Assessment of Natural Radionuclides, Radiological Hazards, and Heavy Metals in Soils from the Erbil Oil-Production Blocks, Kurdistan Region, Iraq

The Earth’s crust naturally contains radionuclides and toxic trace elements whose concentrations vary with geological formations and geographical conditions, potentially affecting human health despite technological advances. In this study, 20 soil samples were gathered from locations based on oil well positioned and examined for radioactivity and compositional metal analysis using NaI(Tl) and Inductively Coupled Plasma mass spectroscopy (ICP-MS) techniques. The results indicated that the activity concentrations of primordial radionuclides varied significantly. For 226Ra, the values ranged from 6.48 to 47.47 Bq kg−1, with an average of 23.44 Bq kg−1. For 232Th, the concentrations ranged from 0.14 to 13.02 Bq kg−1, yielding an average of 3.72 Bq kg−1. For 40K, the activity concentrations ranged from 200.63 to 628.84, resulting in an average of 385.8 Bq kg−1. Spatial maps of primordial radionuclides are presented and discussed. It was found that 20% of the 226Ra measurements and 25% of the 40K measurements exceeded the corresponding reference values of 32 Bq kg−1 and 420 Bq kg−1, respectively. In contrast, 100% of the 232Th measurements were below the reference value of 45 Bq kg−1. Except for 15% of AGDE, which is out of the range, all calculated hazard indices from primordial radionuclides fall within the internationally recommended values. Potentially toxic trace elements (As, Ba, Be, Cr, Co, and Cu) generally remain below their respective WHO/FAO guideline values. However, in several samples, chromium and iron (100%) exceed the thresholds of 100 ppm and 5000 ppm, respectively. Statistical analysis revealed a strong correlation coefficient of 226Ra with 40K (r = 0.63). In contrast, 226Ra exhibits moderate negative correlations with Be (r = −0.36), Ba (r = −0.31), and Al (r = −0.27). This study provides baseline data for soil radioactive material monitoring, radiological and hazardous metal assessments.