenic silica, particularly when dealing with modern cultured or field‐collected material. The significance of such processes within natural aquatic environments is uncertain; however, there is potential that similar processes also affect sedimentary diatoms, with implications for the interpretation of biogenic silica‐hosted δ18O palaeoclimate records.
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影响因子：
3.5
作者：
Gendron-Badou, A;Coradin, T;Livage, J
通讯作者：
Livage, J
影响因子：
3
作者：
Koning, E.;Gehlen, M.;Epping, E.
通讯作者：
Epping, E.
DOI：
10.1139/b88-151
发表时间：
1988-06-01
期刊：
CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE
影响因子：
--
作者：
BEAKES, GW;CANTER, HM;JAWORSKI, GHM
通讯作者：
JAWORSKI, GHM
影响因子：
2.3
作者：
Brewer, Tim S.;Leng, Melanie J.;Marsh, Nicholas G.
通讯作者：
Marsh, Nicholas G.
影响因子：
56.9
作者：
CLAYTON, RN
通讯作者：
CLAYTON, RN