Multivariate statistical study of technologically enhanced naturally occurring radioactive materials and radiation hazards in crude oil and petroleum products of Ma’rib refinery, Yemen

Abstract

Crude oil and oil products are among the significant sources of technologically enhanced naturally occurring radioactive materials (TENORMs). Thirty-one samples of eight types of crude oil and petroleum products were collected from the Ma’rib Refinery, located in the Ma’rib Governorate, central Yemen. These samples were analyzed using a gamma-ray spectroscopy system with a high purity germanium detector (HPGe). The specific radio-activities of 40K, 232Th, and 226Ra for crude oil samples ranged 5.943–32.252, 1.711–12.646, and 2.445–15.520 Bq L−1, respectively. Oil products ranged 8.333–40.355, 1.556–12.812, and 3.014–17.024 Bq L−1. Potential environmental and health risks were assessed by calculating radiation hazard indicators of radium equivalent activity (Raeq) Bq L−1, absorbed gamma dose rate (AGDR) nGy h−1, annual effective dose rate (AEDR) mSv, external hazard index (Hex), internal hazard index (Hin), annual gonadal dose equivalent (AGDE) mSv, activity utilization index (AUI), excess lifetime cancer risk (ELCR), activity concentration index (Iy), and alpha index (Iα) that ranged 5.614–33.291, 2.636–15.589, 0.003–0.019, 0.016–0.093, 0.022–0.135, 0.018–0.106, 0.045–0.285, 0.011–0.067, 0.041–0.239, and 0.012–0.078 for crude oil and 9.453–36.067, 4.475–16.837, 0.005–0.021, 0.026–0.101, 0.037–0.147, 0.031–0.114, 0.019–0.072, 0.076–0.314, 0.069–0.258, and 0.015–0.085 for oil products. The estimated average values of these indicators were compared with global averages and were below the recommended limits. The relationship between TENORMs and radiation hazard indicators and their maximum activity contributions were determined by applying multivariate statistical methods. This study is important to provide an overview of activity concentrations of natural radionuclides in the petroleum industry of Yemen. Therefore, the results are useful for assessing the radiological hazards of petroleum products in humans.