A method for the analysis of the δ18O of inorganic phosphate extracted from soils with HCl
A method for the analysis of the δ18O of inorganic phosphate extracted from soils with HCl
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DOI：
10.1111/j.1365-2389.2010.01290.x
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发表时间：
2010-12-01
影响因子：
4.2
通讯作者：
Frossard, E.
中科院分区：
文献类型：
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作者：
Tamburini, F.;Bernasconi, S. M.;Frossard, E.
磷酸盐的氧同位素组成 (delta O-18-PO4) 已成功用于研究海水和海洋沉积物中磷 (P) 的生物循环。然而，只有少数研究在土壤中使用了这种方法。为了分析 delta O-18-PO4，必须从土壤中提取磷酸盐，纯化并转化为磷酸银 (Ag3PO4)。已发表的提取方法成功应用于海水和沉积物，当与土壤或富含有机物的样品一起使用时，会导致不纯的 Ag3PO4 沉淀。在这里，我们提出了一种改进的纯化方案，专为土壤和其他富含有机物的样品而设计。用 HCl 萃取后，磷酸盐通过多种矿物质沉淀进行纯化，无需对溶液的 pH 值进行极端调整。我们证明，可以从肥料和具有不同化学和物理特性的各种土壤中生产无污染的 Ag3PO4。我们的第一个同位素结果证实，土壤中磷状态和有效性的差异在 delta O-18-PO4 信号中表达，表明该同位素示踪剂具有了解土壤系统中磷动态的潜力。
The oxygen isotope composition of phosphate (delta O-18-PO4) has successfully been used to study the biological cycling of phosphorus (P) in seawater and marine sediments. However, only a few studies have used this approach in soils. In order to analyse delta O-18-PO4, phosphate must be extracted from the soil, purified and converted to silver phosphate (Ag3PO4). The published extraction methods, successfully applied to marine waters and sediments, lead to the precipitation of impure Ag3PO4 when used with soils or organic-rich samples. Here we present an improved purification protocol, designed for soils and other organic-rich samples. After extraction with HCl, phosphate is purified with multiple mineral precipitations that do not require extreme pH adjustments of the solutions. We show that contaminant-free Ag3PO4 can be produced from fertilizers and various soils with different chemical and physical characteristics. Our first isotopic results confirm that differences in P status and availability in soils are expressed in the delta O-18-PO4 signal, indicating the potential of this isotopic tracer to understand P dynamics in soil systems.