68
Lake and Pond Sediments
Jirka and Charter [195] have applied an automated method to the determination of
mercury in lake sediments. Aqueous suspensions of sediment samples are automatically analyzed using the cold-vapour detection method following a persulfate oxidation and stannous chloride reduction. The method completely recovers mercuric
sulfide. Samples are analyzed at the rate of 30 h, with a routine detection limit of
0.1 mg Hg kg- I of sample, and an average relative deviation of 5 % at the level of
20-30 mg kg-I.
Mudrock and Kokitich [196] determined mercury in lake sediments from the St
Clair Lake using a gold film mercury analyser. The mercury was extracted from the
sediment by extraction with a mixture of nitric and hydrochloric acids (9:1 v Iv). An
accuracy of 0.02 mg kg- I was achieved.
3.1.3
Silver
The determination of various forms of silver in sediments is discussed in Sect. 2.1.10.
Table 3.2 presents the results obtained in the determination of various species of silver
taken from a sediment core sample from Moira Lake, Ontario.
3.1.4
Selenium
A fluorescence spectroscopic method has been applied to the determination of selenium in lake sediments [197].
3.1.5
Tin
Dogan and Haerdi [198] applied their flameless atomic absorption method to the
determination of down to 0.5 f.1g kg- I tin in humus rich lake sediments. Sample
digestion was carried out using Lumatom, a quarternary ammonium hydroxide,
dissolved in isopropanol (available from H Kurner D-63543 Neuberg, Germany).
Table 3.2
Distribution of the chemical forms of silver in a sediment core (from [7])
Total
Fe,Mn
Organic
concenExchangeable Carbonate
oxide
sulphide Residual
tration
forms
surface oxide
bound
bound
forms
Sediment depth cm Ilg g-I
Ilg g-I
bound I1gg- 1
Ilg g-I
Ilg g-I
I1gg- 1
0-1
.. 5.53
0.52
0.03
0.03
2.31
2.70
9-10
.. 8.05
0.63
0.03
0.03
2.02
5.40
14-15
.. 6.60
0.90
0.03
0.03
1.30
4.40
18-19
.. 3.66
0.12
0.03
0.03
0.24
3.30
21-22
.. 4.30
0.10
0.03
0.03
0.36
3.84
32-33
.. 1.00
0.03
0.03
0.03
0.16
0.84
Lake and Pond Sediments
Jirka and Charter [195] have applied an automated method to the determination of
mercury in lake sediments. Aqueous suspensions of sediment samples are automatically analyzed using the cold-vapour detection method following a persulfate oxidation and stannous chloride reduction. The method completely recovers mercuric
sulfide. Samples are analyzed at the rate of 30 h, with a routine detection limit of
0.1 mg Hg kg- I of sample, and an average relative deviation of 5 % at the level of
20-30 mg kg-I.
Mudrock and Kokitich [196] determined mercury in lake sediments from the St
Clair Lake using a gold film mercury analyser. The mercury was extracted from the
sediment by extraction with a mixture of nitric and hydrochloric acids (9:1 v Iv). An
accuracy of 0.02 mg kg- I was achieved.
3.1.3
Silver
The determination of various forms of silver in sediments is discussed in Sect. 2.1.10.
Table 3.2 presents the results obtained in the determination of various species of silver
taken from a sediment core sample from Moira Lake, Ontario.
3.1.4
Selenium
A fluorescence spectroscopic method has been applied to the determination of selenium in lake sediments [197].
3.1.5
Tin
Dogan and Haerdi [198] applied their flameless atomic absorption method to the
determination of down to 0.5 f.1g kg- I tin in humus rich lake sediments. Sample
digestion was carried out using Lumatom, a quarternary ammonium hydroxide,
dissolved in isopropanol (available from H Kurner D-63543 Neuberg, Germany).
Table 3.2
Distribution of the chemical forms of silver in a sediment core (from [7])
Total
Fe,Mn
Organic
concenExchangeable Carbonate
oxide
sulphide Residual
tration
forms
surface oxide
bound
bound
forms
Sediment depth cm Ilg g-I
Ilg g-I
bound I1gg- 1
Ilg g-I
Ilg g-I
I1gg- 1
0-1
.. 5.53
0.52
0.03
0.03
2.31
2.70
9-10
.. 8.05
0.63
0.03
0.03
2.02
5.40
14-15
.. 6.60
0.90
0.03
0.03
1.30
4.40
18-19
.. 3.66
0.12
0.03
0.03
0.24
3.30
21-22
.. 4.30
0.10
0.03
0.03
0.36
3.84
32-33
.. 1.00
0.03
0.03
0.03
0.16
0.84