de Caritat Patrice, Woods Brenda, Simpson Timothy, Nichols Christopher, Hoogenboom Lissy, Ilheo Adriana, Aberle Michael G, Hoogewerff Jurian
Australian Federal Police, Canberra, Australian Capital Territory, Australia.
Geoscience Australia, Canberra, Australian Capital Territory, Australia.
J Forensic Sci. 2021 Sep;66(5):1679-1696. doi: 10.1111/1556-4029.14727. Epub 2021 May 6.
Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier transform infrared spectroscopy (FTIR) and magnetic susceptibility (MS), and geochemical data from X-ray fluorescence (XRF; for total major oxides) and inductively coupled plasma-mass spectrometry (ICP-MS; for both total and aqua regia-soluble trace elements) are performed on the survey's 268 topsoil samples (0-5 cm depth; 1 sample per km ). Principal components (PCs) are calculated after imputation of censored data and centered log-ratio transformation. The sequential provenancing approach is underpinned by (i) the preparation of interpolated raster grids of the soil properties (including PCs); (ii) the explicit quantification and propagation of uncertainty; (iii) the intersection of the soil property rasters with the values of the evidentiary sample (± uncertainty); and (iv) the computation of cumulative provenance rasters ("heat maps") for the various analytical techniques. The sequential provenancing method is tested on the North Canberra soil survey with three "blind" samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR and MS (mineralogy), as well as XRF and total ICP-MS (geochemistry) analytical methods, offer the most precise and accurate provenance predictions. Inclusion of PCs in provenancing adds marginally to the performance. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations and gaps, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.
澳大利亚首都直辖区堪培拉北部土壤调查的成分数据被用于开发和测试一种经验性土壤溯源方法。对该调查的268个表层土壤样本（0-5厘米深度；每平方公里1个样本）进行了傅里叶变换红外光谱（FTIR）和磁化率（MS）的矿物学数据，以及X射线荧光（XRF；用于测定总主要氧化物）和电感耦合等离子体质谱（ICP-MS；用于测定总痕量元素和王水可溶性痕量元素）的地球化学数据。在对截尾数据进行插补和中心对数比变换后计算主成分（PCs）。顺序溯源方法的基础是：（i）制备土壤属性（包括主成分）的插值栅格；（ii）明确量化和传播不确定性；（iii）将土壤属性栅格与证据样本的值（±不确定性）相交；（iv）计算各种分析技术的累积溯源栅格（“热图”）。顺序溯源方法在堪培拉北部土壤调查中用三个代表模拟证据样本的“盲”样本进行了测试。精度和准确度的性能指标表明，FTIR和MS（矿物学）以及XRF和总ICP-MS（地球化学）分析方法提供了最精确和准确的溯源预测。在溯源中纳入主成分对性能的提升微乎其微。在土壤溯源中最大化分析物/分析技术的数量是有利的。尽管存在公认的局限性和差距，但得出的结论是，经验性土壤溯源方法可以在法医和情报应用中发挥重要作用。
