Emerging contaminants in groundwater - NERC Open Research ...

OR/11/013
5.1.2 Perfluorinated hydrocarbons (including PFOS and PFOA)
Perfluorinated hydrocarbons have been used for over 50 years for a range of industrial
applications (Sections 3.4 and 3.7). The main compounds of interest are PFOS and PFOA,
both of which have been widely detected in the environment and human and animal tissues
(Environment Agency, 2008a). PFOS is persistent, bio-accumulative and toxic (OECD,
2002).
The potential for these contaminants to occur in groundwater was highlighted in the aftermath
of the Buncefield incident. An explosion at the Buncefield oil depot in Hertfordshire in 2005
led to major fires: 750 000 litres of foam concentrate and 55 million litres of water were used
to extinguish them (BMIIB, 2006). Some of the foam contained PFOS and this was detected
in groundwaters in the vicinity following the incident. The Buncefield Investigation report
points out that no sampling for PFOS was done prior to the incident so the possibility that it
originated prior to the incident cannot be ruled out.
The manufacture and use of PFOS is being phased out due to concerns about its persistence in
the environment. The Environment Agency reviewed the available data on the
physicochemical properties of perfluorinated hydrocarbons in a 2008 report: data reported
included solubility and Kow. They also undertook laboratory experiments to determine
partition coefficients (Kd) between some perfluorinated compounds and aquifer materials
from England and Wales (Environment Agency, 2008). Partition coefficients were shown to
vary significantly between different aquifer materials and with differing concentrations of the
compound. For example, a 10 µg/L solution of PFOA exhibited a Kd of 0.97 with Mercia
Mudstone, while the Kd between the same solution and Lower Oxford Clay was 13 8, an order
of magnitude larger. The availability of more-accurate property values enables better
environmental assessments of the fate and behaviour of these compounds. Replacements for
PFOS and PFOA include perfluorobutane sulfonate (PBFS) (Environment Agency, 2008). Be
5.1.3 Other source terms
Other types of compounds anticipated to require treatment in urban wastes and waters are set
out in Gibs et al. (2007) and Stackelberg et al. (2007) (Table 5.3). These include detergent
degradates, flame retardants and plasticisers, and fragrances and flavourings. Gibs et al.
(2007) and Stackelberg et al. (2007) also considered a wide range of pharmaceuticals and a
small set of pesticides which are not being considered in this section.
Table 5.3 Urban organic micropollutants excluding pharmaceuticals from Gibs et al. (2007) and
Stackelberg et al. (2007).
Class Examples
Detergent degradates 4-nonyl-phenol, diethoxynonylphenol, diethoxyoctyl-phenol,
ethoxyoctyl-phenol
Flame retardants and
plasticisers
bisphenol a, diethyl hexylphthalate, diethylphthalate , tetrabromodiphenyl
ether, tri(2-butoxyethyl) phosphate, tributyl phosphate, triphenyl
phosphate
Polyaromatic hydrocarbons anthracene, benzo[α]pyrene, fluoranthene, naphthalene, pyrene
Fragrances and flavourings acetophenone, camphor, galaxolide, isoborneol, menthol, skatol, tonalide
Plant and animal steroids b-sitosterol, b-stigmasterol, cholesterol
Repellents DEET
Misc 1,4-dichlorobenzene, 4-cresol, anthraquinone, benzophenone, isophorone,
tetrachloroethene, triclosan., triethyl citrate
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