Determination of NO x emission rates of sailing inland ships from on-shore measurements.

Inland ships are an important source of NO _x , especially for cities along busy waterways. The amount and effect of these emissions depends on the traffic density and the NO _x emission rates of the individual vessels. Monitoring of ship emissions is usually carried out using in situ instruments on land and often relative NO _x emission factors, e.g. the amount of emitted pollutants per amount of burnt fuel is reported, but in this study, NO _x emission rates in g s-1 are investigated. Within the EU Life project Clean Inland Shipping (CLINSH), a new approach to calculate NO _x emission rates from data of in situ measurement stations has been developed and is presented in this study. Peaks (i.e. elevated concentrations) of NO _x were assigned to the corresponding source ships and each ship passage was simulated using a Gaussian-puff-model in order to derive the emission rate. In total over 32900 ship passages have been monitored over the course of 4 years. The emission rates of NO _x were investigated with respect to ship speed, ship size and direction of travel. Individual comparisons of the on-shore emission rates and those made on-board of selected CLINSH ships show good agreement. Also the emission rates are of similar magnitude as emission factors from previous studies. In contrast to relative emission factors (in grams per kilogram fuel), the emission rates (in grams per second) do not need further knowledge about the fuel consumption of the ship and can therefore be used directly to investigate the effect of ship traffic on air quality. [ABSTRACT FROM AUTHOR]