Science. 1985 Nov 1;230(4725):566-70. doi: 10.1126/science.230.4725.566.
Experiments were conducted to measure the photosynthetic response of three crop and four tree species to realistic concentrations of ozone and (for tree species only) simulated acidic rain. The ozone concentrations were representative of those found in clean ambient air, in mildly to moderately polluted air such as occurs in much of the United States during the summer, and in more heavily polluted air. However, the highest concentrations of ozone used were lower than those found regularly in the Los Angeles area. The mean pH of the simulated acid rain treatments ranged from more alkaline to much more acidic than the mean pH of precipitation in the United States. Exposure to any increase in ozone reduced net photosynthesis in all species tested. In contrast, acidic rain had no negative effect on photosynthesis in tree species, and no interaction between ozone and acidic rain was observed. Ozone-induced reductions in photosynthesis were related to declines in growth or yield. Species with higher stomatal conductances and thus higher potential for pollutant uptake exhibited greater negative responses to similar ozone treatments. Since exposure to ozone concentrations typical of levels of the pollutant observed in the eastern half of the United States reduced the rates of net photosynthesis of all species tested, reductions in net photosynthesis may be occurring over much of the eastern United States.
进行了实验以测量三种作物和四种树木物种对现实浓度的臭氧和（仅针对树木物种）模拟酸雨的光合作用反应。臭氧浓度代表了清洁环境空气中、美国夏季大部分地区轻度到中度污染空气中以及污染更严重空气中发现的浓度。然而，所用的最高臭氧浓度低于洛杉矶地区经常发现的浓度。模拟酸雨处理的平均 pH 值范围从比美国降水的平均 pH 值更碱性到更酸性。暴露于任何臭氧增加都会降低所有测试物种的净光合作用。相比之下，酸雨对树木物种的光合作用没有负面影响，也没有观察到臭氧和酸雨之间的相互作用。臭氧引起的光合作用减少与生长或产量下降有关。具有较高气孔导度的物种，因此具有更高的污染物吸收潜力，对类似的臭氧处理表现出更大的负面反应。由于暴露于美国东部观察到的污染物水平的典型臭氧浓度降低了所有测试物种的净光合作用率，因此净光合作用的减少可能正在美国东部的大部分地区发生。
