Distribution, Enrichment and Principal Component Analysis for Possible Sources of Naturally Occurring and Anthropogenic Radionuclides in the Agricultural Soil of Punjab State, India

Enrichment factor (EF) of elements including geo-accumulation indices for soil quality and principal component analysis (PCA) were used to identify the contributions of the origin of sources in the studied area. Results of 40K, 137Cs, 238U and 232Th including their decay series isotopes in the agricultural soil of Mansa and Bathinda districts in the state of Punjab were presented and discussed. The measured mean radioactivity concentrations for 238U, 232Th and 40K in the agricultural soil of the studied area differed from nationwide average crustal abundances by 51, 17 and 43 %, respectively. The sequence of the EFs of radionuclides in soil from the greatest to the least was found to be 238U > 40K > 226Ra > 137Cs > 232Th > 228Ra. Even though the enrichment of naturally occurring radionuclides was found to be higher, they remained to be in Igeo class of ‘0’, indicating that the soil is uncontaminated with respect to these radionuclides. Among non-metals, N showed the highest EF and belonged to Igeo class of ‘2’, indicating that soil is moderately contaminated due to intrusion of fertiliser. The resulting data set of elemental contents in soil was also interpreted by PCA, which facilitates identification of the different groups of correlated elements. The levels of the 40K, 238U and 232Th radionuclides showed a significant positive correlation with each other, suggesting a similar origin of their geochemical sources and identical behaviour during transport in the soil system.