Aliphatic hydrocarbons (n-alkanes) associated with fine particulate matter were determined in the ambient air of urban,industrial and coastal areas in Tianjin,China,where intensive coal burning for industrial and domestic purpose takes place,n-Alkane homologues from C12 to C35 were quantifiable in all samples with C20-C31 being the most abundant species.Average concentrations of the total n-alkanes were 148.7,250.1 and 842.0 ng/m3 in July,April and January,respectively.Seasonal variations were mainly attributed to ambient temperature changes and coal combustion for residential heating.Among the three studied areas,the highest levels of n-alkanes were observed in the industrial complex in winter and spring,but in summer the coastal alkane concentration moved up to the highest.A mono-modai distribution for n-alkanes was observed in spring and summer with odd carbon number predominance and a maximum centered at C27-C31,suggesting the release of plant wax into the atmosphere.The bimodal distribution with maxima at C22 and C26 observed in winter indicated a substantial influence of fossil fuel sources.All the CPIs (CPI1,CPI2,CPI3) values,varying between 0.64 and 1.97,indicated the influence of anthropogenic emissions on fine organic aerosols.The estimated contributions of plant wax to total n-alkanes were on average of 12.9%,19.1% and 26.1% for winter,spring and summer,respectively.