| Summary: | 碩士 === 國立海洋大學 === 水產養殖學系 === 84 === Abstract
The experiment was to simulate the effects of acid rain
on the accumulation of heavy metals in muscle of tilapia
(Oreochromis niloticus, L). Tilapia averaged 10.5 g were
reared for 8 weeks in water containing 4 metals with 3
concentrations (Cu: 3.5, 7.0 and 14.0 ppm; Cd: 0.4, 0.8 and
1.6 ppm; Pb: 7.0, 14.0 and 28.0 ppm; Zn: 13.0, 26.0 and 52.0
ppm) under 2 pH conditions (5.0 and 7.0). Each treatment
combination had 2 replicates. Control group ( pH = 7, no
metals added) had 4 replicates. Metals concentration in
muscle was analyzed every 2 weeks.
The results showed that Cu concentration in muscle of fish
reared under pH 7.0 (8.91 ppm) was significantly(p ≦ 0.05)
higher then that under pH 5.0 group(5.46 ppm). It may be
attributed to the increase of Cu precipitation under high pH
and the reaction towards the formation of copper sulfate which
was easier absorbed by fish. Cu concentration in muscle
increasd as Cu in water increased. Up to 6 weeks, Cu
concentration in muscle increased with elapsed time.
However, Cu concentration in muscle decreased from 6 to 8
weeks.
Cd concentration in muscle of fish reared under pH 5.0 (0.41
ppm) was not significantly (p ＞ 0.05) different from that
under pH 7.0 (0.39 ppm). Cd concentration in muscle
increased as Cd in water increased. Cd concentration in
muscle increased with elapsed time until 6 weeks and then
decreased.
Pb concentration in muscle of fish reared under pH 5.0
(1.98 ppm) environment was significantly higher then that under
pH 7.0 (0.57 ppm). The higher Pb concentration in water, the
higher Pb concentration in muscle. Pb concentration in muscle
increased with elapsed time. Pb concentration in muscle of
fish at 8 weeks was found significantly higher than that at
4 weeks, but there was no significant differences in Pb
concentration in muscle of fish for 2, 4 and 6 weeks.
Zn concentration in muscle of fish reared under pH 5.0 (131.49
ppm) was not significantly different from that under pH
7.0 (147.71 ppm). Zn concentration in muscle increased with
increasing Zn concentration in water and elapsed time.
There was no significantly difference in growth of fish among
various pH and concentration of metals.
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