A new sampling method with zirconium‐loaded resin for phosphate oxygen isotope analysis in oligotrophic freshwater systems
A new sampling method with zirconium‐loaded resin for phosphate oxygen isotope analysis in oligotrophic freshwater systems
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一种用于寡营养淡水系统中磷酸盐氧同位素分析的载锆树脂采样新方法
DOI：
10.1002/rcm.9393
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发表时间：
2022
影响因子：
2
通讯作者：
Okuda Noboru
中科院分区：
文献类型：
--
作者：
Ishida Takuya;Tayasu Ichiro;Onodera Shin‐ichi;Ban Syuhei;Okuda Noboru
磷酸盐氧同位素比值（P O）是研究水生态系统中磷（P）的来源和生物地球化学循环的有效方法。然而，由于收集足够的磷酸盐（PO 4）进行分析的技术和方法上的困难，它还没有广泛用于贫营养淡水系统，有时需要数百升的水样。本研究利用对PO 4具有高亲和力的锆（Zr）负载树脂（ZrIRC），建立了一种分析贫营养淡水体系中PO 4的新方法（PaS-Zir）。用KH_2PO_4进行吸附/脱附实验，确定树脂的吸附/脱附性能和同位素分馏的可能性。通过安装充满树脂的网袋，在两条PO 4浓度较低（0.2和5.3 μmol/L）的河流中使用PaS-Zir方法。一个传统的采样方法也进行了研究河流中具有较高的PO 4浓度，以验证的有效性的PaS-Zir method.ResultsThe吸附/解吸实验表明，ZrIRC树脂具有足够的吸附容量（153 μmol/resin-mL），并表现出很少的同位素分馏过程中的吸附/解吸过程。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 4样品进行分析。PaS-Zir法测定结果（14.2‰ ± 0.2‰）与传统方法测定结果（14.0‰ ± 0.03‰）基本一致。此外，我们的方法是有用的，因为贫营养生态系统中常见的极低浓度的PO 4，这往往是容易受到磷污染，提高对磷动力学的理解。
RationaleThe 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 (PO4) for theanalysis, which sometimes requires hundreds of liters of the water sample. In this study, a new approach (PaS‐Zir) was developed for theanalysis in oligotrophic freshwater systems using zirconium (Zr)‐loaded (ZrIRC) resin, which has a high affinity for PO4.MethodsZrClO2was added to Amberlite IRC748 to obtain the ZrIRC resin. The adsorption/desorption experiment using KH2PO4with a known value ofwas 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 PO4concentrations (0.2 and 5.3 μmol/L). A conventional sampling method was also performed in the study river with a higher PO4concentration to validate the efficacy of the PaS‐Zir method.ResultsThe 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 PO4samples for theanalysis from the rivers within at least 4 days of mesh bag installation. Thevalues (14.2‰ ± 0.2‰) obtained using the PaS‐Zir method were comparable to those obtained using the conventional method (14.0‰ ± 0.03‰).ConclusionWe 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 PO4commonly found in them, which are often prone to P pollution.