Mineral characterization of a major source of the traffic-related non-exhaust emissions

Nowadays the relative contribution of non-exhaust emissions (NEEs) to the total traffic-related PM10 has increased to 60–90% (Piscitello et al., 2021) due to engine developments, tightening emission standards and the growing share of electric vehicles. Among the major sources of NEEs, urban road dust is a complex mixture of particles from different primary sources, such as resuspension from soil, construction and demolition works and traffic-related sources. The respirable fraction of urban road dust may contain potentially hazardous pollutants which may cause adverse health effects.

A special mobile sampling unit (Jancsek-Turóczi et al., 2013) was successfully deployed to collect resuspended and respirable urban road dust (PM1−10) samples for source apportionment studies. The availability of bulk PM1−10 fraction of the collected road dust without a filter matrix facilitated the application of XRD method for the determination of the mineralogical composition. The identified main crystalline phases (calcite, quartz, dolomite, chlorite, plagioclase, alkali feldspar, mica and gypsum) in the PM1−10 fraction of resuspended road dust can be attributed to two major sources, namely construction/demolition works and soil resuspension, with a significant degree of overlap.

In order to further differentiate between the two major sources, resuspended road dust samples were collected on construction and demolition sites and from their vicinity in order to determine specific mineralogical tracer of construction works by XRD analysis. In three of the six urban road dust samples, we have successfully identified pseudowollastonite, a mineral phase of CaSiO₃ that is exclusively formed in high temperature processes of cement production (Santos et al., 2019). It can occur in relatively abundant in slags and cement, but is virtually absent in native rocks since its formation requires a complex interplay of specific factors that barely happens in nature (Seryotkin et al., 2012). In our study we prove that this crystalline phase can be an excellent tracer for assessing the contribution of the construction and demolition works to common mineral particles found in ambient PM10 and resuspended road dust.

 

This work was supported by the Sustainable Development and Technologies National Programme of the Hungarian Academy of Sciences (FFT NP FTA) and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.

 

Piscitello, A., Bianco, C., Casasso, A., Sethi, R. (2021) Sci. Total Environ. 766, 144440.

Jancsek-Turóczi, B., Hoffer, A., Nyírő-Kósa, I., Gelencsér, A. (2013) J. Aerosol Sci. 65, 69-76.

Seryotkin, Y.V., Sokol, E.V., Kokh, S.N. (2012) Lithos 134-135, 75-90.

Santos, D., Santos, R.L., Pereira, J., Horta, R.B., Colaco, R., Paradiso, P. (2019) Materials 12, 3457.