Geochemical Characteristics of Three Hot Springs from Western Thailand

Abstract

At present a total of 118 hot springs are distributed throughout Thailand. Several studies with a focus on high-temperature hot springs related to geothermal resources were conducted in the northern and southern parts of the country. Geochemical data, however; especially isotopes of medium-to-low temperature hot springs are still scarce. Geochemical water analyses and isotope studies can provide crucial information for the future economical development of the hot springs, such as reservoir temperature, water source and quality. This study aims to investigate the chemical composition and stable isotopes (δ18O, δD) of three hot spring waters from western Thailand; Hin Dad, Bor Klueng and Ban Samorthong (surface water temperatures of 40-50 °C). The chemical type of the hot spring waters from Ban Samorthong and Bor Klueng are alkaline-carbonate, while Hin Dad hot spring is a calcium-carbonate type with high amount of sulfate, which is related to bedrock. Based on the silica geothermometer, reservoir temperatures are 65-90 °C. The stable isotopes δ18O and δD of all hot spring waters suggest a recharge with meteoric waters. The three hot springs are well-known for public water recreation and health therapy. Bor Klueng, the least developed of the three hot springs is used by locals as a source of drinking water. Regarding toxic elements, Ban Samorthong hot spring has high fluoride (F-) (14.84 mg L-1); while Hin Dad hot spring shows concentrations of lead (Pb2+) (0.07 mg L-1) and Bor Klueng of Pb2+ (0.02 mg L-1), and F- (4.35 mg L-1) which are above drinking water limits and might lead to health problems. In conclusion, the examination of elemental compositions and stable isotopes (δ18O, δD) of the three hot springs contributes to a better understanding of reservoir temperatures and recharge and can be beneficial for the natural resource development of medium-low temperature hot springs in Thailand.