Specific pattern of tetrachloronaphthalenes in black cormorant

The ratio of 1,3,6,7-T4CN (no. 44) to 1,4,6,7-T4CN (no. 47) in the breast muscles and liver of black cormorant was 0.65 and 0.47, respectively, which is much higher than in environmental matrices such as sediment (0.015), plankton (0.033), mussel (0.023), crab (0.19), fishes (0.080), harbour porpoise (0.035), and juvenile (0.046) and adult (0.13) white-tailed sea eagle. 1,3,6,7-T4CN (no. 44) has two vicinal (adjacent) carbon atoms at αα positions (4,5- positions) unsubstituted with chlorine and seems to be much more persistent in black cormorant than 1,4,6,7-T4CN (no. 47), which has two vicinal carbon atoms at ββ positions (2,3- positions) unsubstituted with chlorine. Since 1,3,6,7-T4CN is not formed during gas phase chlorination of melted naphthalene, and was not found in technical Halowax formulations, its presence and relatively higher persistence in body of black cormorants indicate thermal formation, like in municipal waste combustion, and importance of such processes as a source of potentially toxic and persistent chloronaphthalenes in the environment.