Size-fractionated carbonaceous particles and climate effects in the eastern region of Myanmar

This study reports on an investigation of fine and coarse carbonaceous particulate matters(PM)in Tachileik,eastern Myanmar,during the dry and wet seasons of 2022.The carbon compositions,including organic carbon(OC)and elemental carbon(EC),in each size(PM10-2.5,PM2.5-1.0,and PM1.0-0.5)were determined by a carbon analyzer.The average total mass concentration of the three fractions of particle samples during the dry season was higher(51.23±23.86μg/m3)than that of the wet season(14.00±5.26μg/m3).The results indicate that OC and EC levels were highest for PM1.0-0.5 during the dry season and the sizes were similar for both seasons.The OC/EC ratios varied in different seasons,from 1.93 to 4.40 and 4.13 to 5.25 in the dry and wet seasons,respectively.EC was sub-divided into char-EC and soot-EC;the char-EC/soot-EC in the dry season was higher than in the wet season,signifying that biomass burning is the main particle source during the dry season.However,vehicle emissions dominated during the wet season.The effective carbon ratio(ECR)suggested that finer particles contributed more to global warming.This information is important in terms of air quality control and mitigation in Myanmar and elsewhere.