Substrate properties are pivotal in shaping porewater chemistry and groundwater quality, serving as the primary driving factors. While spatial analysis of geochemical distribution has been extensively explored in hydrochemistry, the application of geostatistical techniques in tropical island soil investigation remains lacking. In this study, we aim to characterise the geochemical and micro-spatial variability of soil along the flow path of groundwater via integration of chemometric and geostatistical techniques. The study was conducted across a ~ 350 m² area of unconsolidated soil profile (2.75 m depth × 125 m length) on a sedimentary island’s aquifer. The results revealed that multivariate statistical analysis coupling iso-factor scores maps can provide key insights to constraint the subsurface geochemical behaviour. Marine and lithogeneous (natural-derived) materials were found to significantly influence the metals distribution across the soil profile. Clay and sesquioxides (Al₂O₃ and Fe₂O₃) from the high-relief area appear to influence the micro-variability of the inland soil, while seawater mixing impacts the subsoil geochemistry. This study concludes that natural sources, pedogenic processes, and seawater intrusion are the major drivers of metals variability in the tropical island aquifer. These findings provided a scientific overview of metals distribution in a seawater–freshwater mixing zone and significant references for the vertical and horizontal distribution of metals in a sandy soil profile. In particular, the chemometric and geostatistical analysis can be potentially used as robust tools for investigating biogeochemical cycling and the source and sink of groundwater pollutants. It is envisaged that future studies could employ a similar approach to explore other islands worldwide.

底质特性对于塑造孔隙水化学和地下水质量至关重要，是主要驱动因素。虽然地球化学分布的空间分析已在水化学领域得到广泛探索，但地统计技术在热带岛屿土壤调查中的应用仍然缺乏。在这项研究中，我们的目标是通过化学计量学和地统计学技术的结合来表征沿着地下水流动路径的土壤的地球化学和微观空间变化。该研究在沉积岛含水层上约 350 m ²的松散土壤剖面区域（2.75 m 深 × 125 m 长）进行。结果表明，结合等因子得分图的多元统计分析可以为约束地下地球化学行为提供关键见解。研究发现海洋和石质（天然来源）材料对土壤剖面上的金属分布有显着影响。高起伏区域的粘土和倍半氧化物（Al ₂ O ₃和Fe ₂ O _{3 ）似乎影响内陆土壤的微观变化，而海水混合则影响底土地球化学。}这项研究的结论是，自然资源、成土过程和海水入侵是热带岛屿含水层金属变异的主要驱动因素。这些研究结果为海水-淡水混合带中金属的分布提供了科学概述，并对沙土剖面中金属的垂直和水平分布具有重要参考意义。特别是，化学计量学和地统计分析可以作为研究生物地球化学循环以及地下水污染物的来源和汇的强大工具。预计未来的研究可以采用类似的方法来探索世界各地的其他岛屿。