Occurrence and Persistence of Dyes in a Canadian River

A study of the Yamaska River in Quebec, Canada, in the period 1985 - 1987 has revealed the occurrence of fifteen dyes in water, suspended solids and sediment downstream of textile mills. The most contaminated area was downstream of the city of 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 of Granby. This product is a result of the reductive cleavage of the azo bond of Disperse Blue 79 in anaerobic sediments. Most of the dyes found are expected to be moderately stable in aerobic environments, but may degrade under anaerobic conditions. This is the first demonstration of the occurrence of dyes in the Canadian environment.