Study on Behavior of Atmospheric Hydrogen Sulfide by Fluorometric Method

The atomospheric hydrogen sulfide at several ppb levels was determined by fluorometric method. This method is based on the fact that the presence of absorbed H₂S quenches the fluorescence of the FMA (fluorescein mercury (II) acetate) solution. The method shows high sensitivity and reliability, and is suitable for the measurement of H₂S at background levels. The range of determination of H₂S is from- 0.1 to 10 ppb in sampling air volumes of 4l. Hydrogen sulfide is collected by passing the air through two bubblers, each containing 20 ml of 0.1N NaOH. More than 95% of atmospheric H₂S can be collected by passing the air through two bubblers at the rate of 0.2l/min for 20 minutes. In summer 1975, the fluorometric method was used to measure atmospheric H₂S at Hiyoshi, Yokohama. The result of these measurements is shown in Table 1. The average concentration of H₂S during the sampling period was 2.7 ppb (102 measurements). The interesting phenomenon, that the concentration of H₂S decreases during the daytime, was observed (Fig. 2). The concentration of H₂S in the atmosphere, obviously relates to the weather conditions, temperature, humidity, and wind (Figs. 3 and 4). Under retained air conditions, high concentrations of H2S (4 or 5 times higher than the usual values) were measured (Table 3).