Correction and source apportionment of vehicle emission factors obtained from Bolu Mountain Highway Tunnel, Turkey

Abstract

Total suspended particulate (TSP) samples were collected in the atmosphere of Bolu Mountain Highway Tunnel located on the axis of Edirne-Istanbul-Ankara on the main artery of Turkey, by using PUF samplers between 24 and June 29, 2018. Thirty-five major and trace metals, 11 water-soluble anions and cations, and OC and EC concentrations were determined at the entrance and the exit of the tunnel. Emission factor calculations were carried out with and without correction of the data set against crustal contributions. The non-crustal net concentration data set was used as an input for the factor analysis and factor analysis-multiple linear regression. Factor analysis identified five sources, namely, (1) road dust re-suspension, (2) road cover material and tyre wear abrasion, (3) brake pad solid lubricants, (4) diesel combustion emission, and (5) gasoline- LPG combustion emission. Contributions of identified sources on the TSP concentrations and emission factors were quantified by using the FA-MR technique and the results were discussed. Tin and Sb were identified and reported as the best marker for the brake-related non-exhaust emissions in the road tunnel. FA-MR results showed that 46, 60, 49, and 37% of Ba, Cu, Fe, and Mn, respectively were contributed by dust re-suspension. The main sources of EC (39%) and OC (49%) were observed to be gasoline-LPG emissions and 69% of sulfate and 62% of Pb in TSP fraction was contributed by diesel emission. Tin and Sb were mainly affected by the brake pad solid lubricant factor and 64% of Sn and 53% of Sb were contributed by this factor.