Precise calibration of equilibrium oxygen isotope fractionations between dissolved phosphate and water from 3 to 37 °C
Precise calibration of equilibrium oxygen isotope fractionations between dissolved phosphate and water from 3 to 37 °C
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DOI：
10.1016/j.gca.2014.10.030
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发表时间：
2015-02-01
影响因子：
5
通讯作者：
Blake, Ruth E.
中科院分区：
文献类型：
--
作者：
Chang, Sae Jung;Blake, Ruth E.
正磷酸盐的稳定氧同位素组成（δ O-18（PO 4））是一种广泛使用的（古）温度指示剂，最近，磷循环的有用示踪剂。在天然含水系统中（例如，海洋、河流、土壤/地下水）中最大的活性磷库是溶解的无机磷酸盐。在这里，我们提出了一个新的实验确定的方程的热力学平衡O-同位素分馏溶解磷酸盐和水，催化的酶无机焦磷酸酶（PPase）之间的3和37摄氏度; 1000 ln alpha（（PO4-H2O））= 14.43（+/- 0.39）1000/T（K）- 26.54（+/- 1.33）r（2）= 0.99新方程与最近基于生物磷灰石的实验测定的分馏略有偏移，偏移量为+0.5至+0.7 ‰，两者均基于Ag 3 PO 4的现代cf-irms TC/EA分析。溶解的磷酸盐-水的分馏被抵消了+0.9至+2.3千分之一，从早期的经验关系，生物源磷酸盐-水分馏使用BiPO 4的双磷酸盐测定。因此，这里提出的方程是特定的溶解磷酸盐和水之间的平衡分数，并适用于最近/未来的溶解磷酸盐的氧同位素研究使用类似的cf-irms TC/EA分析方法。(C)2014爱思唯尔有限公司版权所有。
The stable oxygen isotope composition of orthophosphate (delta O-18(PO4)) is a widely used (paleo) temperature indicator and more recently, a useful tracer of phosphorus-cycling. In natural aqueous systems (e.g., oceans, rivers, soil/ground water) the largest reactive phosphorus pool is dissolved inorganic phosphate. Here, we present a new experimentally-determined equation for thermodynamic equilibrium O-isotope fractionations between dissolved phosphate and water, catalyzed by the enzyme inorganic pyrophosphatase (PPase) between 3 and 37 degrees C;1000 ln alpha((PO4-H2O)) = 14.43(+/- 0.39) 1000/T (K) - 26.54(+/- 1.33) r(2) = 0.99The new equation is slightly offset by +0.5 to +0.7 parts per thousand from recent empirically-determined fractionations based on biogenic apatite, with both based on modern cf-irms TC/EA analysis of Ag3PO4. Dissolved phosphate-water fractionations are offset by +0.9 to +2.3 parts per thousand from the earlier empirical relation for biogenic phosphate-water fractionation determined using fluorination of BiPO4. The equation presented here is thus, specific to equilibrium fractions between dissolved phosphate and water and appropriate for use in recent/future oxygen isotope studies of dissolved phosphate using similar cf-irms TC/EA analytical methods. (C) 2014 Elsevier Ltd. All rights reserved.