Abstract:
This study was carried out to determine the LC5o value of zinc and to investigate how
the substrate can affect the LC50 value on the zinc toxicity towards Chironomus sp.
The Chironomus larvae were exposed to 5 different concentration of zinc (20, 40, 60,
80, 100 ppm) and control for 96 hours in three different aquatic media - without
substrate, with silica, with sediment. It was found that the median LC5o of zinc was
30.7 mg/L in the aquatic medium without substrate, 52.2 mg/Lin the aquatic medium
with silica, and 34. 7 mg/L in the aquatic medium with sediment. The experiments on
the different substrate indicated that silica resulted in a significant reduction of zinc
toxicity to the Chironomus larvae while the LC50 value of zinc in the tests with
sediment was similar to the tests in water only.
