Soil, as a surviving trace after contact and transfer between contacting surfaces at a crime scene, can be recovered and analyzed to infer the presence of persons or tools at the scene and prior activity leading to its deposition. With its vast diversity and heterogeneity, it varies in composition from place to place, providing a basis for trace examiners to distinguish visually similar-colored soils. Unlike countries with native topsoil, Singapore’s urban lands are commonly filled with man-altered and man-transported soil, with relatively little known about the variations of soil’s characteristics within a small, localized area. The current study surveyed the soil’s elemental variability in Singapore parks, which are green spaces for public leisure use. Past installations of recreational facilities and landscaping with fast-growing vegetation in parks inevitably cause disturbance to the original natural soil and mixing with extraneous soil, further contributing to the heterogeneity of the park’s topsoil composition. In our sampling approach, visually similar-colored surface soils were collected from within a 1-m² site, sites in proximity within a park, and parks across Singapore. The collected soils were dried and sieved into clay- and silt-size fractions for elemental analysis using WDXRF and SEM/EDS. To examine the extent of the spatial elemental variability, we adopted three-sigma interval match criteria and a discriminative model incorporating relative data, square root values and the Canberra distance measure for data processing and pairwise comparison of soil samples. The study also aimed to develop soil databases encompassing soils across Singapore with the intent of understanding the value of soil evidence within a local context.

土壤作为犯罪现场接触表面之间接触和转移后残留的痕迹，可以进行回收和分析，以推断现场是否存在人员或工具以及导致其沉积的先前活动。由于其巨大的多样性和异质性，各地的成分各不相同，为痕量检查人员区分视觉上相似颜色的土壤提供了基础。与拥有原生表土的国家不同，新加坡的城市土地通常充满了人工改变和人工搬运的土壤，而人们对小范围局部区域内土壤特性的变化知之甚少。目前的研究调查了新加坡公园的土壤元素变化，这些公园是供公共休闲使用的绿地。以往在公园内设置游乐设施和速生植被景观，不可避免地会对原有的自然土壤造成干扰，并与外来土壤混合，进一步加剧了公园表土成分的异质性。在我们的采样方法中，从 1 米²的场地内、公园内附近的场地以及新加坡各地的公园中收集了视觉上颜色相似的表层土壤。将收集的土壤干燥并筛分为粘土和粉砂尺寸部分，以便使用 WDXRF 和 SEM/EDS 进行元素分析。为了检查空间元素变异的程度，我们采用了三西格玛区间匹配标准和结合相对数据、平方根值和堪培拉距离测量的判别模型来进行数据处理和土壤样本的成对比较。该研究还旨在开发涵盖新加坡各地土壤的土壤数据库，旨在了解当地土壤证据的价值。