Organic compounds in non-saline sediments 151
Koafmacher et al [137] employed a short clean-up of procedure followed by electron capture gas chromatography for the determination of octachlorodibenzo-p-dioxin
in soils using a furzed silica capillary gas chromatographic column. The technique was
suitable as a routine screening procedure for samples taken from contaminated sites.
Christman et al [138] gave details of procedures for extraction, clean-up, and
concentration of samples of soil prior to the determination of polychlorinated dibenzop-dioxins and polychlorinated dibenzofurans by gas chromatography and by gas
chromatography-mass spectrometry. Instrumental parameters are also included. Some
typical results are tabulated.
The benzene-water extraction gas chromatographic procedure described by Bride
et al [222] for the determination of aliphatic hydrocarbons in soil has also been applied
to the determination of polychlorinated dibenzo-p-dioxins in soil [140].
Otaka et al [140] have carried out a detailed study of the extractability of dioxins
from suspended sediments in water. These workers evaluated the extractability of dioxins from suspended substances in distributed water. Dioxins adsorbed on the collected
suspended solids were extracted by pressurised liquid extraction with various solvents.
High-poloarity solvents (acetone, alcohols) extracted considerably higher amounts of
some lower-chlorinated dibenzo-p-dioxins (LoCDD) than did low-polarity solvents
(dichloromethane, toluene), whereas the extracted amounts of higher-chlorinated
dibenzo-p-dioxins (HiCDDs) were roughly the same, regardless of the solvent. The
extractability of the LoCDDs depended on the isomer. Daily variations in quantities for
polychlorodibenzo dioxins organic matter and iron in the suspended soils were examined, and the results suggested that in the suspended solid, LoCDDs and HiCDDs were
associated, respectively, with raw water-derived organic matter and microparticles
sequestered in iron oxyl (hydr) oxide floc. It was also suggested that the low extractability of certain congeners was not attributable to the coexisting ferric compounds but
was probably attributable to organic matter with which they strongly associate.
Various other workers have discussed methodology for the determination of
µg kg
−1 levels of 176 polychlorodibenzo-p-dioxins and polychlorodibenzofurans in
sediments [46, 141–146] an silts [147]. The method described by Smith et al [46]
for the determination of polychlorodibenzo-p-dioxins and dibenzofurans in soils and
is also applicable to sediment. Taguchi [143] present preliminary results obtained in
a round robin inter-laboratory study on various techniques using gas chromatography and mass spectrometry for the determination of polychlorodibenzo-p-dioxins and
polychlorodibenzofurans in sediments. Clean-up techniques are discussed.
6.4 NITROGEN CONTAINING COMPOUNDS
Weber and Wolfe et al [147] have shown that aromatic diazocompounds in sediments
were readily degraded by an abiotic surface-mediated reaction. The exact nature of the
reducing agent was not determined, but it appeared to be associated with the sediment.
There was no apparent correlation between the rate of degradation and the measured
reduction potential of the diazo dyes. The rate of degradation appeared to be controlled
by the amount of partitioning on the sediment, with increasing partitioning inhibiting
the reduction process. The experimental results were used to develop a model for the
reduction process.
Koafmacher et al [137] employed a short clean-up of procedure followed by electron capture gas chromatography for the determination of octachlorodibenzo-p-dioxin
in soils using a furzed silica capillary gas chromatographic column. The technique was
suitable as a routine screening procedure for samples taken from contaminated sites.
Christman et al [138] gave details of procedures for extraction, clean-up, and
concentration of samples of soil prior to the determination of polychlorinated dibenzop-dioxins and polychlorinated dibenzofurans by gas chromatography and by gas
chromatography-mass spectrometry. Instrumental parameters are also included. Some
typical results are tabulated.
The benzene-water extraction gas chromatographic procedure described by Bride
et al [222] for the determination of aliphatic hydrocarbons in soil has also been applied
to the determination of polychlorinated dibenzo-p-dioxins in soil [140].
Otaka et al [140] have carried out a detailed study of the extractability of dioxins
from suspended sediments in water. These workers evaluated the extractability of dioxins from suspended substances in distributed water. Dioxins adsorbed on the collected
suspended solids were extracted by pressurised liquid extraction with various solvents.
High-poloarity solvents (acetone, alcohols) extracted considerably higher amounts of
some lower-chlorinated dibenzo-p-dioxins (LoCDD) than did low-polarity solvents
(dichloromethane, toluene), whereas the extracted amounts of higher-chlorinated
dibenzo-p-dioxins (HiCDDs) were roughly the same, regardless of the solvent. The
extractability of the LoCDDs depended on the isomer. Daily variations in quantities for
polychlorodibenzo dioxins organic matter and iron in the suspended soils were examined, and the results suggested that in the suspended solid, LoCDDs and HiCDDs were
associated, respectively, with raw water-derived organic matter and microparticles
sequestered in iron oxyl (hydr) oxide floc. It was also suggested that the low extractability of certain congeners was not attributable to the coexisting ferric compounds but
was probably attributable to organic matter with which they strongly associate.
Various other workers have discussed methodology for the determination of
µg kg
−1 levels of 176 polychlorodibenzo-p-dioxins and polychlorodibenzofurans in
sediments [46, 141–146] an silts [147]. The method described by Smith et al [46]
for the determination of polychlorodibenzo-p-dioxins and dibenzofurans in soils and
is also applicable to sediment. Taguchi [143] present preliminary results obtained in
a round robin inter-laboratory study on various techniques using gas chromatography and mass spectrometry for the determination of polychlorodibenzo-p-dioxins and
polychlorodibenzofurans in sediments. Clean-up techniques are discussed.
6.4 NITROGEN CONTAINING COMPOUNDS
Weber and Wolfe et al [147] have shown that aromatic diazocompounds in sediments
were readily degraded by an abiotic surface-mediated reaction. The exact nature of the
reducing agent was not determined, but it appeared to be associated with the sediment.
There was no apparent correlation between the rate of degradation and the measured
reduction potential of the diazo dyes. The rate of degradation appeared to be controlled
by the amount of partitioning on the sediment, with increasing partitioning inhibiting
the reduction process. The experimental results were used to develop a model for the
reduction process.