Formation mechanism and control strategy for particulate nitrate in China

Over the past decade, fine particulate matter (PM) pollution in China has been abated significantly, benefiting from strict emission control measures, but particulate nitrate continues to rise. Here, we review the progress in particulate nitrate (pNO(3)(-)) pollution characterization, nitrate formation mechanisms, and the proposed control strategies in China. The spatial and temporal distributions of pNO(3)(-) are summarized. The current status of knowledge on the chemical mechanism is updated, and the significance of its formation pathways is assessed by various approaches such as field observation and modelling of nitrate production rate, as well as isotopic analysis. The factors impacting pNO(3)(-) formation and the corresponding pollution regulation strategies are discussed, in which the importance of atmospheric oxidation capacity and ammonia are addressed. Finally, the challenges and open questions in pNO(3)(-) pollution control in China are outlined. (c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

In China, over the past decade, fine particulate matter (PM) pollution has been significantly reduced due to strict emission control measures, but particulate nitrate (pNO(3)(-)) continues to increase. This review summarizes the progress in characterizing pNO(3)(-) pollution, understanding nitrate formation mechanisms, and proposing control strategies in China. The spatial and temporal distributions of pNO(3)(-) are summarized, and the importance of atmospheric oxidation capacity and ammonia in pNO(3)(-) formation is discussed. The challenges and unresolved questions in pNO(3)(-) pollution control in China are outlined.