Investigation of radioactivity and heavy metal levels in soil samples from neutral and vegetation land of Punjab, India

In this work, radioactivity investigations of soil samples from neutral and agricultural sites in Punjab (India) have been carried out to study the impact of land use patterns. Analyzing soil samples radiological, mineralogical, and physicochemical attributes has employed state-of-the-art techniques. The mean activity concentration of ²³⁸U/²²⁶Ra, ²³²Th, ⁴⁰K, ²³⁵U, and ¹³⁷Cs, measured using a carbon fiber endcap p-type HPGe detector, in neutral land was observed as 58.03, 83.95, 445.18, 2.83, and 1.16 Bq kg⁻¹, respectively. However, in vegetation land, it was found to be 40.07, 64.68, 596.74, 2.26, and 1.90 Bq kg⁻¹, respectively. In the detailed activity analysis, radium equivalent (Ra_eq) radioactivity is in the safe prescribed limit of 370 Bq kg⁻¹ for all investigated soil samples. However, the dosimetric investigations revealed that the outdoor absorbed gamma dose rate (96.08 nGy h⁻¹) and consequent annual effective dose rate (0.12 mSv y⁻¹) for neutral land and the gamma dose rate (82.46 nGy h⁻¹) and subsequent annual effective dose rate (0.10 mSv y⁻¹) for vegetation land marginally exceeded the global average. The soil’s physicochemical parameters (pH, EC, and porosity) from both sites were measured, and their correlations with radionuclides were analyzed. Various heavy metals of health concern, namely, chromium (Cr), arsenic (As), copper (Cu), cobalt (Co), cadmium (Cd), lead (Pb), mercury (Hg), selenium (Se), and zinc (Zn), were also evaluated in soil samples using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). Pollution Load Index (PLI) and Ecological Risk Index (RI) revealed that vegetation land was more anthropogenically contaminated than neutral land, with maximum contamination from Hg and As.