54
River and Stream Sediments
liquid-solid adsorbents are silicic acid. Standard gas chromatographic separations for
complex mixtures employ non-polar columns packed with OV-1, OV-17, OV-101,
SE-30 or glass capillary columns containing similar phases.
2.4.5
Humic and Fulvic Acids
Klenke et al. [103] described a technique for extraction of humic and fulvic acids from
stream sediments and outlined methods for their determination by means of flame
atomic absorption spectrometry, the levels of environmentally important heavy metals (cadmium, copper, chromium, cobalt, nickel and lead) in the fulvic and humic
acid extracts were compared with those in the original sediment samples. The pattern
distribution of the respective metals in the two cases showed very close agreement,
suggesting that the combined extract of humic and fulvic acids could be used as an
indicator of the level of heavy metal pollution in flowing waters.
2.4.6
Carbohydrates
Pellenberg [104] analysed river sediment for silicone content by nitrous oxideacetylene flame atomic absorption spectrophotometry. He showed that total carbon
and total carbohydrates both correlate well with silicone content and the correlation
between sedimentary silicone and presumed sewage material is good enough to
suggest silicone as a totally synthetic, specific tracer for sewage in the aquatic environment.
McQuaker and Fung [85] determined carbohydrates in sediments spectrophotometrically at 485 nm by reacting with phenol and concentrated sulphuric acid.
2.4.7
Phthalate Esters
Schwartz et al. [105] have described a high performance liquid chromatographic
method for determining di-2-ethylhexyl and di-n-butyl phthalate in river sediments.
This method requires no sample clean-up and consists of a single extraction step
followed by quantitative analysis using high performance liquid chromatography.
Following the procedure described above, it is possible to detect down to 10 ng of
both esters, i. e. equivalent to 0.5 mg kg-I.
Figure 2.8 shows a typical chromatogram of a hexane extract of sediment taken from
the river Rhine.
Thuren [106] determined phthalates in sediment using solvent extraction (acetonitrile, petroleum ether), clean-up with deactivated Florisil, and quantitative analysis by
gas chromatography. The detector response was linear between 0.5 and 100 ng. The
detection limit (signal:noise ratio 2:1) was 0.1 ng for dimethylphthalate, dibutylphthalate and di(2-ethylhexyl}phthalate, and 0.05 ng for benzoylbutylphthalate. Recovery
was between 30 % and 130 % depending on the ester. Low recovery for dimethylphthalate (30 %) was probably due to pyrolysis in the detector (detector temperature
was 320°C).
River and Stream Sediments
liquid-solid adsorbents are silicic acid. Standard gas chromatographic separations for
complex mixtures employ non-polar columns packed with OV-1, OV-17, OV-101,
SE-30 or glass capillary columns containing similar phases.
2.4.5
Humic and Fulvic Acids
Klenke et al. [103] described a technique for extraction of humic and fulvic acids from
stream sediments and outlined methods for their determination by means of flame
atomic absorption spectrometry, the levels of environmentally important heavy metals (cadmium, copper, chromium, cobalt, nickel and lead) in the fulvic and humic
acid extracts were compared with those in the original sediment samples. The pattern
distribution of the respective metals in the two cases showed very close agreement,
suggesting that the combined extract of humic and fulvic acids could be used as an
indicator of the level of heavy metal pollution in flowing waters.
2.4.6
Carbohydrates
Pellenberg [104] analysed river sediment for silicone content by nitrous oxideacetylene flame atomic absorption spectrophotometry. He showed that total carbon
and total carbohydrates both correlate well with silicone content and the correlation
between sedimentary silicone and presumed sewage material is good enough to
suggest silicone as a totally synthetic, specific tracer for sewage in the aquatic environment.
McQuaker and Fung [85] determined carbohydrates in sediments spectrophotometrically at 485 nm by reacting with phenol and concentrated sulphuric acid.
2.4.7
Phthalate Esters
Schwartz et al. [105] have described a high performance liquid chromatographic
method for determining di-2-ethylhexyl and di-n-butyl phthalate in river sediments.
This method requires no sample clean-up and consists of a single extraction step
followed by quantitative analysis using high performance liquid chromatography.
Following the procedure described above, it is possible to detect down to 10 ng of
both esters, i. e. equivalent to 0.5 mg kg-I.
Figure 2.8 shows a typical chromatogram of a hexane extract of sediment taken from
the river Rhine.
Thuren [106] determined phthalates in sediment using solvent extraction (acetonitrile, petroleum ether), clean-up with deactivated Florisil, and quantitative analysis by
gas chromatography. The detector response was linear between 0.5 and 100 ng. The
detection limit (signal:noise ratio 2:1) was 0.1 ng for dimethylphthalate, dibutylphthalate and di(2-ethylhexyl}phthalate, and 0.05 ng for benzoylbutylphthalate. Recovery
was between 30 % and 130 % depending on the ester. Low recovery for dimethylphthalate (30 %) was probably due to pyrolysis in the detector (detector temperature
was 320°C).