Study On Polycyclic Aromatic Hydrocarbons In Dust In Shanghai

The distribution and concentration of polycyclic aromatic hydrocarbons (PAHs) in the dust are paid special attention because of their mutagenic and carcinogenic properties. 16 PAHs have been put into the list of priority monitoring pollutants. Dust is one of main atmospheric components in the urbanized area. With the fast development of population and motors during the last decades, the atmospheric pollution has become one of main issues in Shanghai. And in the Report of Environmental Quality of Shanghai in 2003, dust is identified as the most abundant pollutant in urban, suburban and rural areas. But by now, the research on distribution and source of PAHs concentrations of dust in Shanghai remains scarce. The objective of this work was to determine the spatio-temporal distribution of EPA 16 priority PAHs pollution in dust collected from 13 sites in Shanghai, China.Moreover, as one main kind of pollution in indoor environment, PAHs emitted from dust in computers and air-conditions were investigated too.There are 3 main contents in this work, as following:1. Parameters affecting the collection efficiencies of 16 priority PAHs were assessed according to the extraction efficiency, and the best and simple conditions of SFE were confirmed to extract 16 priority PAHs from dust. The characterization of extracts was carried out by gas chromatography with mass detector (GC/MS).2. The spatio-temporal distribution of PAHs in 13 dust sample sites in urban area of Shanghai from Nov, 2004 to Nov, 2005 was investigated. The results showed that the average concentrations of PAHs in one year were about 2.26-22.94 μg g^-1. The most serious polluted sites were located in the area of heavy traffic. Phe, Flu, Pyr, Chry, BbF and BaP were the most abundant PAHs, the total contribution of which in all PAHs were in the range of 61-68%, with a average value 64%. PAHs owning 4-ring and 5-ring were the primary components, some of which were the main genotoxic PAHs to humans. Traffic emission, especially gasoline engine, was the main source of PAHs in spring, summer and autumn of Shanghai in 2005. And coal combustion was another source in autumn and winter of 2004 besides traffic emission. The concentrations of PAHs in Shanghai were similar to those reported elsewhere. The photolysis of some PAHs was investigated according to the ratio of BeP/BaP.3. This study was undertaken with the aim of determining levels of PAHs in dust collected from computers and air-conditions in indoor environment, analyzing the source of PAHs, and assessing the potential exposure of PAHs from computers. Thelevels of PAHs in dust samples from computers were from 8.22 μg g^-1 to 42.04 μg g^-1. BbF and BgP were the most abundant PAHs. The levels of PAHs in many computers were usually higher than those in samples from traffic area. Smoking was one main source of PAHs in computers dust. The potential exposure of PAHs from computers was also evaluated, and our results showed that people may exposure suspended particulates containing PAHs up to 3.22 ng m^-3 which are just sprayed out from computers. We supposed that parts of PAHs in computers may be emitted from the heated plastic material out of chips in computers when they are running, and be adsorbed on dust deposited on these components. One new source of PAHs maybe exists in computers, and some future experiments were needed to confirm this conclusion.The levels of PAHs in air-conditions were a litter lower than those in computers, which were mainly varying in the range of 3.64-16.62 μg g^-1. The using frequency of air-conditions and the conditions of ventilation in different rooms were the main factors to control the levels of PAHs in air-conditions.The shape and surface of particulates were confirmed through the photos of dust by SEM and TEM, which demonstrated the potential harm of dust to humans.