Method for analyzing the oxygen isotope composition of HCl-extractable inorganic phosphate in sediments and soils. (July 2021)

• Record Type: Journal Article
• Authors: Liu, Yong; Wang, Jingfu; Yang, Haiquan; Jiang, Shihao; Jin, Zuxue; Chen, Jingan
• Is Part Of: Applied geochemistry. Volume 130(2021)
• Publication Date: 2021-07
• Subjects: Method -- Phosphate oxygen isotope -- HCl-PTI -- Zr-oxide gel -- Sediments -- Soils; Environmental geochemistry -- Periodicals; Water chemistry -- Periodicals; Geochemistry -- Social aspects -- Periodicals; Geochemistry -- Periodicals; 551.9
• DOI: 10.1016/j.apgeochem.2021.104978
• Languages: English
• ISSNs: 0883-2927

Abstract

Abstract: The oxygen isotope ratio in phosphate (δ 18 OP ) is an effective tool for tracing the sources of phosphorus (P) and their biogeochemical cycles. The HCl-extractable inorganic phosphate (HCl-PTI ) is the primary component of P and plays a key role in the dynamic transformation of P in sediment and soil. However, it has always been difficult to purity sample for analyzing the δ 18 OP composition of HCl-PTI due to the significantly interference of large amounts of Fe 2+/3+, Ca 2+, Cl − and other impurities in the HCl-PTI extracts. In this study, we developed a simple and promising purification method for δ 18 OP analysis of HCl-PTI in sediments and soils based on the superior selective enrichment and elution abilities of phosphate (PO4 ) and efficient synchronous removal of impurities by Zr-Oxide gel in highly acidic HCl-PTI extract. The enrichment rate and elution rate of PO4 in the HCl-PTI extract by the Zr-Oxide gel could achieve 100% respectively, and the synchronous removal rates of most anions, dissolved organic carbon (DOC), metals, and trace elements could be above 96% respectively, reducing the tedious operation of conventional methods and the difficulties in removal of impurities, such as Cl − in HCl-PTI extract. It's indicated that the purity of the Ag3 PO4 solid for δ 18 OP composition analysis of HCl-PTI could reach 99.9%. The above results show that the new method is very simple, efficient and reliable for the δ 18 OP analysis of HCl-PTI in sediments and soils. This study provides new methodological support for identifying the sources of P and tracing their biogeochemical cycles in sediment or soil environment. Graphical abstract: Image 1 Highlights: A method based on selective enrichment and elution of PO4 in HCl-PTI extracts. It avoids the significant interference of Fe 2+/3+, Ca 2+, Cl − and other impurities. A simple purification protocol for HCl-PTI δ 18 OP analysis in sediments and soils. A new methodological tool to trace the P source and its biogeochemical cycle.