✍ Scribed by Katja Hüve; Andreas Dittrich; Gerald Kindermann; Stefan Slovik; Ulrich Heber
No coin nor oath required. For personal study only.
Contents of organic sulfur, sulfate and the inorganic cations K +, Ca 2+, Mg 2+, Mn 2+ and Na + were compared in needles of three conifer species differing in tolerance to chronic SO2 immissions. Sulfate and organic sulfur compounds were also measured in bark and wood. Field material was collected from Norway Spruce (Picea abies (L.) Karst.), Colorado Spruce (Picea pungens Engelm.) and Scots Pine (Pinus sylvestris L.) at sites where the SO 2 concentration in air was high, and at another site where it was low. In general, sulfate contents were higher but cation contents lower at the sites where SO2 concentrations were high than where they were low. Up to ll4mmol .(kg DW) -1 sulfate was measured in fouryear-old needles of Norway Spruce from the Erzgebirge (annual mean of SO2 in air 32 nl -1-~). Sulfate accumulation in this SO2-sensitive conifer increased with SO2 concentration in ambient air and with needle age, indicating that the main part of the sulfate resulted from the oxidative detoxification of SO2. Loss of inorganic cations from ageing needles was reduced, or cation levels even increased, with increasing needle age, while sulfate accumulated. Apparently, cations served as counter-ions for sulfate, which is sequestered in the vacuoles. Individual trees differed in regard to the nature of cations which accumulated with sulfate. Calcium, potassium and magnesium were the dominating cations. Sodium levels were very low. Needles of the SO2-tolerant conifers Colorado Spruce and Scots Pine growing next to Norway Spruce in the Erzgebirge did not accumulate, or accumulated less, sulfate with increasing needle age as compared to needles of Norway Spruce. However, somewhat more sulfate was found in the bark of the SO2-tolerant species than in the bark of Norway Spruce. Scots Pine contained distinctly more sulfate in the wood than the other conifers. Since accumulation of organic sulfur compounds could not be
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