Yan Xiu T, Donaldson Karen M, Davidson Christine M, Gao Yichun, Wu Hanling, Houston Andrew M, Kisdi Aron
Space Mechatronic Systems Technology Laboratory, Department of Design, Manufacture and Engineering Management, University of Strathclyde Glasgow UK
WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde Glasgow UK
RSC Adv. 2018 Oct 31;8(64):36886-36894. doi: 10.1039/c8ra07065b. eCollection 2018 Oct 26.
Field determination of nitrogen in soil is of interest for both terrestrial and Martian applications. Improved management of soil nitrogen levels on Earth could benefit global food production, whilst the determination of soil nitrogen on Mars is required to assess the planet's future habitability. In this study, a mobile laser induced breakdown spectroscopy (LIBS) system with a 1064 nm Nd:YAG laser delivering 25 mJ per pulse was used to assess the effects of sample pretreatment on the measurement of nitrogen in soil. Although pelletisation was preferred, simply milling the sample to <100 mm particle size - which may be more feasible on a remote rover-based analytical platform - improved the spectra obtained. Ablation craters formed in targets prepared from different particle size fractions of the same commercially-available topsoil showed a clear trend in morphology, with smaller particles yielding more uniform craters with fewer fractures. The LIBS emission intensity at 746.83 nm followed a similar trend to results obtained for total nitrogen content in the soil particle size fractions by microanalysis (Perkin Elmer CHN Elemental Analyser) and was well-correlated ( = 0.94) with soil nitrate determined by ion chromatography (Dionex DX-100). Although correlations were less good when analysing field soil samples collected from central Scotland ( = 0.82 for comparison between LIBS and microanalysis) the study nevertheless demonstrates the potential of portable LIBS for measurement of soil nitrogen content.
土壤中氮的现场测定对于地球和火星的应用都具有重要意义。改善地球上土壤氮水平的管理有助于全球粮食生产，而测定火星上的土壤氮对于评估该星球未来的宜居性是必要的。在本研究中，使用了一个配备1064 nm Nd:YAG激光器、每脉冲能量为25 mJ的移动激光诱导击穿光谱（LIBS）系统，来评估样品预处理对土壤中氮测量的影响。尽管压片是首选方法，但简单地将样品研磨至粒径小于100 mm（这在基于漫游车的远程分析平台上可能更可行），也能改善所获得的光谱。由同一种市售表土的不同粒径级分制备的靶材上形成的烧蚀坑在形态上呈现出明显的趋势，较小的颗粒产生的坑更均匀，裂缝更少。746.83 nm处的LIBS发射强度与通过微量分析（珀金埃尔默CHN元素分析仪）获得的土壤粒径级分中总氮含量的结果呈现相似趋势，并且与通过离子色谱法（戴安DX - 100）测定的土壤硝酸盐含量具有良好的相关性（r = 0.94）。尽管在分析从苏格兰中部采集的田间土壤样品时相关性稍差（LIBS与微量分析之间的比较r = 0.82），但该研究仍然证明了便携式LIBS在测量土壤氮含量方面的潜力。
