便携式XRF对西南喀斯特地区碳酸盐岩风化壳土壤分析适用性评估

Applicability of Portable XRF for Analysis of Carbonate Weathered Crust Soils in Karst Regions of Southwest China

应用便携式X射线荧光光谱仪(pXRF)分析了西南喀斯特地区碳酸盐岩风化壳土壤,并与实验室(LAB)分析结果对比,判定了20种元素分析结果的质量等级,探究了检测时长和粒径对精密度的影响,在pXRF中构建了碳酸盐岩风化壳土壤模式,评估了pXRF对该类土壤分析的适用性。主要结果为:1)整体上,pXRF对碳酸盐岩风化壳土壤有较好的分析能力;2)检测时长为120 s时能够兼顾精密度与检测效率;3)粒径从10目减小到200目时,Cu、Nb、Ba、Ce和Th的数据质量等级得到提高,其余15种元素不受影响;4)碳酸盐岩风化壳土壤模式显著提高了pXRF对同类土壤的分析能力,但对碎屑岩和玄武岩的风化壳土壤适用性低。西南喀斯特地区土壤类型丰富,异质性大,单一检测模式难以满足多样化的分析工作,亟需针对特定类型土壤构建检测模式,提高分析精确度,充分发挥pXRF的优越性能,助力西南喀斯特地区土壤地球化学分析工作。同时,本文还为优化pXRF分析能力提供了一种新思路。

A portable X-ray fluorescence spectrometer(pXRF)was applied to analyze carbonate weathered crust soils in the karst region of southwest China.The results were then compared with those obtained via conventional laboratory methods aiming to determine the data quality of the analytical results for 20 elements,and to investigate the effect of detection time and particle size on the analytical precision.We investigated the relationship between the detection time and the particle size as well as its analytical precision.Furthermore,a mode for carbonate weathered crust soils in pXRF was constructed to evaluate the applicability of pXRF in order to analyze the calcareous soils.The main results were that 1)pXRF has a good potential to analyze carbonate weathered crust soils;2)the detection time of 120 s allowed a good balance between precision and efficiency;3)the data quality of Cu,Nb,Ba,Ce and Th was improved when the particle size was reduced from 10 to 200 mesh and the remaining 15 elements were unaffected;4)The carbonate weathered crust soil mode significantly improved the potential of pXRF to analyze calcareous soils,but still has a low applicability to clastic and basalt weathering crust soils.The soils in the karst regions of southwestern China are highly heterogeneous.Thus,it is difficult for a single testing mode to meet the highly diverse analytical tasks.It is therefore urgent to construct detection modes for different types of soils to improve the analytical accuracy and give full play to the superior performance of pXRF,as a result helping soil geochemical analysis in karst regions of southwesten China.Meanwhile,this paper also delivers a new concept for optimizing the analytical applicability of pXRF.