50多年前,在美国加州的一大片柑橘树林里,柑橘树叶上出现了奇怪的斑点,后来叶子慢慢发黄脱落,树木枯死。专家分析后找到了原因,原来是城市汽车排放大量尾气,其中氮氧化物和碳氢化物在紫外线的照射下,生成了“光化学烟雾”,害死了柑橘。科学家还发现,有的植物对污染物 More than 50 years ago, in a large citrus grove in California, USA, weird spots appeared on the leaves of citrus trees. Afterwards, the leaves slowly turned yellow and the trees died. Expert analysis found the reason, the original city car exhaust a lot of exhaust, which nitrogen oxides and hydrocarbons in the ultraviolet light irradiation, the formation of a “photochemical smog”, killing the citrus. Scientists also found that some plants are contaminants