FORMATION OF MUTAGENIC ORGANIC BY-PRODUCTS AND AOX BY CHLORINATION OFFRACTIONS OF HUMIC WATER

Dissolved organic matter from a lake was isolated and fractionated by sorbtion on an XAD-I column and then separated into humic and fulvic a cids. After chlorine- treatment of the fractions 2-chloro-3-dichlorome thyl-4-oxo-butenoic acid, MX, and three related compounds were determi ned by means of GC/MS in the selected ion monitoring mode. Mutagenicit y was determined in the Ames test and adsorbable organic halogen (AOX) was determined by adsorption to activated carbon followed by neutron activation analysis. AOX formation per unit organic carbon was similar in the hydrophilic and hydrophobic fractions, but the hydrophobic fra ction produced more mutagenic activity and MX than the hydrophilic one . The humic acid fraction produced slightly more mutagenicity and MX t han the fulvic acid fraction per unit organic carbon. However, there a re more fulvic acids than humic acids in natural waters and therefore fulvic acids contribute more to the mutagenicity and MX formation in c hlorinated natural waters.