Uses of Chloride/Bromide Ratios in Studies of Potable Water

Abstract

In natural ground water systems, both chlorine and bromine occur primarily as monovalent anions, chloride and bromide. Although dissolution or precipitation of halite, biological activity in the root zone, anion sorption, and exchange can affect chloride/bromide ratios in some settings, movement of the ions in potable ground water is most often conservative. Atmospheric precipitation will generally have mass ratios between 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, between 10 and 100. These, and other distinctive elemental ratios, are useful in the reconstruction of the origin and movement of ground water, as illustrated by case studies investigating sources of salinity in ground water from Alberta, Kansas, and Arizona, and infiltration rates and pathways at Yucca Mountain, Nevada.

Nitrate, sulphate and chloride contents in public drinking water supplies in Sicily, Italy

“…Natural sources of sulphate and chloride are seawater and the dissolution of evaporitic rocks, and the main anthropogenic sources are urban, industrial and agricultural wastewater. Different origins of these contaminants have often been distinguished on the basis of their bromide-tochloride ratio (Davis et al 1998).…”

Using hydrochemical and isotopic data to determine sources of recharge and groundwater evolution in an arid region: a case study in the upper–middle reaches of the Shule River basin, northwestern China

“…Many studies of the Br -/Cl -ratio of water suggest that it may be used as an indicator of the origin of salinity (Edmunds 1996;Cartwright et al 2006). In this study, the Br -/Cl -ratio of precipitation from Yumen City is 0.0015, which is typical of inland precipitation and depleted relative to sea water Environ Earth Sci (2015Sci ( ) 73:1901Sci ( -1915Sci ( 1909 (0.0035) (Davis et al 1998). The Br -/Cl -ratio in precipitation commonly behaves conservatively during transit through regional aquifers.…”

A Geochemical Approach to Determine Sources and Movement of Saline Groundwater in a Coastal Aquifer

“…As a result, during the evaporation process the insoluble residue (evaporite salt) is preferentially enriched in Cl and the residual solution is enriched in Br. The net result is that the Cl/Br ratio in groundwater samples affected by dissolution of halite in salt beds can be higher than 4000 (Davis et al 1998). The average Cl/Br ratio for groundwater samples in groups 1 and 2 is about 294 (s.d.…”

“…The chloride/bromide mass (Cl/Br) ratio in sea water is about 285 so most natural waters have a ratio close to this value; typical Cl/Br ratios in coastal groundwater are close to 290 (Davis et al 1998). Although Cl and Br are highly soluble, and both halides are typically conservative during subsurface transport (Jones et al 1999), Br is slightly more soluble than Cl.…”