Zhang Hailin, Antonangelo João, Penn Chad
Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK, 74078, USA.
U.S. Department of Agriculture, National Soil Erosion Research, West Lafayette, IN, 479072077, USA.
Sci Rep. 2021 Feb 16;11(1):3901. doi: 10.1038/s41598-021-83584-4.
Portable X-ray fluorescence (pXRF) spectrometer allows fast in-situ elemental determination without wet digestion for soils or geological materials, but the use of XRF on wet materials is not well documented. Our objective was to develop a rapid field method using pXRF to measure metals in the residues from horizontal directional drilling (HDD) operations so that proper disposal decisions can be made in-situ. To establish the procedure, we spiked soil samples with 4 concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb up to 1000 mg kg, and then the metal concentrations were determined by wet chemical method after drying and acid digestion (standard method), and by pXRF, also at laboratory conditions, after drying and at two different moisture conditions. The measurements by pXRF and standard method after drying and after removal of excess water (AREW) were highly correlated with slopes ranging from 0.83 ± 0.01 to 1.08 ± 0.01 (P < 0.001) for all metals. The relationship was better AREW than the saturated paste without removal of excess water and the moisture content affected only the accuracy of As, Cd, and Pb. The procedure established was successfully used for HDD residues collected from 26 states of US with moisture content ranging from 14 to 83% AREW. The pXRF was proven to be a reliable tool for fast detection of common metals in dried soils and HDD residues, and samples containing < 30% moisture content without needing to correct for moisture. If the moisture is > 30%, excess water in samples need to be removed with a commercially available filter press to achieve high accuracy. The developed procedures reduce time of metal detection from days to about an hour which allows drilling operators to make quick decisions on soil or HDD disposal.
便携式X射线荧光（pXRF）光谱仪能够在不进行湿法消解的情况下，对土壤或地质材料进行快速原位元素测定，但XRF在潮湿材料上的应用记录并不充分。我们的目标是开发一种快速现场方法，使用pXRF测量水平定向钻进（HDD）作业产生的残渣中的金属含量，以便能够在现场做出合适的处置决策。为了建立该程序，我们在土壤样品中加入了4种浓度的铬、镍、铜、锌、砷、镉和铅，最高浓度达1000 mg/kg，然后在干燥和酸消解后通过湿化学方法（标准方法）测定金属浓度，并在实验室条件下，在干燥后以及两种不同湿度条件下通过pXRF进行测定。对于所有金属，干燥后以及去除多余水分（AREW）后通过pXRF和标准方法进行的测量具有高度相关性，斜率范围为0.83±0.01至1.08±0.01（P<0.001）。去除多余水分后的关系比未去除多余水分的饱和糊剂更好，且水分含量仅影响砷、镉和铅的准确性。所建立的程序成功应用于从美国26个州收集的HDD残渣，其水分含量范围为14%至83% AREW。事实证明，pXRF是一种可靠的工具，可用于快速检测干燥土壤和HDD残渣中的常见金属，以及水分含量低于30%的样品，无需对水分进行校正。如果水分含量大于30%，则需要使用市售压滤机去除样品中的多余水分，以实现高精度。所开发的程序将金属检测时间从数天缩短至约1小时，这使钻探操作人员能够对土壤或HDD处置做出快速决策。
