Radon ( 222 Rn) Exhalation and Soil Geochemistry in Miocene Sediments Near the Mat Fault, Mizoram, India

Abstract

Radon-222 in soil reflects radionuclide availability and transport through pore space. We compare soil texture, bulk X-ray fluorescence (XRF) composition and 15 reported radon mass-exhalation rates from three stations in Miocene Surma Group sediments near the Mat Fault, Mizoram, India. Each location contributes five rates. Mean ± sample standard deviation is 0.02907 ± 0.00728 Bq kg⁻¹ h⁻¹ at L1, 0.02212 ± 0.00142Bq kg⁻¹ h⁻¹ at L2 and 0.02913 ± 0.00989 Bq kg⁻¹ h⁻¹ at L3. The L1 and L3 means are similar, whereas L2 is lower in this set; measurement dates and sample moisture states are not supplied, so the differences cannot be attributed to station geology or season. L3 has the largest measured P (0.377%), Zr (0.0709%) and K (3.24%), yet a three-site comparison cannot establish a geochemical association with exhalation. Soil-gas concentration at depth is distinguished from laboratory mass exhalation. These observations motivate replicated, paired radionuclide, mineralogical and transport-property measurements before source or fault effects are inferred.