USES OF CHLORIDE BROMIDE RATIOS IN STUDIES OF POTABLE WATER/

In natural ground water systems, both chlorine and bromine occur prima rily as monovalent anions, chloride and bromide. Although dissolution or precipitation of halite, biological activity in the root zone, anio n sorption, and exchange can affect chloride/bromide ratios in some se ttings, movement of the ions in potable ground water is most often con servative. Atmospheric precipitation will generally have mass ratios b etween 50 and 150; shallow ground water, between 100 and 200; domestic sewage, between 300 and 600; water affected by dissolution of halite, between 1000 and 10,000; and summer runoff from urban streets, betwee n 10 and 100. These, and other distinctive elemental ratios, are usefu l in the reconstruction of the origin and movement of ground water, as illustrated by case studies investigating sources of salinity in grou nd water from Alberta, Kansas, and Arizona, and infiltration rates and pathways at Yucca Mountain, Nevada.