Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons in typical oasis soil of north-western China and the bacterial community response

Oases environments in oases to be sensitive to anthropogenic activity because of ecological fragility. Polycyclic aromatic hydrocarbon (PAH) pollution resulting from anthropogenic activity leads to ecological degradation in oases. To examine the impact of anthropogenic activity on the oasis ecological environment, the present study focused on the spatial distribution and source apportionment of soil PAHs and bacterial community responses in typical oases in Xinjiang, China. The results showed that the soil PAH level were higher in the city centres of Urumqi (9-6340 mu g kg- 1), Aksu (8-957 mu g kg- 1) and Korla (8-1103 mu g kg- 1) and lower in the centres of Hotan city (11-268 mu g kg- 1) and Qira county (7-163 mu g kg- 1). Source apportionment suggested that gasoline emissions, diesel emissions, vehicle emissions, coal combustion, coke processing and biomass burning were the sources of soil PAHs. The integrated lifetime cancer risks of soil PAH exceeding the guideline safety values (10-6) recommended by United States Environmental Protection Agency. The ingestion and dermal exposure pathways caused the greatest health risk (contribution <= 82%). Additionally, in the soil with low PAH concentrations, the richness and evenness of the soil bacterial community were great, and the molecular ecological network (MEN) structure was complex. Among populations, Proteobacteria and Actinobacteria (relative abundance >= 17%) are the main dominant species in the bacterial communities and the keystone species in the MEN.

Automated summary

Human activities lead to PAH pollution and significant impact on oasis ecological environments, especially in urban centers. Soil PAH concentrations vary in different oasis regions, with health risks mainly from ingestion and dermal exposure pathways. In soils with low PAH concentrations, the bacterial community is diverse and enriched, showing a complex ecological network structure.