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Effects of ozone and aerosol pollution on photosynthesis of poplar leaves |
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| Affiliation: | State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China University of Chinese Academy of Sciences, Beijing 100049, China |
| Abstract: | Aims The rapid economic growth has led to serious atmospheric compound pollution in China. Ozone and aerosol are the two main air pollutants that could greatly alter the photosynthesis of plants. Ozone often inhibits leaf photosynthesis through phototoxic effect, while aerosol could increase leaf photosynthesis through diffuse fertilization effect. This paper aims to investigate the relative impact of ozone and aerosol on leaf photosynthesis under atmospheric compound pollution. Methods We planted Populus × canadensis at three sites along the air pollution gradient around Beijing metropolitan area. During the growing season of 2012-2013, ozone concentration (AOT40), aerosol optical depth (AOD), air temperature, photosynthetically active radiation (PAR) and photosynthetic rates of leaves were measured at these sites. Important findings The results showed that: (1) AOT40 increased with increasing air temperature and AOD. Aerosol loadings reduced the external canopy PAR but increased internal canopy PAR. (2) The photosynthesis of sun leaves positively correlated with AOD and air temperature, and negatively correlated with AOT40, while the photosynthetic of shade leaves was positively correlated with AOD. (3) For sun leaves, ozone was the most important factor affecting their photosynthetic rates. Aerosol’s positive effect on photosynthesis of sun leaves was compensated by the negative effect of ozone. Meanwhile, by scattering solar radiation, aerosol contributed the most to the increased photosynthesis of the shade leaves. Overall, our results indicated that ozone and aerosol induced different impacts on the photosynthesis of sun and shade leaves, suggesting that plants with different canopy structures and ozone sensitivity may respond differently to compound pollution. Our results also indicated that aerosol and ozone pollution need to be controlled simultaneously to protect the productivity and function of ecosystem. |
| Keywords: | atmospheric compound pollution photosynthesis ozone aerosol sun leaf shade leaf |
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