ESTIMATION OF NITRIC ACID GAS DRY DEPOSITION IN VIET NAM

This article uses dry deposition calculating method to estimate Nitric acid (HNO3) gas dry deposition and analyze, evaluate trend of HNO3 gas dry deposition in recent years. The results present that HNO3 gas concentration is from 0.02 to 0.83 ppb and Yen Bai site has the highest HNO3 gas emission in 2020 and 2021. High HNO3 gas emission focuses on summer and spring at Northern’s sites. HNO3 gas emission at Southern sites is lower than that of Northern ones. HNO3 gas dry deposition is from 6.63 kg/ha/year to 10.26 kg/ha/year and the highest HNO3 gas dry deposition value is in 2021. Ha Noi site has the highest HNO3 gas dry deposition value in 2019, 2020, and 2022 while Yen Bai site is in 2021 and 2023. HNO3 gas dry deposition value at Southern sites is lower than Northern sites. The highest monthly HNO3 gas dry deposition is from June to August at Yen Bai site in 2021 and May in 2020. Annual average HNO3 gas dry deposition of 2021 is higher than other years. HNO3 gas dry deposition in recent years has an increasing trend.