ORGANIC HALOGENS IN UNPOLLUTED WATERS AND LARGE BODIES OF WATER RECEIVING BLEACH PLANT EFFLUENTS

We reviewed and updated recently performed studies of organic halogens in unpolluted waters and two large bodies of water receiving bleach plant effluents-Lake Vattern in Sweden and the Baltic Sea. All water samples contained measurable amounts of adsorbable organic halogens (AOX); the highest concentrations (up to 200-mu-g Cl/L) were observed in humic lakes not exposed to any industrial discharges. Analysis of chlorophenols revealed that there is a long-distance transport (> 100 km) of chloroguaiacols from bleach plants to remote parts of receiving waters. However, there was no evidence of chlorinated organics from bleach plants accumulating over several years in the water phase. One chlorophenol, 2,4,6-trichlorophenol, and its methylated analogue, 2,4,6-trichloroanisole, were also detected in surface waters considered to be unpolluted. Mass balance calculations showed that different processes in terrestrial environments make large contributions of AOX; enzyme-mediated chlorination of humic substances is a plausible explanation to the widespread occurrence of organic halogens.