Contribution of ship emissions to the concentration and deposition of pollutants in Europe: Seasonal and spatial variation

Abstract

We studied the effects of ship emissions on the annual and seasonal concentrations and depositions of pollutants in Europe using the regional air quality model CAMx with and without ship emissions for 2006. Ship emissions cause a decrease in annual ozone mixing ratios around the English Channel and the North Sea, whereas they lead to an increase (4–14 %) in the Mediterranean region. They also cause an increase in PM2.5 concentrations over the Mediterranean Sea (up to 80 %) and in the North Sea and Baltic Sea as well as along the coastal areas (10–15 %). Increased concentrations of the primary particles are predicted only along the shipping routes, whereas concentrations of the secondary pollutants are affected over a larger area. Particulate sulfate concentrations increase in the Mediterranean and the North Sea while elevated particulate nitrate levels are found especially around the Benelux area and northern Italy where there are high NH3 land-based emissions. Our model results show that not only the air concentrations of pollutants are affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes, especially in the Mediterranean Sea. The effects are found to be larger in summer.