Assessment of Annual Effective Radiation Dose from Radon Gas Contamination in Hot Spring Water and Domestic Water in the Khuan Sa Hot Spring Area, Palian District, Trang Province, Southern Thailand

Kanokwan  Inchalaem; Nicharee  Wangkunphom; Arrisa  Juntud; Orranut  Arong; Areeya  Sriraksa; Fajree  Aming; Kotchakorn  Pengsri; Kanokkan Titipornpun

Kanokwan Inchalaem Suratthani Rajabhat University
Nicharee Wangkunphom Suratthani Rajabhat University
Arrisa Juntud Suratthani Rajabhat University
Orranut Arong Suratthani Rajabhat University
Areeya Sriraksa Suratthani Rajabhat University
Fajree Aming Suratthani Rajabhat University
Kotchakorn Pengsri Suratthani Rajabhat University
Kanokkan Titipornpun Suratthani Rajabhat University

Keywords: Radon, annual effective doses, salt hot spring, RAD7-RAD H2O

Abstract

The Khuan Sra Salty Hot Spring, located in Suso Subdistrict, Palian District, Trang Province, was discovered over 100 years ago. Later, it received funding from the Thai Niyom Yangyuen (Sustainable Thai-ism) project for development and expansion, making it available to the public, tourists, and visitors for mineral water soaking therapy. However, this salty hot spring originates from fissures in the Earth's crust, which may allow radon gas to diffuse from the water into the atmosphere, posing potential health risks. This study aimed to examine the physical characteristics and measure radon gas concentrations in the salty hot spring and domestic water (including tap water and groundwater), as well as assess the annual effective radiation dose from ingestion and inhalation. A total of 27 water samples were collected from the salty hot spring and domestic water sources. The results revealed that the average values for temperature, pH, electrical conductivity, total dissolved solids (TDS), salinity, and dissolved oxygen (DO) in the salty hot spring were 42.8±1.42°C, 6.67±0.46, 1.52±0.03 S/m, 8.53±0.18 g/L, 8.84±0.18 ppt, and 8.16±0.53 mg/L, respectively. In contrast, domestic water sources had average values of 27.2±0.67°C, 7.06±0.46, 0.02±0.01 S/m, 0.10±0.06 g/L, 0.10±0.06 ppt, and 7.89±0.20 mg/L, respectively. The average radon concentration in both the salty hot spring and domestic water was 33.48±10.11 Bq/L, exceeding the standard limit for radon contamination in drinking water (11.1 Bq/L). However, when estimating radon diffusion from the water into the atmosphere, the average concentration was 3.35±1.01 Bq/m³, which is below the global outdoor average (15 Bq/m³). Additionally, the estimated average annual radiation dose was 92.88±6.95 µSv/y, within the reference level (100 µSv/y), while the background radiation level was 1.50±0.19 mSv/y.