The macroscopic mechanisms and associated atmospheric precursor environmental capacities that lead to secondary fine particle pollution

摘要

This paper establishes the kinetic equations in atmospheric chemistry that describe the macroscopic mechanisms of secondary fine particle pollution generated by precursors during atmospheric self-purification.The dynamic and static solutions of these equations can be applied to calculate quantitative relationships between the concentration ratio of precursors and secondary fine particles as well as the physical clearance power of the atmosphere,chemical reaction rate,and the scale of a contaminated area.The dynamic solution presented here therefore corresponds with a theoretical formula for calculating the overall rate constant for the oxidation reaction of reducing pollutants in the actual atmosphere based on their local concentrations and meteorological monitoring data.In addition,the static solution presented in this paper reveals the functional relationship between the concentration of secondary fine particles and precursor emission rate as well as atmospheric self-purification capacity.This result can be applied to determine the atmospheric environmental capacity of a precursor.Hourly records collected over the last 40 years from 378 weather stations in China's Mainland as well as the spatiotemporal distribution sequence of overall oxidation reaction rates from precursors show that when the reference concentration limit of secondary fine particles is100μmol m-3,the atmospheric environmental capacity of total precursors canbe calculated as 24890×1010 mol yr-1.Thus,when the annual average concentration limit of given fine particles is 35μg m-3 and the ratio of sulfate and nitrate to 30%and 20%of the total amount of fine particles,the capacities of SO2,NOx and NH3 are 1255,1344,and 832(1010g yr-1),respectively.The clearance density of precursors for different return periods across China's Mainland under above conditions are also provided in this study.