[Capacity Simulation Method Based on Regional Transfer Matrix and PM_2.5 Concentration Target Constraint]

Atmospheric environmental capacity is an important reference in environmental planning. To meet the PM_2.5 standard, a new method is proposed to balance the capacity among cities of Guangdong, with screening of the most unfavorable meteorological year and combining it with the regional transportation calculated by the CAMx-PSAT module. Pollutant overloading and capacity scenarios were also calculated. The results showed that, under the constraints of the cities' annual PM_2.5 ≤ 35 μg·m^-3, the capacities of SO₂, NO, NH₃, and PM_2.5 in Guangdong were about 6.8×10⁵ tons, 1.35×10⁶ tons, 4.6×10⁵ tons, and 5.1×10⁵ tons, respectively. Based on the benchmark scenario, SO₂ emissions in Guangdong were overloaded by 10%, and the emissions of NO, NH₃, and PM_2.5 exceeded by 12%, 9%, and 20%, respectively, compared to those of the capacity scenario. Ranked by the number of overloaded species in Guangdong, the cities of Guangzhou, Foshan, Zhongshan, and Qingyuan were on top. When achieving the capacity scenario, the annual PM_2.5 concentration in Guangdong was about 30 μg·m^-3, which meets the national secondary ambient air quality standard.