Annual balances of hexachlorocyclohexanes, polychlorinated biphenyls and triazines in the German Bight

During the PRISMA-Project concentrations of hexachlorocyclohexanes (alpha-HCH, gamma-HCH), polychlorinated biphenyls (the 'DIN-PCBs': PCB 28, PCB 52, PCB 101, PCB 153, PCB 138, PCB 180), and triazines (atrazine, simazine, terbutylazine) were determined in the German Eight within the water column and in rain water. In addition, the HCHs, and PCBs were also analysed in sediment samples. The concentration values were combined with average lateral inflow and outflow rates of water masses into and out of the German Eight and with the respective inflow rates of the rivers Elbe, Weser and Ems. Thus an estimation of the annual balances of these compounds was accessible that allowed the following conclusions: a loss of 2 t yr(-1) gamma-HCH between input into and output out of the German Eight has to be stated, while more alpha-HCH is leaving this area at its northern boundary, This phenomenon can be explained by the different stability of the two HCH isomers. The mobility of PCBs has to be largely attributed to sediment transport, where during the summer period a larger amount is being transported into than out of the German Eight, while during spring the opposite observation was made. Furthermore, evidence is presented that stresses the importance of the riverine input of triazines to the German Eight. The role of their atmospheric input is not very pronounced within the coastal area, however, it has to be taken into consideration for the more distant North Sea regions. This holds, in particular, for the triazines, where atmospheric transport may become significant already in North Sea areas outside the plume of the river Elbe. (C) 1997 Elsevier Science Ltd.