180
Crustacea and Molluscs
From the results in Table 8.3 for total vanadium contents, it is apparent that higher
vanadium contents were obtained in industrialized areas than in the nonindustrialized San Luis Pass area.
8.1.9
Zinc
It has been reported [546] that no loss of zinc occurs when mussels are dry ashed at
450-550 °c in porcelain crucibles and the zinc subsequently dissolved in hydrochloric
acid.
8.1.10
Multielements
Atomic Absorption Spectrometry. The nitric acid digestion-atomic absorption spectrometric procedure [385], described under multielement analysis in Sect. 7.1.10 for
the determination of cadmium, lead, copper, manganese, zinc, and chromium in fish,
has also been applied to the determination of these elements in shrimp, crab, oyster,
and mussels.
Four arbitrarily chosen sizes of Mediterranean Mussel, collected near Gemlik on the
Sea of Marmara in Western Turkey, were analyzed for mercury, cadmium, copper,
and lead. The analytical results, together with the weights and shell length, are given
in Table 8.4.
The ability of shellfish to concentrate many elements is well known. It is thus
expected that the mussel, which gets its nourishment by effectively flltering the
surrounding water, might show an increase in the concentration of some elements
with size (and thus age). Such a trend is indicated in Table 8.4 for cadmium and
copper, although more data is needed to be conclusive.
Topping [552] has reported on interlaboratory comparison studies on atomic
absorption spectrometric and other methods for the determination of lead and cadmium in crab and lobster. He demonstrated that the majority of the participants in
this study can produce comparable (i. e. inter-laboratory CV of 17 %) and accurate
data for cadmium at a tissue concentration of around 10 !J.ll101 kg-I, which is typically
encountered in shellfish monitoring programmes. Unfortunately, the results of the
analysis oflead indicate that difficulties are experienced in producing comparable and
Table 8.4 Trace metal concentrations of Mediterranean mussel vs size (from [385])
~g g-I (fresh weight)
Size
Total
Fresh
Shell
weight
weight
length
Hg
Cd
Cu
Pb
(g)
(g)
(cm)
Very small (I)
6.2
1.0
4.0
0.03
Very small (II)
7.2
1.7
4.4
0.75
0.48
Small (I)
ll.8
2.3
5.5
0.05
Small (II)
17.9
5.8
5.8
0.07
0.89
0.54
Medium
27.7
5.9
7.3
0.02
0.24
1.27
0.61
Large
67.8
7.4
8.7
0.05
0.40
2.65
0.57
Crustacea and Molluscs
From the results in Table 8.3 for total vanadium contents, it is apparent that higher
vanadium contents were obtained in industrialized areas than in the nonindustrialized San Luis Pass area.
8.1.9
Zinc
It has been reported [546] that no loss of zinc occurs when mussels are dry ashed at
450-550 °c in porcelain crucibles and the zinc subsequently dissolved in hydrochloric
acid.
8.1.10
Multielements
Atomic Absorption Spectrometry. The nitric acid digestion-atomic absorption spectrometric procedure [385], described under multielement analysis in Sect. 7.1.10 for
the determination of cadmium, lead, copper, manganese, zinc, and chromium in fish,
has also been applied to the determination of these elements in shrimp, crab, oyster,
and mussels.
Four arbitrarily chosen sizes of Mediterranean Mussel, collected near Gemlik on the
Sea of Marmara in Western Turkey, were analyzed for mercury, cadmium, copper,
and lead. The analytical results, together with the weights and shell length, are given
in Table 8.4.
The ability of shellfish to concentrate many elements is well known. It is thus
expected that the mussel, which gets its nourishment by effectively flltering the
surrounding water, might show an increase in the concentration of some elements
with size (and thus age). Such a trend is indicated in Table 8.4 for cadmium and
copper, although more data is needed to be conclusive.
Topping [552] has reported on interlaboratory comparison studies on atomic
absorption spectrometric and other methods for the determination of lead and cadmium in crab and lobster. He demonstrated that the majority of the participants in
this study can produce comparable (i. e. inter-laboratory CV of 17 %) and accurate
data for cadmium at a tissue concentration of around 10 !J.ll101 kg-I, which is typically
encountered in shellfish monitoring programmes. Unfortunately, the results of the
analysis oflead indicate that difficulties are experienced in producing comparable and
Table 8.4 Trace metal concentrations of Mediterranean mussel vs size (from [385])
~g g-I (fresh weight)
Size
Total
Fresh
Shell
weight
weight
length
Hg
Cd
Cu
Pb
(g)
(g)
(cm)
Very small (I)
6.2
1.0
4.0
0.03
Very small (II)
7.2
1.7
4.4
0.75
0.48
Small (I)
ll.8
2.3
5.5
0.05
Small (II)
17.9
5.8
5.8
0.07
0.89
0.54
Medium
27.7
5.9
7.3
0.02
0.24
1.27
0.61
Large
67.8
7.4
8.7
0.05
0.40
2.65
0.57