Trace Metals and Polycyclic Aromatic Hydrocarbons in the Snow Cover of the City of Nizhnevartovsk (Western Siberia, Russia)

Abstract

The city of Nizhnevartovsk is one of the centers of oil production in Western Siberia (Russia). A survey of the contents of trace metals and metalloids (TMMs) and polycyclic aromatic hydrocarbons (PAHs) in the snow cover was conducted there. It was aimed to study insoluble particles in the snow where the predominant fraction of pollutants in urban areas is concentrated. In contrast to the background area, the deposition of TMMs in Nizhnevartovsk increases by 1-2 orders of magnitude. The deposition of V and Mn increases by 37 and 88 times, respectively, and the deposition of W increases at most (by 98 times). Abrasion of spikes of winter tires, abrasion of metal parts of vehicles, and combustion of motor fuels cause the pollution with W, Co, and V, respectively. The total content of 12 EPA PAHs in the particulate fraction of snow in the urban area averaged 148.2 ng l^-1, and the deposition rate was 17.0 μg/m². In contrast to the background area, the fraction of high molecular weight 5-6-ring PAHs significantly increases in the city, especially dibenzo(a,h)anthracene (DahA). The indicative ratios of PAHs showed that the snowpack composition was influenced by both petrogenic and pyrogenic sources. The proportion of pyrogenic sources is the highest in the low-rise residential area due to fuel combustion to produce heat and burning of household waste. The impact of motor transport is also major and is manifested in the maximum pollution in areas of heavy traffic. No emissions of PAHs from oil spills from the nearby Samotlor oil field have been identified. It is concluded that the hydrocarbon pollution of the atmosphere from the field weakens during the winter period compared to the warm season. Application of the integral TDF index characterizes the majority (72%) of the studied samples as lowly polluted, 24% of the observation sites are classified as moderately polluted, and one (4%), as highly polluted. The maximum TDF values are observed in the industrial area. The data obtained during the study allowed us to identify the central areas and sites along the roads with the heaviest traffic as the most contaminated areas of the city. This study can be a reference for air pollution monitoring in Nizhnevartovsk.