How Dangerous Is It: The Effect of Heavy Metals on Aquatic Life
Ashley (Yi-Chen) Lin
University Transition Program
Floor Location : S 175 V
It is common knowledge that heavy metals in marine environments can influence aquatic life. But how serious is this pollution? Are we exaggerating the effects of water pollution, or are we understating the dangers?
This project investigated the effect of common industrial heavy metals on the survival of aquatic life, and tested the concentrations where the populations began to become affected by the chemicals. The test organisms utilized for this experiment were daphnia, and the two heavy metals tested in the experiment were copper and zinc, which were tested as compounds: copper nitrate and zinc nitrate.
Approximately twenty daphnia were kept in each Erlenmeyer flask, which was filled with a solution that had been mixed using solid forms of each compound and diluted to different concentrations beforehand. Although the acute toxicity of the compounds on daphnia were researched prior to the start of the experiment, it took several trials to find a good range of concentrations. After several weeks of testing, with each trial lasting one week, it was concluded that daphnia populations severely declined in a 0.0275ppm solution of dissolved Cu(NO3)2 and completely deceased at a concentration of 0.055ppm. The populations in Zn(NO3)2 declined to only several daphnia left at 0.08125ppm, and perished at 0.1625ppm. On the other hand, several of the control groups were able to triple in population by the end of the week, showing that the daphnia in a test solution were critically affected.
It was shown in this investigation that the toxicity of both copper and zinc for daphnia were substantially greater than previously expected, and the LC50 values for daphnia in copper and zinc were extremely low.