94
Marine Sediments
4.2.77
Selenium
Siu and Berman [269] determined down to 0.2 pg selenium in marine sediments by a
procedure involving acid digestion in a PTFE bomb, conversion to 5-nitropiazselenol,
and electron capture gas chromatography of the toluene extract.
Willie et al. [270] have described a method for the determination of down to 1.4 J.1g
kg-I total selenium in marine sediments based on the generation of SeH2 using sodium
borohydride with its subsequent trapping in graphite furnace at 600°C. Typical
precisions of 5-10 % are claimed for this method. Copper, nickel, iron, and arsenic
did not interfere at the concentrations likely to occur in sediments. Using this method, a selenium content of 2.13 ± 0.10 mg kg-I was obtained on reference marine
sediment NBS 1566 compared to an accepted value of 2.1 ± 0.5 mg kg-I.
4.2.72
Silver
Bloom [268] has used Zeeman corrected graphite furnace atomic absorption spectrometry to determine silver in marine sediments.
4.2.73
Thallium
Riley and Siddique [271] described procedure for the determination of thallium in
deep sea sediments. It involves preliminary concentration by adsorption on a strongly
basic anion-exchange resin as the tetrachlorothallate ion, followed by elution with
sulphur dioxide, and evaporation, before determination by graphite furnace atomic
absorption spectrometry or differential pulse anodic stripping voltammetry. There
was good agreement between the results obtained by the two methods.
4.2.74
Zirconium
Sastry et al. [272] separated zirconium from marine sediments by digestion with
hydrochloric acid, then coprecipitated zirconium with cerium iodide prior to spectrophotometric determination as the Alizarin R-Mordant Red-S chromophore.
4.2.75
Multielements
Atomic Absorption Spectrometry. Pilkington and Warren [273] have described a
method for studying the distribution of heavy metals (lead, cadmium, and zinc) in
marine sediments in which the various sediment components, including organic
matter, are separated into distinct bands by centrifuging in tetrabromoethane. Total
elements are then determined using direct flame and graphite furnace atomic absorption spectrometry. Table 4.4 shows the mineral components of the density subfractions and the heavy metal contents of these. It may be seen from Table 4.4 that the
mass balances obtained for lead and cadmium were satisfactory, but that there was
Marine Sediments
4.2.77
Selenium
Siu and Berman [269] determined down to 0.2 pg selenium in marine sediments by a
procedure involving acid digestion in a PTFE bomb, conversion to 5-nitropiazselenol,
and electron capture gas chromatography of the toluene extract.
Willie et al. [270] have described a method for the determination of down to 1.4 J.1g
kg-I total selenium in marine sediments based on the generation of SeH2 using sodium
borohydride with its subsequent trapping in graphite furnace at 600°C. Typical
precisions of 5-10 % are claimed for this method. Copper, nickel, iron, and arsenic
did not interfere at the concentrations likely to occur in sediments. Using this method, a selenium content of 2.13 ± 0.10 mg kg-I was obtained on reference marine
sediment NBS 1566 compared to an accepted value of 2.1 ± 0.5 mg kg-I.
4.2.72
Silver
Bloom [268] has used Zeeman corrected graphite furnace atomic absorption spectrometry to determine silver in marine sediments.
4.2.73
Thallium
Riley and Siddique [271] described procedure for the determination of thallium in
deep sea sediments. It involves preliminary concentration by adsorption on a strongly
basic anion-exchange resin as the tetrachlorothallate ion, followed by elution with
sulphur dioxide, and evaporation, before determination by graphite furnace atomic
absorption spectrometry or differential pulse anodic stripping voltammetry. There
was good agreement between the results obtained by the two methods.
4.2.74
Zirconium
Sastry et al. [272] separated zirconium from marine sediments by digestion with
hydrochloric acid, then coprecipitated zirconium with cerium iodide prior to spectrophotometric determination as the Alizarin R-Mordant Red-S chromophore.
4.2.75
Multielements
Atomic Absorption Spectrometry. Pilkington and Warren [273] have described a
method for studying the distribution of heavy metals (lead, cadmium, and zinc) in
marine sediments in which the various sediment components, including organic
matter, are separated into distinct bands by centrifuging in tetrabromoethane. Total
elements are then determined using direct flame and graphite furnace atomic absorption spectrometry. Table 4.4 shows the mineral components of the density subfractions and the heavy metal contents of these. It may be seen from Table 4.4 that the
mass balances obtained for lead and cadmium were satisfactory, but that there was