| Polycyclic aromatic hydrocarbons (PAHs) is a group of ubiquitous persistent toxic compounds, PAHs are mainly originated from incomplete combustion of fossil fuel and biomass. Lanzhou is an important industrial city in the northwest of China, and the fuel consumption in the Lanzhou area is mainly from coal, from which PAHs pollution can't be neglected. By now, the source, state, and multimedia environmental fate or behavior of PAHs hadn't been elucidated. Hence, air samples were collected using an improved high volume active air sampler August,2008 to July,2009 in Lanzhou City. Concentrations of polycyclic aromatic hydrocarbons(PAHs) in both gas and particle phases were measured. The distribution of PAHs in atmosphere of Lanzhou city has obviously seasonal characteristics. The average concentration of the sixteen kinds of PAHs in winter was highest, obviously higher than the other three seasons. Lower ring PAHs dominated in the gas phase, while the major higher ring PAHs were adsorbed on particle phase.When dust weather occurred, PAHs concentrations in TSP will increase significantly, much higher than non-dust weather. It is indicated that dust weather have direct effect on PAHs concentration of air in the Lanzhou area. Regarding to the meteorological parameters, precipitation distinctly lowered the PAHs concentration in TSP; in non-heating period, PAHs concentrations in both TSP and gas fall with the temperature goes up, but there is no obvious relation between concentration and temperature in heating period; the increase of wind speed causes the decrease of PAHs concentrations in both TSP and gas in the heating period, but relation between PAHs concentrations in both TSP and gas and wind speed varied with aromatic rings of PAHs and levels of wind speed in the non-heating period.Diagnostic ratios of some individual PAHs and principal component analysis were applied for qualitative source apportionment. According to above-mentioned analytical result, PAHs in atmosphere environment in Lanzhou originated both from combustion sources and the petrogenic source, showing a mixed PAHs input pattern.Based on the observed concentrations of polycyclic aromatic hydrocarbons in 11 surface water samples from the Lanzhou reach of the Yellow River and LC50 values of 6-38 of aquatic organisms, the quotient method and two probabilistic risk approaches were adopted to characterize ecological risks of benzo[a]pyrene, fluoranthene, and pyrene in water from the Lanzhou reach of the Yellow River. The results indicated that three residual PAHs carries some ecological risk. While at the lower exposure level (percent of species affected less than 1%), ecological risk of benzo[a]pyrene is the highest and that of pyrene was the lowest. Conversely, at the higher exposure level (percent of species affected more than 3%), the ecological risk of 3 individual PAHs followed the order of pyrene >benzo[a]pyrene> fluoranthene. In addition, comparing the results among the three approaches, the joint probability curve was the most appropriate method for risk characterization of PAHs in the Lanzhou reach of the Yellow River.The polycyclic aromatic hydrocarbons (PAHs) pollution of the Lanzhou reach of the Yellow River has been more and more serious in recent year. In order to investigate potential health risk to human bodies caused by organic pollutants of polycyclic aromatic hydrocarbons in waters there, based on water quality monitoring data from 11 sampling sites in the Lanzhou reach of the Yellow River in 2004, a preliminary assessment of the health risk caused by ingestion from drinking water and dermal contact with shower water was performed by using a health risk method of US EPA. The results showed that the non-carcinogenic risk indexes of organic pollutants of polycyclic aromatic hydrocarbons were far below 1. The carcinogenic risk index of benzo[a]pyrene was below 10"4. The carcinogenic risk value of benzo[a]pyrene at sampling site 1(S1) located in the Bapan Gorge of Xigu district was relatively high. Among all the sampling sites, the sampling site 1(S1) in the Bapan Gorge of Xigu district was the most heavily polluted, and might carry a higher health risk. Compared with other regions in China, the carcinogenic risk value of benzo[a]pyrene in the Lanzhou reach of the Yellow River were higher. The routine treatment technology of tap water can not remove effectively the trace organic pollutants (such as PAHs, etc). Therefore, the PAHs pollution of surface water carries a great health risk, especially when surface water is used as a drinking-water resource.Based on some foreign standards of soil PAHs assessment, regional environment risk assessment of topsoil PAHs in the Lanzhou area was done. Naphthalene, fluoranthene, chrysene and indeno[123-c,d]Pyrene in the topsoil of the Lanzhou area are exceed the standard of Holland.A level III fugacity model was used to calculate the transfer, transport, and fate of benzo[a]pyrene, fluoranthene, and pyrene in different compartments in the Lanzhou area. The results indicated that: advection inflows in air and combustion of fossil fuel were the major sources of benzo[a]pyrene, fluoranthene, and pyrene in this area, and soil was the largest storage of benzo[a]pyrene, fluoranthene, and pyrene, accounting for more than 90% of the total amount of residual. Degradations in soil, air, and advection outflow of atmosphere were main route of output. The transfer of between air to soil, and air to water surface is the most important transfer process among different compartments. The reliability of the model was verified by the coincidence of the calculated and the measured concentration in the same period. The key model parameters were identified through sensitivity analysis.
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