Occurrence of dyes in the Yamaska River, Quebec

A study of the Yamaska River in Quebec in the period 1985-1987 has revealed the occurrence of fifteen dyes in water, suspended solids and sediment downstream from textile mills. The dyes were found in 1985 and 1986, but not in 1987, possibly because of improved waste treatment procedures. The most contaminated area was downstream from Granby, which has the largest concentration of textile mills in the basin. Three dyes were positively identified--Disperse Red 60, Disperse Blue 26 and Disperse Blue 79, the most widely used dye in the world. In addition, a mutagenic degradation product of Disperse Blue 79, 2-bromo-4,6-dinitroaniline, was identified in sediment at a location about 6 km downstream from Granby. This product is a result of the reductive cleavage of the azo bond of Disperse Blue 79 in anaerobic sediments.