Trace Metals and Polycyclic Aromatic Hydrocarbons in the Snow Cover of the City of Nizhnevartovsk (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 share of pollutants in urban areas is concentrated. In contrast to the background areas, the deposition of TMMs in Nizhnevartovsk increases by 1–2 orders of magnitude. The deposition of Co, V, Mn, and As increases by 50–93 times, and the deposition of W increases at most (by 184 times on average). 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 areas, the share 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 Igeo index characterizes the majority of the studied samples as unpolluted, 24% of the observation sites are classified as moderately polluted, and one (4%), as highly polluted.