The captain of the ship became aware last week that two 20-foot-long cargo containers were leaking a white powder used as an industrial disinfectant and bleaching agent, with a strong chlorine odor.
A port spokesman said the cause of the leak was loose-fitting packaging.
The APL shipping terminal was closed for 90 minutes as the containers were moved to another area and were emptied.
There were no reports of illnesses or injuries.