Abstract:
This study was carried out to determine the 96h LC50 value of two selected heavy
metals (copper and cadmium) in the spiked sediment towards 'blood worm' or
Chironomus sp. It was also to study the relationship between pore water metal content
and toxicity. The concentration of Cd-spiked sediment used in this sediment toxicity test
was l .95ppm, 33.85ppm, 63.80ppm, 99.05ppm and 186.20ppm. For Cu-spiked sediment,
the concentration used is 4.65ppm, 157ppm, 365ppm, 486ppm and 669ppm. Replicates
were conducted for each concentration of both metals. This study was done in duplicate
for each concentration of both metals. 96h LC50 values obtained for Cu-spiked sediment
was 194.142ppm, while for Cd-spiked sediment, the 96h LC50 values obtained was
85.541ppm. The toxicity effect was much higher in Cd compared to Cu. Pore water metal
content in Cd-spiked sediment was higher compared to sediment and water column Cd
concentration. The moving of metal from sediment to pore water as well as water column
represents the cyclic motion of metals trough absorption.
