Analysis of atmospheric emissions associated with on-road and inland waterway transport in Vietnam: Past, current and future control scenarios

Abstract

On-road traffic usually receives higher priority for emissions control than other transport modes. To justify the emission control priority, our study provides comprehensive analysis of annual emissions from on-road traffic and inland waterway transport in Vietnam during 2010–2019. On-road transport emissions, both running and start-up, were quantified with bottom-up approach using provincial activity data and relevant emission factors which were scrutinized to reflect actual fleet technologies in each province. Inland waterway transport emissions, estimated for the first time for the country, were calculated using fuel consumption and registered vessel data. Total emissions progressively increased during the decade. On-road transport contributed predominantly, sharing from 85% for SO2 to 99.9% for CH4 in 2019. Before enforcement of lower fuel S content being effective in 2016, inland waterway contributed more to SO2 emissions (>59%). Engine start-up emissions of the on-road traffic, which have not been previously quantified, contributed significantly, e.g., up to 53% of the total evaporative VOC of the total on-road emissions in 2019. The large motorcycle (MC) fleet shared most of gaseous emissions, while diesel fleet contributed significantly to emissions of PM, carbonaceous aerosol, NOx, and SO2. Nearly half of total 20-yr GWP from the two transport modes in 2019 was from black carbon. EuroIV scenario reduces emissions by 2–72% while that of MC-50 (cut-down 50% of MC activities) reduces by 0.2–7%. The emission inventory results provide science-based information to prioritize control efforts and are useful for air quality modeling to quantify impacts of different interventions on ambient air quality.