BROMOCHLOROMETHOXYBENZENES IN THE MARINE TROPOSPHERE OF THE ATLANTIC-OCEAN - A GROUP OF ORGANOHALOGENS WITH MIXED BIOGENIC AND ANTHROPOGENIC ORIGIN

Halogenated methoxybenzenes (anisoles) are ubiquitous organics in the environment, although they are not produced in technical quantities. T o elucidate the sources of the various halogented anisoles in the mari ne troposphere, their concentrations were measured in air from the Eas tern Atlantic Ocean between 40 degrees N and 57 degrees S during the n orth-south transect ANT XI/1 of the German RV Polarstern. A typical pa ttern of eight congeners was observed. it consisted of 2,4,6-trichloro -, 2,3,4,6-tetrachloro-, pentacbloro-, 2,4-dibromo-, 2,6-dibromo-, 2,4 ,6-tribromo-, and two unidentified dibromochloroanisoles. The meridion al concentration profiles, the comparison of the patterns of the relat ive concentrations of bromo- and chloroanisoles, as well as principal component analysis of the concentrations of the halogenated anisoles i ndicate an anthropogenic origin for the chloroanisoles and a biogenic origin for the bromoanisoles. The pattern of the chloroanisoles differ s for the two hemispheres. It seems to reflect the global pollution wi th chlorophenols which have a maximum of anthropogenic input in the No rthern Hemisphere. The pattern of the bromoanisoles is characterized b y regional biogenic sources, which leads to high concentrations of bro moanisoles south of 20 degrees N in contrast to low concentrations of chloroanisoles in this part of the Atlantic Ocean.