Abstract：
Antimony (Sb) isotopic fractionation is frequently used as a proxy for biogeochemical processes in nature. However, to date, little is known about Sb isotope fractionation in biologically driven reactions. In this study, Pseudomonas sp. J1 was selected for Sb isotope fractionation experiments with varying initial Sb concentration gradients (50-200 μM) at pH 7.2 and 30 °C. Compared to the initial Sb(III) reservoir (δ123Sb = 0.03 ± 0.01 ∼ 0.06 ± 0.01‰), lighter isotopes were preferentially oxidized to Sb(V). Relatively constant isotope enrichment factors (ε) of -0.62 ± 0.06 and -0.58 ± 0.02‰ were observed for the initial Sb concentrations ranging between 50 and 200 μM during the first 22 days. Therefore, the Sb concentration has a limited influence on Sb isotope fractionation during Sb(III) oxidation that can be described by a kinetically dominated Rayleigh fractionation model. Due to the decrease in the Sb-oxidation rate by Pseudomonas sp. J1, observed for the initial Sb concentration of 200 μM, Sb isotope fractionation shifted toward isotopic equilibrium after 22 days, with slightly heavy Sb(V) after 68 days. These findings provide the prospect of using Sb isotopes as an environmental tracer in the Sb biogeochemical cycle.
摘要：
锑（Sb）同位素分馏经常被用作自然界中生物地球化学过程的代表。然而,到目前为止,对生物驱动反应中的Sb同位素分馏知之甚少。在这项研究中,假单胞菌。选择J1用于Sb同位素分馏实验，在pH7.2和30°C下具有不同的初始Sb浓度梯度（50-200μM）。与初始Sb（III）储层相比（δ123Sb=0.03±0.01〜0.06±0.01‰），较轻的同位素优先氧化为Sb(V)。在前22天，对于50至200μM的初始Sb浓度，观察到相对恒定的同位素富集系数（ε）为-0.62±0.06和-0.58±0.02‰。因此,Sb浓度对Sb（III）氧化过程中Sb同位素分馏的影响有限，这可以通过动力学主导的瑞利分馏模型来描述。由于假单胞菌sp的Sb氧化速率降低。J1，在初始Sb浓度为200μM时观察到，Sb同位素分馏在22天后移向同位素平衡，68天后，Sb(V)略重。这些发现为在Sb生物地球化学循环中使用Sb同位素作为环境示踪剂提供了前景。
