Operations and Principles of Low Level Liquid Scintillation counters and application in Water Resource Managemen : Summer Internship Training Report

Abstract

Tritium (^3H), a radioactive isotope of hydrogen with a half-life of 12.32 years, serves as a vital tracer for determining the age and recharge characteristics of groundwater. Naturally produced through cosmic ray interactions and historically elevated by mid-20th century nuclear testing, tritium integrates into the hydrological cycle primarily as tritiated water (HTO). This applies tritium dating to groundwater samples from eight locations in Punjab, India, using measured tritium units (TU) and liquid scintillation counting (LSC) to infer residence times. Groundwater samples underwent pre-treatment, electrolytic enrichment, and final tritium activity measurement using an ultra-low-level liquid scintillation spectrometer. Tritium concentrations were converted to TU, and water ages were estimated using the radioactive decay formula, assuming a modern recharge level of 10 TU. The results reveal a spatial gradient in groundwater age. This regional tritium distribution suggests groundwater flow from northwest to southeast and highlights variations in recharge conditions driven by topography, aquifer type, and anthropogenic influences. This report also explains the utility of tritium as a tracer for delineating recharge zones, estimating flow velocities, and guiding sustainable groundwater management. Future integration of stable isotope analysis (δ¹⁸O, δ²H) and hydrogeological modeling is recommended to enhance understanding of recharge sources and aquifer connectivity.