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引用本文:薛珂,张润宇,安宁,陈敬安,邹银洪,刘勇,张志.淡水磷酸盐氧同位素前处理方法的优化.湖泊科学,2021,33(1):319-326. DOI:10.18307/2021.0127
Xue Ke,Zhang Runyu,An Ning,Chen Jing'an,Zou Yinhong,Liu Yong,Zhang Zhi.Optimization approach of pretreatment methods for phosphate oxygen isotopic analysis in freshwater. J. Lake Sci.2021,33(1):319-326. DOI:10.18307/2021.0127
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淡水磷酸盐氧同位素前处理方法的优化
薛珂1,2, 张润宇1, 安宁1, 陈敬安1, 邹银洪1, 刘勇1,2, 张志1,2
1.中国科学院地球化学研究所, 贵阳 550081;2.中国科学院大学, 北京 100049
摘要:
磷是地表水体中的关键性营养盐,在水生生态系统的物质循环与能量流动方面发挥着重要作用,研究水体中磷的来源、转化与归趋对于了解水环境的演变过程与科学保护具有重要意义.近年来,磷酸盐氧同位素(δ18OP)技术已逐渐应用于淡水环境中磷的来源示踪与生物地球化学循环研究,其样品前处理主要沿用海水方法体系.相比而言,淡水样品中PO43-浓度通常较低,有机质和干扰离子含量却较高,复杂的样品前处理过程极大地制约了δ18OP分析在淡水环境体系的广泛应用.为此,本研究针对现有海水样品δ18OP前处理方法在地表淡水环境的适用性加以检验,并进行了三点优化改进:①将MAGIC沉淀步骤使用的MgCl2替换为Mg(NO32,避免了Cl-的干扰,减少AgCl杂质的生成;②调节生成Ag3PO4溶液pH值为8.0,保证Ag3PO4沉淀快速完全;③对Ag3PO4沉淀过程采用避光处理,降低了AgNO3及Ag3PO4可能的光解影响,提高了Ag3PO4的纯度,使δ18OP的测试结果更为准确.本改进方法为后续利用δ18OP技术深入探究淡水环境中磷的生物地球化学循环与生态环境效应提供了有益的方法借鉴.
关键词:  淡水环境    磷酸盐氧同位素  前处理方法  改进
DOI:10.18307/2021.0127
分类号:
基金项目:国家自然科学基金项目(41573133,41273151)和国家自然科学基金委员会-贵州喀斯特科学研究中心项目(U1612442)联合资助.
Optimization approach of pretreatment methods for phosphate oxygen isotopic analysis in freshwater
Xue Ke1,2, Zhang Runyu1, An Ning1, Chen Jing'an1, Zou Yinhong1, Liu Yong1,2, Zhang Zhi1,2
1.Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China;2.University of Chinese Academy of Sciences, Beijing 100049, P. R. China
Abstract:
Phosphorus (P) is one of the key nutrients in surface water, and plays a vital role in the material cycle and energy flow in aquatic ecosystems. Hence, it is of great significance to explore the source, transformation, and fate in water body for understanding its evolution process and scientific protection of water environment. Recently, phosphate oxygen isotope technology (δ18OP) has been gradually applied in tracing the P source and studying the biogeochemical cycle in freshwater environment, which most used the sample pretreatment of seawater methods. By contrast, the concentrations of PO43- in freshwater samples are usually low, whereas the contents of organic matter and interference ions are high. The pretreatment complexity restricted the extensive application of δ18OP analysis in freshwater ecosystems. This study examined the applicability of the existing pretreatment methods of seawater sample in surface freshwater environment, and further carried out three optimization improvements: ①We replaced MgCl2 solution with Mg(NO3)2 solution in the MAGIC precipitation step to avoid the interference of Cl- and the impurities of AgCl. ②The solution pH value of Ag3PO4 precipitation was adjusted to 8.0 to ensure the rapid and complete precipitation. ③Possible photolysis effects of AgNO3 and Ag3PO4 were inhibited by using light avoidance. This modification improved the purity of Ag3PO4, and attained more accurate δ18OP results. The present method gives a valuable reference to further study of the biogeochemical cycle and eco-effects of P in freshwater environment using δ18OP analysis.
Key words:  Freshwater environment  phosphorus  phosphate oxygen isotope  pretreatment method  improvement
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