北京远郊区臭氧污染及其对敏感植物叶片的伤害

臭氧(O3)是一种氧化性很强且生物危害很大的二次污染物.监测表明北京远郊区O3浓度高于近郊区和城区,经常超过敏感植物O3临界浓度(78.5μg/m3),自然植物的暴露剂量AOT40(超过78.5 μg/m3的空气O3浓度小时值累计量)值达到了98.9mg/m3,可能已经对植物生长造成危害.通过对远郊区O3浓度监测点(北京蟒山森林公园)26种乔木和灌木植物的调查,参考国外有关植物野外观测和模拟实验的植物O3伤害症状特征及植物O3伤害鉴别标准,发现其中15种植物出现了比较明显的O3伤害症状,表现为叶片出现点状、块状黄斑或褐色灼伤状干枯,表明北京远郊区的乔木和灌木已经受到了空气O3污染的危害.另外11种植物也出现了类似O3危害的伤害症状,需要进一步的研究验证是否由O3污染造成.

The ambient ozone pollution and foliar injury of the sensitive woody plants in Beijing exurban region

Ozone is a kind of secondary pollutant with high oxidability and strong biohazard. Long-term monitoring shows that the ozone concentration in Beijing exurban region is obviously higher than that of the urban and the suburb regions. The value of AOT40, from May to September reached 98.9mg/m³, which might already have negative influence on the growth of the wild plants. Via investigation near the long-term monitoring spot sited in Mangshan Forest Park, and referring to the assessment standard of visible symptoms of ozone injury which comes from investigation and imitation experiment of other countries, we found that 15 ozone-sensitive species with obvious ozone foliar injury symptoms among 26 woody plants,including arbor and shrubs, These 15 plants species include Grewia biloba var. parviflora, Lespedeza floribunda, Lespedeza tomentosa, Cotinus coggygria var. pubescens, Rhus typhina, Caragana frutex, Vitex negundo var. heterophylla, Prunus davidiana, Prunus sibirica, Ampelopsis humulifolia, Prunus triloba, Juglans mandshurica, Quercus wutaishanica, Rubus crataegifolius, Spiraea trilobata. The typical symptoms of the ozone foliar injury are dark stipple, mottling and tip burn. The colors of the injury symptoms changed from light to deep, including white, gray, yellow, brown and tan, the latter three were more usual. It showed that the woody plants in Beijing exurban region, including arbor and shrubs, had already suffered the hazard of ambient ozone. Besides, the other 11 woody plant species, including Pinus bungeana, Platycladus orientalis, Koelreuteria paniculata, Morus alba, Broussonetia papyrifera, Ziziphus jujuba var. spinosa, Pinus pumila, Pinus tabulaeformis, Ulmus pumila, Corylus mandshurica, Populus davidiana, showed similar symptoms of the previous plants. But further research is still necessary to investigate the factors lead to the injury symptoms.