Abstract

This study aims to produce a model for the prediction and estimation of unmeasured terrestrial gamma dose rate (TGDR) using statistical analysis based on geological formation and soil type. The measurements of TGDR were conducted in the Pahang state Malaysia, with a total of 640 measured points that covers all geological formations and soil types in the state. The measurements were taken 1 m above the soil surface using Ludlum 19 gamma ray (μR) meter. The measured gamma dose rates ranged from 26 nGy h-1 to 750 nGy h-1 with a mean value of 176 nGy h-1. The data have been normalized to fit a normal distribution. Significance testing was conducted among all geological formations and soil types, using one way analysis of variance (ANOVA). The results indicated strong significant differences due to the different geological formations and soil types present in the State. Pearson Correlation was used to measure the relations between gamma dose rate based on geological formation and soil type (GD,SD) with the gamma dose rate based on geological formation (GD) or gamma dose rate base on soil type (SD). A very good correlation (88.3%) was found between GD,SD and GD or GD,SD and SD. A total of 85 pairs of geological formations and soil types were used to derive the statistical contribution of geological formations and soil types to gamma dose rates. The percentage contribution of the gamma dose rate from geological formation and soil type were found to be 0.580 and 0.311, respectively. The null hypotheses were accepted for 88% of examined data, therefore, the model could be used to predict gamma dose rates based on geological formation and soil type information.