Using Si, Al and Fe as Tracers for Source Apportionment of Air Pollutants in Lake Baikal Snowpack

Abstract

The aim of this study was to select chemical species characterized by distinctly different proportions in natural and anthropogenic particulate matter that could be used as tracers for air pollutant sources. The end-member mixing approach, based on the observation that the chemical species in snow closely correlated with land use are those that exhibit differences in concentrations across the different types of anthropogenic wastes, was used for source apportionment. The concentrations of Si and Fe normalized to Al were used as tracers in the mixing equations. Mixing diagrams showed that the major pollution sources (in descending order) are oil, coal, and wood combustion. The traces of several minor sources, such as aluminum production plants, pulp and paper mills, steel rust, and natural aluminosilicates, were also detected. It was found that the fingerprint of diesel engines on snow is similar to that of oil combustion; thus, future research of the role of diesel engines in air pollution will be needed. The insufficient precision of source apportionment is probably due to different combinations of pollution sources in different areas. Thus, principles for the delineation of areas affected by different source combinations should be the subject of further studies.

Source Apportionment of Particulate Matter in Urban Snowpack Using End-Member Mixing Analysis and Positive Matrix Factorization Model

“…The lowest Ca/Al, Fe/Al, Si/Al ratios and highest Al/Si ratios in snow PM observed in Irkutsk and Slyudyanka cities were due to fossil fuel combustion [40]. The values of Si/Al and Al/Si ratios typical for fuel combustion were several times higher and lower than Si/Al and Al/Si values typical for aluminum production, respectively.…”

“…Factor 1 was characterized by the relatively high concentrations of Al, Ti and Fe; however, the factor's contribution to concentrations of these elements is low. The Al, Ti and Fe could originate either from non-exhaust traffic emission or fossil fuel combustion; however, the quite low value of Si/Al ratio argue in favor of combustion of fuel oil [40]. The contribution of Factor 1 to concentrations of Cr, Ni, Cu and Pb was highest among the other factors that also argues in favor of pyrogenic origin of those metals.…”

“…That was probably due to local meteorological conditions. Slyudyanka is located away from regional northwest air mass transfer (from Angara River valley towards to Selenga River delta) and surrounded by mountains that favors the prevalence of local and circum-Baikal winds transporting pollutants from one costal area to another [40]. The average concentrations of Ca, Ti, Cu, Sr in Slyudyanka were highest, whereas the concentrations of Si, Ni, Zn, Pb were lowest among the three cities studied.…”

“…These can be major ions [30,31], organic substances [32][33][34][35], metals [36,37] or contributions of different PM fractions to total PM mass [38]. However, regardless of the merits of PMF, the results obtained using this model may be misleading because the reconstructed source profiles may be combinations of several real source profiles, or may not exist at all [39,40]. One more difficulty with using PMF is the need for comprehensive information on PM composition: The greater the input data the higher the consistency between the real and modelled source profiles and source contributions to pollution [41].…”

Insoluble Particles in the Snowpack of the Ob River Basin (Western Siberia) a 2800 km Submeridional Profile

“…In boreal and subarctic regions, both dissolved and particulate fractions of snow water reflect the chemistry of the winter atmosphere, when the land is covered by snow and the water surfaces are covered by ice. During winter, the input of mineral compounds from adjacent regions is Atmosphere 2020, 11, 1184 2 of 11 minimal, and the main factor controlling the chemical composition of snow is long-range, atmospheric transfer and transportation of anthropogenic particles over hundreds and thousands of kilometers from regional towns [19,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”