Multivariate Assessment of Natural Radionuclide Distribution and Radiological Risk in Farmland Soils around Mining Communities of Plateau State, Nigeria Using PCA and Cluster Analysis

Abstract

This study evaluates the distribution of natural radionuclides and associated radiological risks in farmland soils surrounding selected mining communities in Plateau State, Nigeria, using an integrated radiological and multivariate statistical approach. Activity concentrations of naturally occurring radionuclides ²³⁸U, ²³²Th, and ⁴⁰K and corresponding radiological hazard indices were obtained through Bismuth Germanate Oxide (BGO) gamma spectrometry. To enhance interpretation of large data, z-score standardization, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) were applied. The results revealed significant spatial variability in radionuclide concentrations and radiological hazards across the study area. PCA identified two dominant principal components explaining over 99% of the total variance. The first component, accounting for the largest proportion of variance, was primarily associated with ⁴⁰K activity and related hazard indices, indicating strong control by geological factors and mining disturbances. The second component reflected contributions from ²³⁸U and ²³²Th, suggesting both lithogenic sources and anthropogenic enhancement. HCA classified the farmland soils into three distinct radiological zones: high, moderate, and low impact areas. The Bisichi farmlands formed a high-risk cluster characterized by elevated radionuclide concentrations, high absorbed dose rates, and hazard indices exceeding recommended safety limits, indicating strong influence from artisanal mining activities and tailings dispersion. Moderate-impact zones showed mixed geogenic and anthropogenic controls, while Kuru and Kassa areas exhibited low radionuclide levels consistent with natural background radiation. The findings highlight potential environmental and public health risks associated with mining activities and background soils thus provides essential baseline information for environmental monitoring and radiological risk mitigation in agricultural regions.