Modeling of the Concentrations of Ultrafine Particles in the Plumes of Ships in the Vicinity of Major Harbors

Abstract

Marine traffic in harbors can be responsible for significant atmospheric concentrations of ultrafine particles (UFPs), which have widely recognized negative effects on human health. It is therefore essential to model and measure the time evolution of the number size distributions and chemical composition of UFPs in ship exhaust to assess the resulting exposure in the vicinity of shipping routes. In this study, a sequential modelling chain was developed and applied, in combination with the data measured and collected in major harbor areas in the cities of Helsinki and Turku in Finland, during winter and summer in 2010–2011. The models described ship emissions, atmospheric dispersion, and aerosol dynamics, complemented with a time–microenvironment–activity model to estimate the short-term UFP exposure. We estimated the dilution ratio during the initial fast expansion of the exhaust plume to be approximately equal to eight. This dispersion regime resulted in a fully formed nucleation mode (denoted as Nuc2). Different selected modelling assumptions about the chemical composition of Nuc2 did not have an effect on the formation of nucleation mode particles. Aerosol model simulations of the dispersing ship plume also revealed a partially formed nucleation mode (Nuc1; peaking at 1.5 nm), consisting of freshly nucleated sulfate particles and condensed organics that were produced within the first few seconds. However, subsequent growth of the new particles was limited, due to efficient scavenging by the larger particles originating from the ship exhaust. The transport of UFPs downwind of the ship track increased the hourly mean UFP concentrations in the neighboring residential areas by a factor of two or more up to a distance of 3600 m, compared with the corresponding UFP concentrations in the urban background. The substantially increased UFP concentrations due to ship traffic significantly affected the daily mean exposures in residential areas located in the vicinity of the harbors.

Effects of marine fuel sulfur restrictions on particle number concentrations and size distributions in ship plumes in the Baltic Sea

“…The FSC limits and emissions control areas are described in more detail in IMO MARPOL Annex VI, Regulation 14 (IMO, 2020b). The decline in the real FSC of marine vessels has been shown to follow the FSC restrictions well (Kattner et al, 2015;Pirjola et al, 2014); therefore, the FSC limits can be expected to resemble the real maximum FSC of the fuels used. However, Pirjola et al (2014) reported that during the FSC restriction period of 1.50 m/m% (before July 2010), some vessels were already using fuels with an FSC of less than 1.00 m/m%.…”

Advances in Air Quality Research – Current and Emerging Challenges

“…As for road traffic, the influence of ship emissions on air quality induces pollution gradients in the city. Karl et al (2020) thus found out that, in residential areas up to 3600m from a major harbour, the ultrafine particle concentrations were increased by a factor of two or more compared with the urban background.…”

Development of a moving point source model for shipping emission dispersion modeling in EPISODE–CityChem v1.3

“…Murena et al (2018) also treated the ships in maneuvering and navigation modes as fixed point emission sources. In another group of studies, a line emission source model was widely applied to simulate the moving ships in maneuvering or cruising mode (Poplawski et al, 2011;Kotrikla et al, 2013;Deniz and Kilic, 2010;Lucialli et al, 2011). In the line source (LS) model setup, the ship emission is assumed to be constantly emitted along the entire ship route, which is assumed to be a straight line.…”

“…In the line source (LS) model setup, the ship emission is assumed to be constantly emitted along the entire ship route, which is assumed to be a straight line. In some other cases, ships in hoteling or maneuvering modes were treated as area sources (Kotrikla et al, 2013;Formentin, 2017;Abrutytė et al, 2014); however, this assumption is not commonly used to treat ship emissions.…”