146
P. Sahu
6.6.2 Analytical Methods
The USEPA has developed methods to detect ClO 4
− based on selectivity, sensitivity,
precision, accuracy and method robustness (Wagner et al. 2007). After the USEPA
established Method 314.0 for analysing ClO 4
− (Wagner et al. 2006), numerous standard methods (i.e. 314.1, 314.2, 331.0 and 332.0) have been established that can
detect ClO 4
− concentrations in the ng/L range.
Ion chromatography is considered as the basic method of analysing ClO 4
− in
drinking water and environmental samples. Standard Method 314 (ion chromatography) had been established and released by EPA’s Office of Ground Water and
Drinking Water for the analysis of drinking water (Hautman et al. 1999) and can
be applied for aqueous samples of ClO 4
− having a concentration of 4 µg/L. This
method has been validated in drinking water only, and no guidance is provided for
use with soils and biota. For aqueous and soil samples, similar Method 9058 (ion
chromatography) has been issued by the EPA’s Office of Solid Waste and Emergency Response (USEPA 2000). The reporting limit of 0.5–1 µg/L for ClO 4
− is
achievable. Many forensic approaches have been proposed regarding ClO 4
− source
identification and age dating. Stable isotope analysis is also carried out to identify
the sources of ClO 4
− . Triple-oxygen isotope ratios
17 O/
16 O and
18 O/
16 O ratios and
37 Cl/
35 Cl ratio are used to distinguish anthropogenic and naturally occurring sources
of ClO 4
− (Coleman and Coates 2004; Sturchio et al. 2003). To confirm the origin
of ClO 4
− in soil, whether evaporate or marine, scanning electron microscopy and/or
X-ray diffraction method may be used (Srinivasan and Viraraghavan 2009).
6.7 Remediation of Perchlorate
Many biological and physicochemical processes are available for the remediation of
ClO 4
− in contaminated environments. Some of the important processes are briefly
described in the following sections.
6.7.1 Biological Treatment Methods
To remove ClO 4
− , biological treatment methods are used very frequently as they are
efficient as well as eco-friendly. This may be of two types: in situ and ex situ. In
situ mechanism includes biodegradation and phytoremediation, whereas the use of
bioreactor for ClO 4
− removal is an ex situ mechanism.
P. Sahu
6.6.2 Analytical Methods
The USEPA has developed methods to detect ClO 4
− based on selectivity, sensitivity,
precision, accuracy and method robustness (Wagner et al. 2007). After the USEPA
established Method 314.0 for analysing ClO 4
− (Wagner et al. 2006), numerous standard methods (i.e. 314.1, 314.2, 331.0 and 332.0) have been established that can
detect ClO 4
− concentrations in the ng/L range.
Ion chromatography is considered as the basic method of analysing ClO 4
− in
drinking water and environmental samples. Standard Method 314 (ion chromatography) had been established and released by EPA’s Office of Ground Water and
Drinking Water for the analysis of drinking water (Hautman et al. 1999) and can
be applied for aqueous samples of ClO 4
− having a concentration of 4 µg/L. This
method has been validated in drinking water only, and no guidance is provided for
use with soils and biota. For aqueous and soil samples, similar Method 9058 (ion
chromatography) has been issued by the EPA’s Office of Solid Waste and Emergency Response (USEPA 2000). The reporting limit of 0.5–1 µg/L for ClO 4
− is
achievable. Many forensic approaches have been proposed regarding ClO 4
− source
identification and age dating. Stable isotope analysis is also carried out to identify
the sources of ClO 4
− . Triple-oxygen isotope ratios
17 O/
16 O and
18 O/
16 O ratios and
37 Cl/
35 Cl ratio are used to distinguish anthropogenic and naturally occurring sources
of ClO 4
− (Coleman and Coates 2004; Sturchio et al. 2003). To confirm the origin
of ClO 4
− in soil, whether evaporate or marine, scanning electron microscopy and/or
X-ray diffraction method may be used (Srinivasan and Viraraghavan 2009).
6.7 Remediation of Perchlorate
Many biological and physicochemical processes are available for the remediation of
ClO 4
− in contaminated environments. Some of the important processes are briefly
described in the following sections.
6.7.1 Biological Treatment Methods
To remove ClO 4
− , biological treatment methods are used very frequently as they are
efficient as well as eco-friendly. This may be of two types: in situ and ex situ. In
situ mechanism includes biodegradation and phytoremediation, whereas the use of
bioreactor for ClO 4
− removal is an ex situ mechanism.