Trace elements and radioactivity measurements in some terrestrial food crops in Jos-plateau, north central, Nigeria

Abstract

Some crops of important nutritive requirements have been collected from farmlands located in Bitsichi an old tin mining town in north central region of Nigeria. The food crops were analyzed in order to determine trace element concentrations level using Neutron Activation Analysis (NAA). The activity concentrations due to natural radionuclides in the food samples and soil samples collected within the root zone of the crops were also determined using gamma-ray spectrometry (GRS). The NAA results obtained showed higher concentration of Potassium among the essential elements in all the crops. Calcium concentration in both maize and Guinea corn was below detection limit and also Zn in Green beans, sweet potato and cassava. The trace elements; Sc, Hf, Sm, and Th, were below detection limit in all the crops except in Green beans. Rubidium (Rb) and lanthanum (La) were below detection limits only in Cabbage. The activity concentrations of the natural radionuclides in the food samples were found to vary between 83 and 129 Bq kg -1 for 40 K, 19 and 30 Bq kg -1 for 226 Ra and 27 to 41 Bq kg -1 for 232 Th. In the soil samples the activity concentrations varied between 177 and 271 Bq kg -1 for 40 K, 53 and 96 Bq kg -1 for 226 Ra and 73 to 176 Bq kg -1 for 232 Th. Results of activity concentration levels of the radionuclides obtained in similar crops collected for control measurements were found to be very low compared to those from the study area. The effective dose due to intake of the food crops considered in the study area was estimated based on the measured activity concentrations of 226 Ra and 232 Th in the food crops. It was found to vary between 0.01 mSv y -1 (Acha) and 1.35 mSv y -1 (Cassava) with a cumulative total dose estimated as 2.5 mSv y -1 . The mining activities in the area are seen to have influenced the concentration of these trace elements and radionuclides in the food crops. However, they are seen not to pose any serious internal health burden due to ingestion given the realities of food choice by individuals in the study area.