A simple and rapid method for the highly sensitive determination of polycyclic aromatic hydrocarbons (PAHs) from airborne fine particulate matter (PM2.5) in an urban environment of Delhi was developed. The target compounds were 10 of the 16 United States Environmental Protection Agency (US-EPA) priority PAHs: fluoranthene, pyrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo[a]pyrene, dibenzo(ah)anthracene, benzo(ghi)perylene, indeno(1,2,3-cd)pyrene. For collecting the samples, the following two locations in Delhi (India) were chosen: ITO and Okhla Industrial Area.  Two sets of samples at these locations of were collected for the purpose of investigation. The fine particulate matter samples were collected on glass fiber filter papers for 24h, from which the PAHs were extracted using dichloromethane (DCM) and hexane using ultrasonication method. Comparison of the characteristic emission of spectra of PAHs with standard spectra indicated the degree of condensation of aromatic compounds present in the investigated mixtures. However, this identification could be more effective with the use of the respective values of Δλ parameter for each particular component of the mixture. It has been found that the concentration of the PAHs is maximum during the winter season and minimum during the summer and monsoon seasons at both the locations.

Residents in arid regions of northwest China, where dust storms are more common, are continually exposed to air pollution particularly fine particles of PM2.5 and PM10, causing health hazards to residents. Urban greening species have a strong dust retention capacity which is also available in arid conditions and should be chosen to reduce the impact of air pollution on people and the urban environment. In this paper, three common tree species in four different functional areas: Transportation area (TA), Residential area (RA), Industrial area (IA), and Clean area (CA) of Aksu City were selected to measure their foliar dust to select the matching trees for appropriate sites. The dust particle size distribution for PM2.5 and PM10 was analyzed to explore the particle size difference between foliar dust and natural landing dust. The largest particle size was recorded in IA (168.56 μm), while the smallest was found in CA (43.25 μm). Furthermore, Salix babylonica (S. babylonica) absorbed the highest PM2.5 and PM10, 0.15% and 1.39% respectively; while Ulmus densa (U. densa) absorbed the least PM2.5 and PM10, 0.08% and 0.37%. Platanus acerifolia (P. acerifolia) foliar dust particle density was the highest, and has stable dust retention capacity, while, S. babylonica foliar dust particulate density is the lowest under the same conditions (height/location, pollution exposition, weather). Our findings concluded that the average values of dust diameters in the four areas differed significantly. It is concluded that P. acerifolia is the best performer in removing dust in different functional urban areas and S. babylonica was more suitable for CA because of having the capacity to remove fine particle matter.

The contamination status of heavy metals in urban environment changes frequently with the industrial structure adjustment, energy conservation and emission reduction and thus requires timely investigation. Based on enrichment factor, multivariate statistical analysis and isotope fingerprinting, we assessed comprehensively the inputs and sources of heavy metals in different samples from an urban area that was less impacted by leaded gasoline exhaust. The road dust contained relatively high levels of Cr, Pb and Zn (with enrichment factor >2) that originated from both exhaust and non-exhaust traffic emissions, while the moss plants could accumulate high levels of Pb and Zn from the deposition of traffic exhaust emission. This suggest that the traffic emission is still an important source of metals in the urban area although gasoline is currently lead free. On the contrary, the occurrences of metals in the urban soils were controlled by natural sources and non-traffic anthropogenic emission. These findings revealed that different samples would receive different inputs of metals from different sources in the urban area, and the responsiveness and sensitiveness of these urban samples to metal inputs can be ranked as moss ≥ dust > soil. Taken together, our results suggested that in order to avoid generalizing and get detail source information, multi-samples and multi-measures must be adopted in the assessment of integrated urban environmental quality.