Is emission of hydrogen sulfide a dominant factor of SO2 detoxification? A comparison of Norway spruce (Picea abies (L) Karst), Scots pine (Pinus sylvestris L) and Blue spruce (Picea pungens Engelm) in the Ore mountains

The emission of reduced volatile sulfur compounds from Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and Blue spruce (Picea pungens Engelm.) growing at high elevation in the Ore mountains (Kahleberg, Germany, altitude 907 m) was measured in the field by cryosampling and gaschromatographic analysis. Twigs still attached to the trees were enclosed in a flow-through gas exchange cuvette and H2S was detected as the predominant reduced sulfur compound in the effluent gas stream. Carbonylsulfide (COS) and, in a portion of the samples, dimethylsulfide were also detected. The mean H2S emission rate was almost the same from twigs of Norway spruce (6.2 pmol kg(-1) dry s(-1)) and Blue spruce trees (5.9 pmol kg(-1) dw s(-1)) but it was approximately 18 times higher for Scots pine (110 pmol kg(-1) dw s(-1)). The percentage of SO2 detoxification via H2S emission was calculated on the basis of data on SO2 fluxes. It is only about 1% for Norway spruce and Blue spruce but about 10% for Scots pine.