Atmospheric deposition of organochlorines (PCBs and pesticides) in northern France

Bulk deposition measurements were made in northern France for a number of organochlorines (PCBs, HCB, pp′DDE, alpha-HCH and gamma-HCH) over a 1-y period, at urban, semi-rural, rural and forest sites located in accordance with prevailing wind direction. The west–east rise of PCB bulk deposition (average annual values as ∑7) ranged from 12.2 to 46.8 ng l−1 and showed the anthropogenic influence arising from towns, industries, storage areas and landfills over continental areas. The values were maximal at the urban site 3, Paris (122 ng l−1) and were still high at the eastern site 6, Abreschviller near landfills (62 ng l−1). Also, the highest annual deposits were found at sites 3 and 6 (Paris and Abreschviller), 38.6 and 47.3 μg m−2, respectively, i.e. 3.6 and 4 times higher than the western site value: Pleumeur. A temporal trend was observed, at the urban site where a rise occurred (up to 441 ng l−1) in March and April. PCB distribution according to the chlorination degree displayed high proportions of 3 Cl and 4 Cl congeners, particularly in the forest area. Annual gamma-hexachlorocyclohexane (gamma-HCH) concentration values at sites 1 (Ouessant) and 2 (Pleumeur) were close to the background noise (1.7 ng l−1). At the agricultural (4) and the urban (3) sites, values were maximal (19.2 and 15.9 ng l−1) with peaks in spring and autumn. At Pleumeur, without any local input, negative correlations were found between PCB/temperature (r=−0.503, p<0.05), HCB/temperature (r=−0.549, p<0.05) and gamma-HCH/temperature (r=−0.675, p<0.01). A clear influence of south-west winds upon the magnitude of PCB fluxes throughout the sites was noticed. Whereas there was no global decrease of PCB contamination since 1986, the general trend of gamma-HCH total deposits was a 10-time fall, as a result of the restricting legislation in use.