Emissions of NO, NO ₂ and PM from inland shipping

Particulate matter (PM) and nitrogen oxides NO _x (NO _x =  NO ₂+ NO) are key species for urban air quality in Europe and are emitted by mobile sources. According to European recommendations, a significant fraction of road freight should be shifted to waterborne transport in the future. In order to better consider this emission change pattern in future emission inventories, in the present study inland water transport emissions of NO _x, CO ₂ and PM were investigated under real world conditions on the river Rhine, Germany, in 2013. An average NO ₂ ∕ NO _x emission ratio of 0.08 ± 0.02 was obtained, which is indicative of ship diesel engines without exhaust gas aftertreatment systems. For all measured motor ship types and operation conditions, overall weighted average emission indices (EIs), as emitted mass of pollutant per kg burnt fuel of EI _NOx =  54 ± 4 g kg ⁻¹ and a lower limit EI _PM1 0.125emnobreak ≥  2.0 ± 0.3 g kg ⁻¹, were obtained. EIs for NO _x and PM ₁ were found to be in the range of 20–161 and  ≥  0.2–8.1 g kg ⁻¹ respectively. A comparison with threshold values of national German guidelines shows that the NO _x emissions of all investigated motor ship types are above the threshold values, while the obtained lower limit PM ₁ emissions are just under. To reduce NO _x emissions to acceptable values, implementation of exhaust gas aftertreatment systems is recommended.