Sulfur dioxide , emitted by the industrial production and domestic burning fuel , and nitrogen oxides , emitted by the car exhausts and burning petrol are absorbed by the rain , forming larger raindrops , and falling on the ground . this is called acid rain . the main fuel in china is coal , which emits mainly sulfur dioxide , so the acid rain in china is sulfuric acid type of acid rain 工业生产、民用生活燃烧煤炭排放出来的二氧化硫，燃烧石油以及汽车尾气排放出来的氮氧化物，经过云内成雨过程，即水气凝结在硫酸根、硝酸根等凝结核上，发生液相氧化反应，形成硫酸雨滴在下降过程中不断合并、吸附、冲刷其它含酸雨滴和含酸气体，形成较大雨滴，最后降落在地面上，形成了酸雨。
In order to cope with the complexity and the multiplicity of environmental samples , a reasonable combination of the fluorescence analysis with each kind of separation technology , through which nitrite is determined in a more accurate , more sensitivity and lower detection limit , is another research direction in the future 为了适应环境样品的多样性和复杂性，实现荧光分析与各种分离技术的合理组合，以更准确、更灵敏和更低检出限测定样品中亚硝酸根也是今后的研究方向。
