Preliminary Study of Iron-Rich Precipitates of Huanggang Hot Spring, Jinshan District, northern Taiwan

A new hot spring well was excavated in 2017 at a public bath facility at the Huanggang hot spring in Jinshan District, New Taipei City, northern Taiwan. The new hot spring water was characterized as an iron-rich chloride-sulfate spring (pH 5.6) which forms yellowish precipitates along its flow path. X-ray diffraction and electron microscopic analytical results showed that the main mineral phase of the precipitates was 2-line ferrihydrite, which forms aggregates of submicron spheroids and is rich in silicon. No obvious phase transition of ferrihydrite during aging was observed, which can be attributed to the co-precipitation with silicon. The metal adsorption mechanism and phase transformation behavior of ferrihydrite, as well as their influence on the migration of toxic substances in hot spring water, are worthy of further investigation.