基于便携式X射线荧光光谱法的深海沉积物现场成分快速检测及适用性评估

    Rapid in-situ assaying of deep-sea sediments by portable X-ray fluorescence spectrometry and its applicability assessment

    • 摘要: 远洋粘土、硅藻软泥、铁锰结核及结壳是常见的深海沉积成因物质类型,在开展深海地质调查工作时及时获得这些物质的成分信息,对于提升海上地质调查效率和认知能力十分重要。通过便携式X射线荧光光谱法(pXRF)对菲律宾海深水区域60个样品进行分析,并结合实验室测试结果,评估pXRF能测出的24种元素含量数据的稳定性、准确性及相关性,探讨pXRF在海上地质调查工作中对于深海沉积物现场成分快速检测的适用性。通过综合对比研究发现,Ca、Cu、Fe、K、P、Pb、Sr、Zn、Zr九种元素稳定性、准确性和相关性较好,可以直接用于定性乃至定量研究工作。Al、Ba、Mn、Mo、Ni、Rb、Si、Ti、Th、V十种元素的三项指标参数等级略低,可用于含量高低判定和趋势分析等定性研究工作。Bi、Cs、Mg、Sb、Sc五种元素的测试效果较差,本法不建议使用。取样量充足且分布均匀、湿样烘干至恒量后研磨过筛、封装时充分压实平整、测试时间增长、选择合适的标准物质校正和检验、重点和异常样品增加测试次数等措施的执行有利于获得高精度的pXRF海上测试数据。未来对更多类型和数量深海样品开展pXRF现场分析,将有利于建立更精准的测试方法流程,达到现场快速揭示样品成分特征、确定底质类型及圈定矿化异常等目的,为海上关键决策的部署和实施提供参考和借鉴。

       

      Abstract: The pelagic clay, diatom ooze, ferromanganese nodules and crusts covering a large area of the abyssal plains are the common types of deep-sea sediments.It is very important to detect the composition of these sediments timely and accurately for improving the efficiency and cognitive ability of marine geological survey.Based on the assay of 60 samples collected from Philippine Sea by portable X-ray fluorescence spectrometry (pXRF), combined with laboratory test results, three key parameters of stability, accuracy and correlation of 24 elements detected, and its applicability of rapid detecting of deep-sea sediments to marine geological survey was discussed.Through comprehensive comparative study, it is found that nine elements, Ca, Cu, Fe, K, P, Pb, Sr, Zn and Zr, have good stability, accuracy and correlation, and can be directly used in qualitative and even quantitative research.The three index parameters of Al, Ba, Mn, Mo, Ni, Rb, Si, Ti, Th and V are slightly lower, which can be used for qualitative research and trend analysis.The elements of Bi, Cs, Mg, Sb and Sc are not recommended to use because of their poorly testing results.The measures beneficial to acquire high precision test data include adequate and uniform sampling volume, grinding and screening after drying to a constant of wet samples, adequate compaction and flattening during packaging, increasing test time, selecting appropriate reference materials for calibration and inspection, and increasing test times for key and abnormal samples.With the increase of the type and number of deep sea samples in the future, the pXRF method will be conducive to the establishment of more accurate test methods, so as to quickly reveal the composition characteristics of samples in the field and delineate mineralization anomalies etc.In this way, it can be used as a reference for the decision-making and deployment of key offshore projects.

       

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