88
Marine Sediments
high adsorption capacity, and permits the fractionated desorption of accumulated
material.
Hayase et al. [729] applied reversed phase liquid chromatography with double detectors (fluorescence and absorption) to the determination of dissolved organic matter in
estuarine sea water. The dissolved organic matter was extracted into chloroform at
pH 3 or 8. The hydrophilic-hydrophobic balance and aromatic character of the sea
water dissolved organic matter was represented on the chromatograms. The results
indicated that reversed phase liquid chromatography with double detectors was an
effective technique in the characterization of dissolved organic matter in sea water.
4.1.5
Fractionation by Chemical Leaching
Different chemical reagents dissolve different proportions of a sediment sample and
the concentration of inorganic or organic substances will differ in each fraction. Thus
the following reagents dissolve the different percentages of a sediment and the stated
percentage of the total cadmium content of the unfractionated samples is found in
each fraction.
Extractant
LiCl-CsCI MeOH @ 20 ·C
CH 3 COONa, pH 5.0 @ 20 ·C
Species extracted
readily exchanged ions
carbonate bound surface
Cadmium. % of total cadmium content of unfractionated sample found in
the fraction
17
oxide bound ions
31
NH 2 0H.HCl-CH 3 COOH @ 20·C ions bound to Fe and Mn oxides
34
H 2 0 2 , pH 2.0 @ 90 ·C
aqua regia-HF-HCl-H 2 0 2
4.1.6
Fractionation by Sedimentation
organically and sulphide
bound ions
ions bound to residual phase
12
6
A dispersion of dry sediment in sea water can be used to carry out sedimentation
measurements of the particle size distribution of sediments [708]. In this procedure
the sediment to be analysed is introduced as a 5 % suspension in water into the
sedimentation cell by means of a peristaltic pump. A finely collimated beam of Xrays
is passed through the suspended medium. Radiation is detected as pulses by a
scintillation detector on the opposing side of the cell to the source. The con<;entration
of sediment in the beam is proportional to the Xray intensity. The sedimentation cell
is continuously moved across the beam to reduce the analysis time. A computer solves
Stokes Law and presents the result linearly as a cumulative mass per cent distribution.
Fig. 4.3 depicts curves drawn for results obtained on a silt sample.
Cumulative per cent distribution curves obtained by the sedigraph and three other
methods are compared in Fig. 4.4. It is clear that »different" results are obtained using
Marine Sediments
high adsorption capacity, and permits the fractionated desorption of accumulated
material.
Hayase et al. [729] applied reversed phase liquid chromatography with double detectors (fluorescence and absorption) to the determination of dissolved organic matter in
estuarine sea water. The dissolved organic matter was extracted into chloroform at
pH 3 or 8. The hydrophilic-hydrophobic balance and aromatic character of the sea
water dissolved organic matter was represented on the chromatograms. The results
indicated that reversed phase liquid chromatography with double detectors was an
effective technique in the characterization of dissolved organic matter in sea water.
4.1.5
Fractionation by Chemical Leaching
Different chemical reagents dissolve different proportions of a sediment sample and
the concentration of inorganic or organic substances will differ in each fraction. Thus
the following reagents dissolve the different percentages of a sediment and the stated
percentage of the total cadmium content of the unfractionated samples is found in
each fraction.
Extractant
LiCl-CsCI MeOH @ 20 ·C
CH 3 COONa, pH 5.0 @ 20 ·C
Species extracted
readily exchanged ions
carbonate bound surface
Cadmium. % of total cadmium content of unfractionated sample found in
the fraction
17
oxide bound ions
31
NH 2 0H.HCl-CH 3 COOH @ 20·C ions bound to Fe and Mn oxides
34
H 2 0 2 , pH 2.0 @ 90 ·C
aqua regia-HF-HCl-H 2 0 2
4.1.6
Fractionation by Sedimentation
organically and sulphide
bound ions
ions bound to residual phase
12
6
A dispersion of dry sediment in sea water can be used to carry out sedimentation
measurements of the particle size distribution of sediments [708]. In this procedure
the sediment to be analysed is introduced as a 5 % suspension in water into the
sedimentation cell by means of a peristaltic pump. A finely collimated beam of Xrays
is passed through the suspended medium. Radiation is detected as pulses by a
scintillation detector on the opposing side of the cell to the source. The con<;entration
of sediment in the beam is proportional to the Xray intensity. The sedimentation cell
is continuously moved across the beam to reduce the analysis time. A computer solves
Stokes Law and presents the result linearly as a cumulative mass per cent distribution.
Fig. 4.3 depicts curves drawn for results obtained on a silt sample.
Cumulative per cent distribution curves obtained by the sedigraph and three other
methods are compared in Fig. 4.4. It is clear that »different" results are obtained using