Seasonal variability of trace elements in fine particulate matter (PM2.5) in a coastal city of northern Poland – profile analysis and source identification

Abstract

A large group of trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn) was measured for the first time in 226 air samples collected at a coastal monitoring station in Gdynia (northern Poland), in the period from January 12th to August 30th, 2019. The 24 h measurements included fine particle (PM_2.5) concentrations, meteorological parameters and backward air mass trajectory analyses. The monthly mean PM_2.5 mass concentration ranged from 17.3 μg m⁻³ to 55.0 μg m⁻³, and the peak value of 167 μg m⁻³ was found in February. Overall, considerable differences in the trace element concentrations were observed. However, their seasonal distributions were not similar. In particular, elements such as Cd, Cu, Mo, Ni, V and Zn showed significantly higher concentrations (p < 0.05) in winter compared to spring or summer. The winter peak of trace element concentrations in PM_2.5 indicated that local power plants and fossil fuel/coal combustion in the residential sector were the major anthropogenic sources of air pollutants. Based on multivariate analysis (PCA) of the standardized database (14 elements and PM_2.5), a significant contribution of different sources and processes was identified, i.e. local traffic emission, local/regional coal/oil burning in power plants and domestic heating units, industrial activities, petrochemical industry and maritime transport. The Cu/Fe ratios revealed that both local traffic and brake-wear emission considerably influenced the chemical composition of PM_2.5. In addition, the results of the V/Ni ratio suggested local mixed industrial sources (petrochemical refinery and industrial plants) with possible contributions from the port area and shipping activities to the total PM_2.5 loadings. The local ship emission was more pronounced during the summer period.