214
Phytoplankton
9.2.4
Mercury
The neutron activation analysis procedure [382], described under mercury in
Sect. 7.1.6 for the determination of mercury in fish, has been applied to the determination of mercury in algae. Some 50-60 % of mercury was lost from algae as volatile
organic mercury compounds upon attempting to dry algae samples by freeze drying,
or upon drying at 60°C prior to neutron activation analysis. To avoid these errors, wet
algae samples were centrifuged to remove excess moisture, and portions of this
material were put in polyethylene bags for neutron activation analysis and subjected
to weight loss determination at 60 °c to ascertain moisture content so that neutron
activation results could be calculated on a dry weight basis.
Mercury determinations on plankton algae, carried out on various dates between
1970 and 1971, on samples collected in lake Erie were in the range 31 to 81 mgkg-l.
Mitchell et al. [622] evaluated the use of electrothermal vaporization-direct-current
argon-plasma emission spectrometry for direct determination of mercury compounds in Chlorella vulgaris. Here, 5-ml volumes of20 Ilg ml- 1 mercury solution were
equilibrated with 0.6 to 9-mg algal masses. The amount of mercury taken up (60900 Ilg) was linearly related to algal mass. Acceptable calibration curves were obtained
for up to 20 mg of mercury absorbed into 5-mg algal masses. The effects of mercury(II) chloride, mercury(I) chloride and mercury(I1) acetate on the mercury emission
signal were examined. The addition of sulphur-containing algae or cysteine made the
mercury signal the same, regardless of the mercury compound originally present.
9.2.5
Tin
The atomic absorption spectrometric method [320], described under tin in Sect. 4.5.3
for the determination of tin in marine sediments, has been applied to the determination of tin in macroalgae samples. T in concentrations found in algae samples collected
from Narragansett Bay, California were in the range 0.03 mg kg- 1 (inner tissue of
algae) to 0.83 mg kg- 1 (algae blade). In these cases, the samples were destroyed by
acids, and it is assumed that all tin forms end up as Sn(IV) and that no losses occur
during the wet ashing procedure.
Dogan and Haerdi [623] also applied graphite furnace atomic absorption spectrometry to the determination of tin in algae. They digested the sample with Lumatom at
50°C, injected it into a graphite furnace, and ashed at 800°C for 40 s. The material
was then atomized at 2860 °c for 5 s before analysis for tin.
9.2.6
Multielements
Atomic Absorption Spectrometry. Bando et al. [625] studied analytical errors associated with trace element determination in algae by atomic absorption spectrometry. In
this method, algae was filtered from the water sample on 47 mm Nucleopane 0.4 J.1ffi
polycarbonate filters which were then weighed and dried overnight at 65°C. After
drying overnight at 65 °c, the filters were re-weighed and transferred into the PTFE
Phytoplankton
9.2.4
Mercury
The neutron activation analysis procedure [382], described under mercury in
Sect. 7.1.6 for the determination of mercury in fish, has been applied to the determination of mercury in algae. Some 50-60 % of mercury was lost from algae as volatile
organic mercury compounds upon attempting to dry algae samples by freeze drying,
or upon drying at 60°C prior to neutron activation analysis. To avoid these errors, wet
algae samples were centrifuged to remove excess moisture, and portions of this
material were put in polyethylene bags for neutron activation analysis and subjected
to weight loss determination at 60 °c to ascertain moisture content so that neutron
activation results could be calculated on a dry weight basis.
Mercury determinations on plankton algae, carried out on various dates between
1970 and 1971, on samples collected in lake Erie were in the range 31 to 81 mgkg-l.
Mitchell et al. [622] evaluated the use of electrothermal vaporization-direct-current
argon-plasma emission spectrometry for direct determination of mercury compounds in Chlorella vulgaris. Here, 5-ml volumes of20 Ilg ml- 1 mercury solution were
equilibrated with 0.6 to 9-mg algal masses. The amount of mercury taken up (60900 Ilg) was linearly related to algal mass. Acceptable calibration curves were obtained
for up to 20 mg of mercury absorbed into 5-mg algal masses. The effects of mercury(II) chloride, mercury(I) chloride and mercury(I1) acetate on the mercury emission
signal were examined. The addition of sulphur-containing algae or cysteine made the
mercury signal the same, regardless of the mercury compound originally present.
9.2.5
Tin
The atomic absorption spectrometric method [320], described under tin in Sect. 4.5.3
for the determination of tin in marine sediments, has been applied to the determination of tin in macroalgae samples. T in concentrations found in algae samples collected
from Narragansett Bay, California were in the range 0.03 mg kg- 1 (inner tissue of
algae) to 0.83 mg kg- 1 (algae blade). In these cases, the samples were destroyed by
acids, and it is assumed that all tin forms end up as Sn(IV) and that no losses occur
during the wet ashing procedure.
Dogan and Haerdi [623] also applied graphite furnace atomic absorption spectrometry to the determination of tin in algae. They digested the sample with Lumatom at
50°C, injected it into a graphite furnace, and ashed at 800°C for 40 s. The material
was then atomized at 2860 °c for 5 s before analysis for tin.
9.2.6
Multielements
Atomic Absorption Spectrometry. Bando et al. [625] studied analytical errors associated with trace element determination in algae by atomic absorption spectrometry. In
this method, algae was filtered from the water sample on 47 mm Nucleopane 0.4 J.1ffi
polycarbonate filters which were then weighed and dried overnight at 65°C. After
drying overnight at 65 °c, the filters were re-weighed and transferred into the PTFE