Graduate School of Advanced Science and Engineering, Hiroshima University, Higashihiroshima, Hiroshima, Japan.
Research Institute for Humanity and Nature, Kyoto, Japan.
Rapid Commun Mass Spectrom. 2022 Nov 30;36(22):e9393. doi: 10.1002/rcm.9393.
The phosphate oxygen isotope ratio ( ) is a useful technique to trace the sources and biogeochemical cycles of phosphorus (P) in aquatic ecosystems. However, has not been widely used in oligotrophic freshwater systems due to technical and methodological difficulties in collecting sufficient phosphate (PO ) for the analysis, which sometimes requires hundreds of liters of the water sample. In this study, a new approach (PaS-Zir) was developed for the analysis in oligotrophic freshwater systems using zirconium (Zr)-loaded (ZrIRC) resin, which has a high affinity for PO .
ZrClO was added to Amberlite IRC748 to obtain the ZrIRC resin. The adsorption/desorption experiment using KH PO with a known value of was conducted to determine the adsorption/desorption properties of the resin and the likelihood of isotopic fractionation. By installing mesh bags filled with the resin, the PaS-Zir approach was used in two rivers with low PO concentrations (0.2 and 5.3 μmol/L). A conventional sampling method was also performed in the study river with a higher PO concentration to validate the efficacy of the PaS-Zir method.
The adsorption/desorption experiment demonstrated that the ZrIRC resin possessed a sufficient adsorption capacity (153 μmol/resin-mL) and exhibited little isotopic fractionation during the adsorption/desorption processes. Using the PaS-Zir method, we were able to collect sufficient PO samples for the analysis from the rivers within at least 4 days of mesh bag installation. The values (14.2‰ ± 0.2‰) obtained using the PaS-Zir method were comparable to those obtained using the conventional method (14.0‰ ± 0.03‰).
We proved that the PaS-Zir method is applicable to oligotrophic freshwater systems and is generally more efficient than the conventional method. In addition, our method is useful for improving the understanding of the P dynamics of oligotrophic ecosystems because of the extremely low concentration of PO commonly found in them, which are often prone to P pollution.
磷的氧同位素比值（）是一种有用的技术，可以追踪磷在水生生态系统中的来源和生物地球化学循环。然而，由于在贫营养淡水系统中收集足够的磷酸盐（PO）进行分析的技术和方法上的困难，该技术尚未得到广泛应用，有时需要数百升水样。在这项研究中，开发了一种新的方法（PaS-Zir），用于使用负载锆（Zr）的（ZrIRC）树脂在贫营养淡水系统中进行分析，该树脂对 PO 具有高亲和力。
将ZrClO 加入 Amberlite IRC748 中以获得 ZrIRC 树脂。使用具有已知值的 KH PO 进行吸附/解吸实验，以确定树脂的吸附/解吸特性和同位素分馏的可能性。通过安装填充有树脂的网袋，在 PO 浓度较低（0.2 和 5.3 μmol/L）的两条河流中使用 PaS-Zir 方法。在具有较高 PO 浓度的研究河流中也进行了常规采样方法，以验证 PaS-Zir 方法的效果。
吸附/解吸实验表明，ZrIRC 树脂具有足够的吸附容量（153 μmol/树脂-mL），并且在吸附/解吸过程中表现出很少的同位素分馏。使用 PaS-Zir 方法，我们能够在网袋安装后至少 4 天内从河流中收集足够的 PO 样品进行分析。使用 PaS-Zir 方法获得的 值（14.2‰±0.2‰）与使用常规方法获得的值（14.0‰±0.03‰）相当。
我们证明了 PaS-Zir 方法适用于贫营养淡水系统，并且通常比常规方法更有效。此外，由于贫营养生态系统中 PO 的浓度通常非常低，因此经常容易受到 P 污染，因此我们的方法对于改善对贫营养生态系统中 P 动态的理解很有用。
