Relative Sensitivity of Wetland Plants to SO2 Pollution

Abstract

Sulfur dioxide (SO2) is a major air pollutant and its concentration is increasing in many metropolitan and industrial areas. Identification of SO2 tolerant species that can be used in wetland plantings in those areas is needed. We compared SO2 toxicity and tolerance in 16 wetland herbaceous plants by examining SO2 effects on their photosynthetic apparatus. After leaf sections had been immersed in 0, 10, 20, 30, 40, 50, and 100 mmol/L NaHSO3 for 20 h, the maximum quantum yield and maximum electron transport rate of all 16 herbaceous plants decreased at different rates with increasing SO2 concentrations, suggesting that photosystem reaction centers were damaged due to SO2 stress, electron transport was inhibited, and photosynthetic efficiency decreased. Species were assigned to two groups, relatively resistant and sensitive, with dendrograms. The relatively resistant species were Typha angustifolia, Arundo donax, Echinochloa crusgalli var. mitis, Acorus gramineus, Phragmites australis, Zizania caduciflora, Carex scabrifolia, and Polygonum lapathifolium var. salicifolium. Sensitive species were Cayratia japonica, Eclipta prostrata, Solidago canadensis, Phacelurus latifolius, Scirpus triqueter, Inula linariaefolia, Kalimeris indica, and Alternanthera philoxeroides. Determining sensitivity of different wetland herbaceous plants to SO2 provides basic information for screening suitable species for wetland creation and restoration in urban areas.