8
Bromine [Br, 35]

8.1 INTRODUCTION
Bromine (Br) is a chemical element of the group 17 (halogen) in the periodic table
of elements. Its total contents of the Earth’s crust is estimated at 1–2.4 mg/kg (mean
2 mg/kg) and is relatively uniformly distributed among igneous rocks, whereas in
argillaceous sediments, it may be accumulated up to 10 mg/kg. Bromine is a very
volatile element and its salts are readily soluble and mobile in most environments.
It may, however, be concentrated in coal, at an average of 9.1 mg/kg, and accumulated up to 160 mg/kg (Finkelman 1999).
Elemental Br is a fuming red-brown liquid at room temperature, which is corrosive and toxic. Its chemical properties are similar to Cl and I. It is very reactive
chemically and can have several valence states. Its most common oxidation state is −1,
but may be from +1 to +7. However, as an one-electron atom, it can form only compounds with oxygen: Br 2 O, BrO 2 , BrO 3 . Minerals containing Br are not common,
owing to both its low abundance and high solubility. Its more often occurring minerals are bromyrite, AgBr; embolite, Ag(Cl,Br); and iodobromite, Ag(Cl,Br,I).
World total production (without the United States) of Br in 2010 was 380  kt,
of which China and Israel produced 140 kt and 130 kt, respectively (USGS 2011).
Commercially, Br is extracted from brine pools, mostly in the United States, Israel,
and China. Bromine compounds are used for various purposes: in well-drilling fluids, film photography, flame-retardant compounds such as polybrominated diphenyl
ethers (PBDEs), and as an intermediate in the manufacture of organic chemicals.
Considerable amounts of Br are used in agriculture, in various pesticides.
Ethylene bromide (C 2 H 4 Br 2 ) was an additive in gasoline (especially used in some
aircraft engines) in order to form volatile lead bromide (PbBr 2 ), which is exhausted
from the engines. This Br application has declined since 1970s. There has been also
a proposal of using Br to mitigate Hg emissions at the power plants, because Br compound bonds with Hg are more easily captured in flue-gas scrubbers than in HgCl 2
produced at many facilities. Now, half of Br produced is used for fire retardants
brominated flame retardant (BFR) (West 2008).
Reactive Br species of anthropogenic origin affect ozone by directly destroying it
and by reducing its production (von Glasow et al. 2004). As a result, many organobromide compounds that were formerly in common use (e.g., methyl bromide in
pesticides) have been abandoned.
8.2 SOILS
Boron content in soils is closely associated with soil types. Its lowest amounts, below
10 mg/kg, are in acid light sandy soils (Table 8.1). In heavy loamy soils, Br may be up
to 100 mg/kg. The highest Br concentrations, above 100 mg/kg are in volcanic ash
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