Emissions and concentrations of hydrogen sulfide in the air of the tropical forest of the Ivory Coast and of temperate regions in France

Atmospheric H 2 S was measured by a fluorometric method (sensitivity 10 ng). In France, for aerated soils the emissions were between 0.8 and 27 μg m −2 h −1 H 2 S (average 5 μg m −2 h −1 ). The soil temperature is an important factor governing this emission. The H 2 S concentrations in the air ranged from 0.017 to 0.17 μg m −3 (average 0.080 μg m −3 ). In the Ivory Coast the H 2 S emissions were estimated between 30 and 300 μg m −2 h −1 . The measured concentrations of H 2 S in the air at ground level ranged from 0.10 to 8.7 μg m −3 . The relative importance of the measured emissions for anoxic soils of the humid equatorial forests in the global S cycle is discussed.