[Potential of purifying SO2 of main tree species and their planting quota in Shenyang area].

The total potential of purifying SO2 of main tree species was studied by using the combination of field measurement and fumigation experiment in this paper. The integrated value of purifying SO2 including total bimass, absorption intensity of SO2, and absorption-transformation periods of sulfur by trees was 4.39 x 10(6) kg, which was accounted for 3.66% of total sulfur released per year in Shenyang. It indicated that the maximum daily potential of purifying SO2 of trees might be 12.19 kg.km-2. Supposed that the average annual absorption capacity for sulfur of trees in Shenyang was 0.70 kg per tree and the average annual absorption capacity for sulfur of broad-leaved trees was 1.35 kg.tree-1, 88.88 million broad-leaved trees would be required to purify the annual released SO2 thoroughly. This number was equivalent to 12.9 times of existing trees. On the conditions of strengthening environmental protection and decreasing 20% of annual released sulfur, if the broad-leaved trees was double of the present number, SO2 content in air might be below 0.06 mg.m-3 and Shenyang would become a standardizing city with clear air.