Metal-bearing fine particle sources in a coastal industrialized environment

Abstract

Fine (<2.5μm), submicron (<1μm) and ultrafine (<100nm) atmospheric particles were collected during a 3-weeks campaign in a heavily industrialized area and physically and chemically characterized in order to determine their main sources. As a basis of comparison, the present one-year average EU limit value (25μg·m−3) and the WHO recommendation for PM2.5 (10μgm−3) were regularly exceeded during this campaign. Submicron particles (PM1) account for 55 to 70% of PM2.5 mass concentrations. A bi-modal size distribution, centered on 0.4 and 2.0μm, suggests two types of emissions: high temperature processes that liberate primary or secondary submicron particles and mechanical procedures in open air, or local traffic, which lead to the emission of coarser particles (>1μm). The trace elements As, Cd, Ni, Pb, Sb, V and Zn, characteristics of the local industrial activities display 60% to 85% of their mass in the submicron and ultrafine fractions and appear highly enriched, by reference to the crustal source. High atmospheric pressure periods, corresponding to northeasterly winds, induce the highest contributions of metalworking emissions and the highest PM2.5 concentrations (32.5±11.9μg·m−3). A Principal Component Analysis of the dataset produces 7 factors associated to metallurgy-, steelworks-, oil processing-, coal combustion-, neighboring traffic-, dust resuspension- and sea salt-sources, that explain the obtained concentrations. A Multiple Linear Regression Analysis confirms that Fe-Mn alloy refining, iron- and steel-making are the main sources (>40%) controlling metal concentrations in PM2.5. Less predictably, resuspended dust and fresh/aged sea salts are also significant contributors (≈20%). Considering the related health hazards, authorities should pay more attention to the exposure of people living in this area and the possible impact of fine particles in terms of public health.