Ground-level ozone in the Mekong Delta region: precursors, meteorological factors, and regional transport

Abstract

The Mekong Delta region (MDR), also known as Vietnam's rice bowl, produced a bountiful harvest of about 23.8 million tons in 2020, accounting for 55.7% of the country's total production, providing food security for 20% of the world population. With the rapid pace of industrialisation and urbanisation, concentration of ozone in the lower atmosphere has risen to a level that reduces crop yields, especially rice, and is, therefore, the subject of research. This study has a goals to simulate the spatio-temporal distribution of ground-level ozone in the area, also to evaluate the impact of precursor emissions and meteorological factors on spatio-temporal distributions of concentration. The study area was divided into six agro-ecological zones to clarify the role of emissions in each zone. The simulation resultsshowed that the ground-level O 3 in the MDR ranged from 40.39 µg/m 3 to 52.13 µg/m 3 . In six agroecological zones, the average annual ground-level O 3 concentration was relatively high, and was the highest in areas six (CZ) and seven (CPZ), with 46.11 µg/m 3 and 46.41 µg/m 3 , respectively. In each zone, the annual average O 3 concentration tended to gradually increase from the inner delta to coastal areas.Two types of precursors, NO x and NMVOCs, are the main contributors to O 3 pollution, with the largest contribution coming from zone 1 (FAZ) with 91.5 thousand tons of NO x /year and 455.2 thousand tons of NMVOCs/year. Among the meteorological factors considered, relative humidity (RH) and surface pressure (P) were the two main factors that contributed to the increase in ground-level ozone. The spatio-temporal distribution of ground-level O 3 in the MDR was in uenced by emission precursors from different zones as well as meteorological factors. The present results can help policymakers formulate plans for agroindustrial development in the entire region.

Assessment of rice yield and economic losses caused by ground-level O3 exposure in the Mekong delta region, Vietnam

“…In this study, two nested domains consisting of the first domain (D01) combined with the second domain (D02) were established in the coupled WRF/CMAQ models; details of the domain technical parameters are shown in Table S3 . Specific information for the model configuration, emission inventories, chemical transport mechanisms, initial/boundary conditions, and modelling performance verification can be found in detail in previous studies [ [65] , [66] , [67] , [68] ]. The simulation efficiency of ground-level O 3 concentration by this system was assessed based on a wide range of statistical indicators, including the Nash efficiency index, mean bias (MB), root mean-squared error (RMSE), normalised mean bias (NMB), normalised mean gross errors (NME), and R correlation coefficient from our previous studies [ 67 , 68 ].…”

Đánh giá các tác động sức khỏe cộng đồng do phơi nhiễm ngắn hạn ô nhiễm PM2.5: Nghiên cứu điển hình tại tỉnh Bình Dương

“…Trong tháng 1/2019, nồng độ PM2. ) cũng được đánh giá dựa trên kinh nghiệm từ cách tiếp cận của mô hình hồi quy tuyến tính đa biến như ở nghiên cứu [49]. Như vậy, kết quả từ quá trình hồi quy đã đạt được với phương trình là y = 191,17 + 11,31x1 + 3,21x2 + 0,01x3 + 3,13x4 -17,55x5 cùng với một hệ số tương quan Pearson khá tốt R = 0,91 (hệ số R 2 = 0,82).…”