Distribution of particle-phase hydrocarbons, PAHs and OCPs in Tianjin, China

Aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) were determined in the total suspended particles (TSP) collected from 13 different locations in Tianjin, China, where intensive coal burning for domestic heating in winter takes place and a large quantity of pesticides had been produced and applied. Carbon preference index (CPI), carbon number maximum (Cmax) of n-alkane and plant wax index (%wax Cn) indicate that n-alkanes come from both biogenic and petrogenic sources, and biogenic source contributes more n-alkanes in autumn than in winter. Petroleum biomarkers as indicators of petrogenic source such as hopanes and steranes were also detected in both seasons’ samples. The sum of 16 PAH concentrations (∑PAH16) ranged from 69.3 to 2170 ng m−3 in winter and from 7.01 to 40.0 ng m−3 in autumn. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The results of a source diagnostic analysis suggest that PAHs in TSP mainly come from coal combustion. Seven OCPs (four hexachlorohexanes (HCHs) and three dichlorodipheny-trichloroethane and metabolites (DDTs)) were detected in most samples. Concentrations of the sum of α-, β-, δ- and γ-HCH (∑HCH) and the sum of p,p′-DDT, p,p′-DDD and p,p′-DDE (∑DDT) in autumn varied in the ranges of 0.002–0.9 ng m−3 and 0.025–2.21 ng m−3 with the average±standard deviation values of 0.127±0.241 ng m−3 and 0.239±0.546 ng m−3, respectively. In winter, ∑HCH and ∑DDT in TSP ranged from 0.071 to 5.35 ng m−3 and from 0.416 to 3.14 ng m−3 with the average±standard deviation values 1.05±1.88 ng m−3 and 0.839±0.713 ng m−3, respectively. Both of the illegal application of technical HCH and DDT and the volatilization from topsoil contributed to the particle-phase contents of HCHs and DDTs in the atmosphere.