Spatial distribution and health impact assessment of radionuclides and trace metals in soils of Delta Central, Nigeria.

Abstract

The environment is currently exposed to radiation contamination from both natural and human-made sources, as well as to metal contamination resulting from industrial and agricultural activities such as oil and gas exploration and export, alongside large-scale mechanized farming, especially in the Delta Central region. This study aimed to assess the impact of these human and natural processes on Delta Central soil by measuring the activity levels of radionuclides (²³⁸U, ²³²Th, ⁴⁰K) and trace metals (Cu, Zn, Mn, Pb), and by evaluating the health risks associated with these elements. Eighteen locations within Delta Central were sampled to obtain uniform soil samples from a depth of 0 to 10 cm. The samples were analyzed using a sodium iodide detector spectrometry system and an atomic absorption spectrometry system. The activity concentration levels for ²³⁸U ranged from 7.16 Bq/kg to 10.96 Bq/kg, for ²³²Th from 2.97 Bq/kg to 5.49 Bq/kg, for ⁴⁰K from 226.82 Bq/kg to 262.13 Bq/kg, for Cu from 0.005 mg/kg to 0.108 mg/kg, for Zn from 0.058 mg/kg to 2.533 mg/kg, for Mn from 0.125 mg/kg to 2.115 mg/kg, and for Pb from 1.805 mg/kg to 4.183 mg/kg. The present study revealed that Delta Central current activity concentration level for the investigated radionuclides and trace metals is lower than the world permissible limit, with no immediate concern for high concentration alert. However, frequent monitoring of Delta Central is required, and an expanded study on more radionuclides and metals exposure within residential and agricultural lands in Delta Central is recommended.