Effects of Combined Pollution of SO2 and PAHs on Seed Germination and Growth of Wheat Seedlings in Shanxi Industrial and Mining Area
山西工矿区土壤二氧化硫与多环芳烃复合污染对小麦种子萌发和幼苗生长的影响

Seed germination, plant height, root elongation and underground biomass of wheat seedlings in fresh mixed-loess soils contaminated by sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) with different concentrations were studied to reveal the ecotoxical effects of combined pollution of SO2 and PAHs. The results indicated that seed germination was not sensitive to single or combined pollution of PAHs and SO 2. Root elongation and plant height were affected by single pollution of PAHs or SO2 to different extents. Wheat seedlings growth was slightly improved at lower concentrations, while inhibited at higher concentrations. Plant height of wheat seedlings were correlated well with SO2 concentrations (r=-0.954, P<0.05), but the correlation was not well with the concentrations of PAHs. Under combined pollution conditions, the joint action of SO2 and PAHs on plant height or root elongation reflected multiple synergism. Specifically, in the case of low concentration (SO2<500mg·kg-1), it showed synergistic stimulation, while the concentration of SO2 ranged from 500~1 000 mg·kg-1, it showed synergistic inhibition. By single pollution of PAHs or SO2, underground biomass of wheat seedlings significantly correlated with concentrations of PAHs or SO2 (rPAHs=-0.953, rSO2=-0.916, P<0.05). The combined effects of PAHs and SO2 on underground biomass of wheat seedlings showed synergistic stimulation when the concentration of SO2 was at 10 mg·kg-1. It was showed synergistic inhibition when the concentration of SO2 was up to 1 000 mg·kg-1 and the concentration of PAHs was up to 50~100 mg·kg-1. By using the stepwise regression method, it was showed that plant height or root elongation of wheat seedlings were subject to the combined effect of PAHs and SO2. Meanwhile, SO2 was the main factor which affected the underground biomass of wheat seedlings under combined pollution conditions.