Emission of hydrogen sulfide from sulfur dioxide-fumigated pine trees.

Pine (Pinus silvestris L.) trees subjected to relatively low concentration of SO(2) in the field emit H(2)S from the needles, as demonstrated by gas chromatographic analysis after preconcentration on a molecular sieve. H(2)S is the only reduced sulfurous compound emitted from SO(2) fumigated leaves. The emission is light and SO(2) concentration dependent. Pine trees in the field and in laboratory experiments continue to emit H(2)S several hours after the termination of prolonged SO(2) fumigation. The maximum emission rates observed from pine trees in the field and in laboratory experiments, 14 and 20 nanomoles per milligram chlorophyll per hour respectively, are about the activity expected for the sulfur assimilation pathway in the chloroplasts.