Behaviour and spatial and temporal variations of polychlorinated biphenyls and lindane in the urban atmosphere of the Paris area, France

This paper presents the results of a five year study (1986–1991) of the contamination of the Paris area atmosphere by polychlorinated biphenyls (PCBs) and lindane. The main processes affecting their behaviour and fate such as vapour/particle partitioning and washout are described and modelled. The spatial and temporal variations of the concentrations of the compounds are assessed. PCBs did not exhibit a clear seasonal cycle, whilst lindane showed systematically higher concentrations in Spring, reflecting the agricultural use of this pesticide. The mean annual concentration of lindane in the atmosphere was stable during the period of study. PCBs concentrations showed a twofold decrease since 1986, presumably in part because of the effectiveness of pollution prevention measures. Recent spatial variations in PCBs or lindane were not very important and the most recent concentrations recorded (2–6 ng m−3 for PCBs and 1.5 ngm−3 for lindane) were in line with levels commonly reported in the literature. PCBs as a whole were predominantly in the vapour phase (78% on top of the St Jacques Tower in 1989–1990). The amount associated with the particle phase was linked to temperature and increased during winter. The behaviour of individual components showed wide differences reflecting their varying physico-chemical properties: IUPAC no. 18 was not detectable in the particle phase whilst no. 180 was for 70% in the particle phase. Lindane was found only in the vapour phase. The overall washout ratio W (ng m−3 rain/ngm−3 air) was 34 × 103 for total PCBs and 79 × 103 for lindane. It varied between 21 × 103 for component IUPAC no. 28 to 235 × 103 for n 180. Dry deposition amounted to 35% of the total deposition for PCBs and 1 % for lindane. The associated deposition velocity for Aroclor 1254 was 0.12 cm s−1.